Bug 575763: [WaLTable] Refactor (part 1)

  - Extract core module
  - Remove deprecated and duplicate code
  - Make LayerEvents immutable
  - Replace Column/Row events by Dim event implementations
  - Add nullable annotations
  - Add support for configuration of grid line color via registry

Change-Id: Ic3d8a8db8a0719c28caf988e0892ab40dda71649

458 files changed, 8142 insertions, 9107 deletions

diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/.classpath b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/.classpath
index b9bb8eaa..4f143da2 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/.classpath
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/.classpath
@@ -12,5 +12,7 @@
 		</attributes>
 	</classpathentry>
 	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="src" path="srcBase"/>
+	<classpathentry kind="src" path="srcAdditional"/>
 	<classpathentry kind="output" path="target/classes"/>
 </classpath>
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/META-INF/MANIFEST.MF b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/META-INF/MANIFEST.MF
index 38bdbbb0..2f8c0176 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/META-INF/MANIFEST.MF
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/META-INF/MANIFEST.MF
@@ -11,16 +11,28 @@ Bundle-RequiredExecutionEnvironment: JavaSE-11
 Require-Bundle: org.eclipse.core.runtime;bundle-version="3.16.0",
  org.eclipse.swt,
  org.eclipse.jface
-Import-Package: org.eclipse.statet.jcommons.lang;version="4.5.0"
+Import-Package: org.eclipse.statet.jcommons.collections;version="4.5.0",
+ org.eclipse.statet.jcommons.lang;version="4.5.0"
 Export-Package: org.eclipse.statet.ecommons.waltable,
  org.eclipse.statet.ecommons.waltable.command,
  org.eclipse.statet.ecommons.waltable.config,
  org.eclipse.statet.ecommons.waltable.conflation,
  org.eclipse.statet.ecommons.waltable.coordinate,
  org.eclipse.statet.ecommons.waltable.copy,
- org.eclipse.statet.ecommons.waltable.copy.action,
- org.eclipse.statet.ecommons.waltable.data,
+ org.eclipse.statet.ecommons.waltable.copy.ui.action,
+ org.eclipse.statet.ecommons.waltable.core,
+ org.eclipse.statet.ecommons.waltable.core.command,
+ org.eclipse.statet.ecommons.waltable.core.config,
+ org.eclipse.statet.ecommons.waltable.core.coordinate,
+ org.eclipse.statet.ecommons.waltable.core.data,
+ org.eclipse.statet.ecommons.waltable.core.layer,
+ org.eclipse.statet.ecommons.waltable.core.layer.events,
+ org.eclipse.statet.ecommons.waltable.core.layer.top,
+ org.eclipse.statet.ecommons.waltable.core.style,
+ org.eclipse.statet.ecommons.waltable.core.swt,
+ org.eclipse.statet.ecommons.waltable.core.swt.painters,
  org.eclipse.statet.ecommons.waltable.data.convert,
+ org.eclipse.statet.ecommons.waltable.data.core,
  org.eclipse.statet.ecommons.waltable.data.validate,
  org.eclipse.statet.ecommons.waltable.edit,
  org.eclipse.statet.ecommons.waltable.edit.action,
@@ -28,47 +40,47 @@ Export-Package: org.eclipse.statet.ecommons.waltable,
  org.eclipse.statet.ecommons.waltable.edit.editor,
  org.eclipse.statet.ecommons.waltable.edit.gui,
  org.eclipse.statet.ecommons.waltable.export,
- org.eclipse.statet.ecommons.waltable.export.action,
  org.eclipse.statet.ecommons.waltable.export.config,
  org.eclipse.statet.ecommons.waltable.export.excel,
+ org.eclipse.statet.ecommons.waltable.export.ui.action,
  org.eclipse.statet.ecommons.waltable.freeze,
- org.eclipse.statet.ecommons.waltable.freeze.action,
- org.eclipse.statet.ecommons.waltable.freeze.config,
+ org.eclipse.statet.ecommons.waltable.freeze.core,
+ org.eclipse.statet.ecommons.waltable.freeze.swt,
+ org.eclipse.statet.ecommons.waltable.freeze.ui.action,
  org.eclipse.statet.ecommons.waltable.grid,
- org.eclipse.statet.ecommons.waltable.grid.cell,
- org.eclipse.statet.ecommons.waltable.grid.data,
- org.eclipse.statet.ecommons.waltable.grid.labeled,
- org.eclipse.statet.ecommons.waltable.grid.layer,
- org.eclipse.statet.ecommons.waltable.grid.layer.config,
- org.eclipse.statet.ecommons.waltable.layer,
+ org.eclipse.statet.ecommons.waltable.grid.config,
+ org.eclipse.statet.ecommons.waltable.grid.core,
+ org.eclipse.statet.ecommons.waltable.grid.core.data,
+ org.eclipse.statet.ecommons.waltable.grid.core.labeled,
+ org.eclipse.statet.ecommons.waltable.grid.core.layers,
+ org.eclipse.statet.ecommons.waltable.grid.swt,
  org.eclipse.statet.ecommons.waltable.layer.cell,
  org.eclipse.statet.ecommons.waltable.layer.config,
- org.eclipse.statet.ecommons.waltable.layer.event,
- org.eclipse.statet.ecommons.waltable.painter,
  org.eclipse.statet.ecommons.waltable.painter.cell,
  org.eclipse.statet.ecommons.waltable.painter.cell.decorator,
- org.eclipse.statet.ecommons.waltable.painter.layer,
  org.eclipse.statet.ecommons.waltable.persistence,
  org.eclipse.statet.ecommons.waltable.persistence.gui,
  org.eclipse.statet.ecommons.waltable.print,
- org.eclipse.statet.ecommons.waltable.print.action,
  org.eclipse.statet.ecommons.waltable.print.config,
+ org.eclipse.statet.ecommons.waltable.print.ui.action,
+ org.eclipse.statet.ecommons.waltable.refresh.core,
  org.eclipse.statet.ecommons.waltable.resize,
- org.eclipse.statet.ecommons.waltable.resize.action,
- org.eclipse.statet.ecommons.waltable.resize.config,
- org.eclipse.statet.ecommons.waltable.selection,
- org.eclipse.statet.ecommons.waltable.selection.action,
+ org.eclipse.statet.ecommons.waltable.resize.core,
+ org.eclipse.statet.ecommons.waltable.resize.ui.action,
  org.eclipse.statet.ecommons.waltable.selection.config,
+ org.eclipse.statet.ecommons.waltable.selection.core,
+ org.eclipse.statet.ecommons.waltable.selection.swt,
+ org.eclipse.statet.ecommons.waltable.selection.ui.action,
  org.eclipse.statet.ecommons.waltable.sort,
- org.eclipse.statet.ecommons.waltable.sort.action,
  org.eclipse.statet.ecommons.waltable.sort.config,
- org.eclipse.statet.ecommons.waltable.sort.painter,
+ org.eclipse.statet.ecommons.waltable.sort.core,
+ org.eclipse.statet.ecommons.waltable.sort.swt,
+ org.eclipse.statet.ecommons.waltable.sort.ui.action,
  org.eclipse.statet.ecommons.waltable.style,
  org.eclipse.statet.ecommons.waltable.style.editor,
- org.eclipse.statet.ecommons.waltable.swt,
  org.eclipse.statet.ecommons.waltable.tickupdate,
- org.eclipse.statet.ecommons.waltable.tickupdate.action,
  org.eclipse.statet.ecommons.waltable.tickupdate.config,
+ org.eclipse.statet.ecommons.waltable.tickupdate.ui.action,
  org.eclipse.statet.ecommons.waltable.tooltip,
  org.eclipse.statet.ecommons.waltable.ui,
  org.eclipse.statet.ecommons.waltable.ui.action,
@@ -76,8 +88,10 @@ Export-Package: org.eclipse.statet.ecommons.waltable,
  org.eclipse.statet.ecommons.waltable.ui.matcher,
  org.eclipse.statet.ecommons.waltable.ui.menu,
  org.eclipse.statet.ecommons.waltable.ui.mode,
+ org.eclipse.statet.ecommons.waltable.ui.swt.widgets,
  org.eclipse.statet.ecommons.waltable.ui.util,
  org.eclipse.statet.ecommons.waltable.util,
- org.eclipse.statet.ecommons.waltable.viewport,
- org.eclipse.statet.ecommons.waltable.viewport.action,
- org.eclipse.statet.ecommons.waltable.widget
+ org.eclipse.statet.ecommons.waltable.util.data,
+ org.eclipse.statet.ecommons.waltable.viewport.core,
+ org.eclipse.statet.ecommons.waltable.viewport.swt,
+ org.eclipse.statet.ecommons.waltable.viewport.ui.action
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/build.properties b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/build.properties
index a891cad1..8066e2cf 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/build.properties
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/build.properties
@@ -1,4 +1,6 @@
-source..= src/
+source..= src/,\
+          srcBase/,\
+          srcAdditional/
 output..= target/classes/
 bin.includes= META-INF/,\
               .,\
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/NatTable.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/NatTable.java
index da2a79b6..1d9e7ccb 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/NatTable.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/NatTable.java
@@ -13,15 +13,14 @@
 
 package org.eclipse.statet.ecommons.waltable;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
 
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.LinkedList;
 import java.util.List;
-import java.util.Properties;
+import java.util.Map;
 
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
@@ -45,59 +44,61 @@ import org.eclipse.swt.widgets.Event;
 import org.eclipse.swt.widgets.Listener;
 import org.eclipse.swt.widgets.ScrollBar;
 
+import org.eclipse.statet.jcommons.collections.CopyOnWriteIdentityListSet;
+import org.eclipse.statet.jcommons.collections.ImList;
+
 import org.eclipse.statet.ecommons.waltable.command.DisposeResourcesCommand;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.command.StructuralRefreshCommand;
-import org.eclipse.statet.ecommons.waltable.config.ConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.config.DefaultNatTableStyleConfiguration;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.config.IConfiguration;
 import org.eclipse.statet.ecommons.waltable.conflation.EventConflaterChain;
 import org.eclipse.statet.ecommons.waltable.conflation.IEventConflater;
 import org.eclipse.statet.ecommons.waltable.conflation.VisualChangeEventConflater;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.coordinate.PixelOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PixelOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.layer.ClientAreaProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerListener;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.VisualChangeEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.top.OverlayPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.top.TopLayer;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
+import org.eclipse.statet.ecommons.waltable.core.swt.painters.TableLayerPainter;
 import org.eclipse.statet.ecommons.waltable.edit.ActiveCellEditorRegistry;
-import org.eclipse.statet.ecommons.waltable.grid.ClientAreaResizeCommand;
-import org.eclipse.statet.ecommons.waltable.grid.InitializeGridCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerListener;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
-import org.eclipse.statet.ecommons.waltable.layer.event.IVisualChangeEvent;
-import org.eclipse.statet.ecommons.waltable.painter.IOverlayPainter;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-import org.eclipse.statet.ecommons.waltable.painter.layer.NatLayerPainter;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
-import org.eclipse.statet.ecommons.waltable.selection.CellSelectionEvent;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
-import org.eclipse.statet.ecommons.waltable.ui.IClientAreaProvider;
+import org.eclipse.statet.ecommons.waltable.grid.core.ClientAreaResizeCommand;
+import org.eclipse.statet.ecommons.waltable.refresh.core.StructuralRefreshCommand;
+import org.eclipse.statet.ecommons.waltable.selection.core.CellSelectionEvent;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.mode.ConfigurableModeEventHandler;
 import org.eclipse.statet.ecommons.waltable.ui.mode.Mode;
 import org.eclipse.statet.ecommons.waltable.ui.mode.ModeSupport;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
-import org.eclipse.statet.ecommons.waltable.viewport.RecalculateScrollBarsCommand;
-import org.eclipse.statet.internal.ecommons.waltable.LayerListenerList;
+import org.eclipse.statet.ecommons.waltable.viewport.core.RecalculateScrollBarsCommand;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
-public class NatTable extends Canvas implements ILayer, PaintListener, ILayerListener, IPersistable {
+public class NatTable extends Canvas implements TopLayer, PaintListener, LayerListener, Persistable {
 	
 	public static final int DEFAULT_STYLE_OPTIONS= SWT.NO_BACKGROUND | SWT.NO_REDRAW_RESIZE | SWT.DOUBLE_BUFFERED  | SWT.V_SCROLL | SWT.H_SCROLL;
 	
 	
-	private final NatTableDim hDim;
-	private final NatTableDim vDim;
+	private final NatTableLayerDim hDim;
+	private final NatTableLayerDim vDim;
 	
-	private IClientAreaProvider clientAreaProvider= new IClientAreaProvider() {
+	private ClientAreaProvider clientAreaProvider= new ClientAreaProvider() {
 		@Override
 		public LRectangle getClientArea() {
 			if (!isDisposed()) {
-				return SWTUtil.toNatTable(NatTable.this.getClientArea());
+				return SwtUtils.toNatTable(NatTable.this.getClientArea());
 			} else {
 				return new LRectangle(0, 0, 0, 0);
 			}
@@ -112,40 +113,40 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 	
 	private final EventConflaterChain conflaterChain= new EventConflaterChain();
 	
-	private final List<IOverlayPainter> overlayPainters= new ArrayList<>();
+	private final CopyOnWriteIdentityListSet<OverlayPainter> overlayPainters= new CopyOnWriteIdentityListSet<>();
 	
-	private final List<IPersistable> persistables= new LinkedList<>();
+	private final List<Persistable> persistables= new LinkedList<>();
 	
-	private ILayer underlyingLayer;
+	private Layer underlyingLayer;
 	
-	private IConfigRegistry configRegistry;
+	private ConfigRegistry configRegistry;
 	
 	protected final Collection<IConfiguration> configurations= new LinkedList<>();
 	
 	protected String id= GUIHelper.getSequenceNumber();
 	
-	private ILayerPainter layerPainter= new NatLayerPainter(this);
+	private LayerPainter layerPainter= new TableLayerPainter(this);
 	
 	private final boolean autoconfigure;
 	
 	
-	public NatTable(final Composite parent, final ILayer layer) {
+	public NatTable(final Composite parent, final Layer layer) {
 		this(parent, DEFAULT_STYLE_OPTIONS, layer);
 	}
 	
-	public NatTable(final Composite parent, final ILayer layer, final boolean autoconfigure) {
+	public NatTable(final Composite parent, final Layer layer, final boolean autoconfigure) {
 		this(parent, DEFAULT_STYLE_OPTIONS, layer, autoconfigure);
 	}
 	
-	public NatTable(final Composite parent, final int style, final ILayer layer) {
+	public NatTable(final Composite parent, final int style, final Layer layer) {
 		this(parent, style, layer, true);
 	}
 	
-	public NatTable(final Composite parent, final int style, final ILayer layer, final boolean autoconfigure) {
+	public NatTable(final Composite parent, final int style, final Layer layer, final boolean autoconfigure) {
 		super(parent, style);
 		
-		this.hDim= new NatTableDim(this, layer.getDim(HORIZONTAL));
-		this.vDim= new NatTableDim(this, layer.getDim(VERTICAL));
+		this.hDim= new NatTableLayerDim(this, layer.getDim(HORIZONTAL));
+		this.vDim= new NatTableLayerDim(this, layer.getDim(VERTICAL));
 		
 		// Disable scroll bars by default; if a Viewport is available, it will enable the scroll bars
 		disableScrollBar(getHorizontalBar());
@@ -179,7 +180,7 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 	
 	
 	@Override
-	public NatTableDim getDim(final Orientation orientation) {
+	public NatTableLayerDim getDim(final Orientation orientation) {
 		if (orientation == null) {
 			throw new NullPointerException("orientation"); //$NON-NLS-1$
 		}
@@ -201,11 +202,11 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 		}
 	}
 	
-	public ILayer getLayer() {
+	public Layer getUnderlyingLayer() {
 		return this.underlyingLayer;
 	}
 	
-	private void internalSetLayer(final ILayer layer) {
+	private void internalSetLayer(final Layer layer) {
 		if (layer != null) {
 			this.underlyingLayer= layer;
 			this.underlyingLayer.setClientAreaProvider(getClientAreaProvider());
@@ -233,17 +234,17 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 	}
 	
 	/**
-	 * @return {@link IConfigRegistry} used to hold the configuration bindings
+	 * @return {@link ConfigRegistry} used to hold the configuration bindings
 	 * 	by Layer, DisplayMode and Config labels.
 	 */
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getStyleRegistry() {
 		if (this.configRegistry == null) {
-			this.configRegistry= new ConfigRegistry();
+			this.configRegistry= new BasicConfigRegistry();
 		}
 		return this.configRegistry;
 	}
 	
-	public void setConfigRegistry(final IConfigRegistry configRegistry) {
+	public void setConfigRegistry(final ConfigRegistry configRegistry) {
 		if (this.autoconfigure) {
 			throw new IllegalStateException("May only set config registry post construction if autoconfigure is turned off"); //$NON-NLS-1$
 		}
@@ -313,15 +314,15 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 	
 	// Painting ///////////////////////////////////////////////////////////////
 	
-	public List<IOverlayPainter> getOverlayPainters() {
-		return this.overlayPainters;
+	public ImList<OverlayPainter> getOverlayPainters() {
+		return this.overlayPainters.toList();
 	}
 	
-	public void addOverlayPainter(final IOverlayPainter overlayPainter) {
+	public void addOverlayPainter(final OverlayPainter overlayPainter) {
 		this.overlayPainters.add(overlayPainter);
 	}
 	
-	public void removeOverlayPainter(final IOverlayPainter overlayPainter) {
+	public void removeOverlayPainter(final OverlayPainter overlayPainter) {
 		this.overlayPainters.remove(overlayPainter);
 	}
 	
@@ -334,16 +335,16 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 		final Rectangle eventRectangle= new Rectangle(event.x, event.y, event.width, event.height);
 		
 		if (!eventRectangle.isEmpty()) {
-			getLayerPainter().paintLayer(this, event.gc, 0, 0, eventRectangle, getConfigRegistry());
+			getLayerPainter().paintLayer(this, event.gc, 0, 0, eventRectangle, getStyleRegistry());
 		}
 	}
 	
 	@Override
-	public ILayerPainter getLayerPainter() {
+	public LayerPainter getLayerPainter() {
 		return this.layerPainter;
 	}
 	
-	public void setLayerPainter(final ILayerPainter layerPainter) {
+	public void setLayerPainter(final LayerPainter layerPainter) {
 		this.layerPainter= layerPainter;
 	}
 	
@@ -367,12 +368,12 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 		this.vDim.repaintPosition(rowPosition);
 	}
 	
-	protected void repaint(final Orientation orientation, final int start, final int size) {
+	protected void repaint(final Orientation orientation, final long start, final long size) {
 		if (orientation == HORIZONTAL) {
-			redraw(start, 0, size, safe(getHeight()), true);
+			redraw(SwtUtils.toSWT(start), 0, SwtUtils.toSWT(size), safe(getHeight()), true);
 		}
 		else {
-			redraw(0, start, safe(getWidth()), size, true);
+			redraw(0, SwtUtils.toSWT(start), safe(getWidth()), SwtUtils.toSWT(size), true);
 		}
 	}
 	
@@ -421,29 +422,25 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 		}
 		
 		if (this.underlyingLayer != null) {
-			this.underlyingLayer.configure((ConfigRegistry) getConfigRegistry(), getUiBindingRegistry());
+			this.underlyingLayer.configure(getStyleRegistry(), getUiBindingRegistry());
 		}
 		
 		for (final IConfiguration configuration : this.configurations) {
 			configuration.configureLayer(this);
-			configuration.configureRegistry(getConfigRegistry());
+			configuration.configureRegistry(getStyleRegistry());
 			configuration.configureUiBindings(getUiBindingRegistry());
 		}
-		
-		// Once everything is initialized and properly configured we will
-		// now formally initialize the grid
-		doCommand(new InitializeGridCommand(this));
 	}
 	
 	// Events /////////////////////////////////////////////////////////////////
 	
 	@Override
-	public void handleLayerEvent(final ILayerEvent event) {
-		for (final ILayerListener layerListener : this.listeners.getListeners()) {
+	public void handleLayerEvent(final LayerEvent event) {
+		for (final LayerListener layerListener : this.listeners) {
 			layerListener.handleLayerEvent(event);
 		}
 		
-		if (event instanceof IVisualChangeEvent) {
+		if (event instanceof VisualChangeEvent) {
 			this.conflaterChain.addEvent(event);
 		}
 		
@@ -466,12 +463,12 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 	
 	/**
 	 * Save the state of the table to the properties object.
-	 * {@link ILayer#saveState(String, Properties)} is invoked on all the underlying layers.
+	 * {@link Layer#saveState(String, Map)} is invoked on all the underlying layers.
 	 * This properties object will be populated with the settings of all underlying layers
-	 * and any {@link IPersistable} registered with those layers.
+	 * and any {@link Persistable} registered with those layers.
 	 */
 	@Override
-	public void saveState(final String prefix, final Properties properties) {
+	public void saveState(final String prefix, final Map<String, String> properties) {
 		BusyIndicator.showWhile(null, new Runnable() {
 			
 			@Override
@@ -483,10 +480,10 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 	
 	/**
 	 * Restore the state of the underlying layers from the values in the properties object.
-	 * @see #saveState(String, Properties)
+	 * @see #saveState(String, Map)
 	 */
 	@Override
-	public void loadState(final String prefix, final Properties properties) {
+	public void loadState(final String prefix, final Map<String, String> properties) {
 		BusyIndicator.showWhile(null, new Runnable() {
 			
 			@Override
@@ -497,51 +494,51 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 	}
 	
 	/**
-	 * @see ILayer#registerPersistable(IPersistable)
+	 * @see Layer#registerPersistable(Persistable)
 	 */
 	@Override
-	public void registerPersistable(final IPersistable persistable) {
+	public void registerPersistable(final Persistable persistable) {
 		this.persistables.add(persistable);
 	}
 	
 	@Override
-	public void unregisterPersistable(final IPersistable persistable) {
+	public void unregisterPersistable(final Persistable persistable) {
 		this.persistables.remove(persistable);
 	}
 	
 	// Command
 	
 	@Override
-	public boolean doCommand(final ILayerCommand command) {
+	public boolean doCommand(final LayerCommand command) {
 		return this.underlyingLayer.doCommand(command);
 	}
 	
 	@Override
-	public void registerCommandHandler(final ILayerCommandHandler<?> commandHandler) {
+	public void registerCommandHandler(final LayerCommandHandler<?> commandHandler) {
 		this.underlyingLayer.registerCommandHandler(commandHandler);
 	}
 	
 	@Override
-	public void unregisterCommandHandler(final Class<? extends ILayerCommand> commandClass) {
+	public void unregisterCommandHandler(final Class<? extends LayerCommand> commandClass) {
 		this.underlyingLayer.unregisterCommandHandler(commandClass);
 	}
 	
 	// Events
 	
-	private final LayerListenerList listeners= new LayerListenerList();
+	private final CopyOnWriteIdentityListSet<LayerListener> listeners= new CopyOnWriteIdentityListSet<>();
 	
 	@Override
-	public void fireLayerEvent(final ILayerEvent event) {
+	public void fireLayerEvent(final LayerEvent event) {
 		this.underlyingLayer.fireLayerEvent(event);
 	}
 	
 	@Override
-	public void addLayerListener(final ILayerListener listener) {
+	public void addLayerListener(final LayerListener listener) {
 		this.listeners.add(listener);
 	}
 	
 	@Override
-	public void removeLayerListener(final ILayerListener listener) {
+	public void removeLayerListener(final LayerListener listener) {
 		this.listeners.remove(listener);
 	}
 	
@@ -595,7 +592,7 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 	// Cell features
 	
 	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
 		return this.underlyingLayer.getCellByPosition(columnPosition, rowPosition);
 	}
 	
@@ -607,17 +604,17 @@ public class NatTable extends Canvas implements ILayer, PaintListener, ILayerLis
 	}
 	
 	@Override
-	public ILayer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
+	public Layer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
 		return this.underlyingLayer;
 	}
 	
 	@Override
-	public IClientAreaProvider getClientAreaProvider() {
+	public ClientAreaProvider getClientAreaProvider() {
 		return this.clientAreaProvider;
 	}
 	
 	@Override
-	public void setClientAreaProvider(final IClientAreaProvider clientAreaProvider) {
+	public void setClientAreaProvider(final ClientAreaProvider clientAreaProvider) {
 		this.clientAreaProvider= clientAreaProvider;
 		this.underlyingLayer.setClientAreaProvider(clientAreaProvider);
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/NatTableDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/NatTableLayerDim.java
index f368eeec..a821c3fd 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/NatTableDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/NatTableLayerDim.java
@@ -14,17 +14,19 @@
 
 package org.eclipse.statet.ecommons.waltable;
 
-import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.check;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.layer.ForwardLayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.top.TopLayerDim;
 
 
-public class NatTableDim extends ForwardLayerDim<NatTable> {
+@NonNullByDefault
+public class NatTableLayerDim extends ForwardLayerDim<NatTable> implements TopLayerDim {
 	
 	
-	public NatTableDim(final NatTable layer, final ILayerDim underlyingDim) {
+	public NatTableLayerDim(final NatTable layer, final LayerDim underlyingDim) {
 		super(layer, underlyingDim);
 	}
 	
@@ -34,14 +36,16 @@ public class NatTableDim extends ForwardLayerDim<NatTable> {
 		return this.layer;
 	}
 	
+	@Override
 	public void repaintPosition(final long position) {
 		if (position == POSITION_NA) {
 			return;
 		}
 		final long start= getPositionStart(position);
-		this.layer.repaint(this.orientation, check(start), getPositionSize(position));
+		this.layer.repaint(this.orientation, start, getPositionSize(position));
 	}
 	
+	@Override
 	public void repaintPositions(final LRange positions) {
 		if (positions.size() == 0) {
 			return;
@@ -49,7 +53,7 @@ public class NatTableDim extends ForwardLayerDim<NatTable> {
 		final long start= getPositionStart(positions.start);
 		final long end= ((positions.size() == 1) ? start : getPositionStart(positions.end - 1))
 				+ getPositionSize(positions.end - 1);
-		this.layer.repaint(this.orientation, check(start), check(end - start));
+		this.layer.repaint(this.orientation, start, end - start);
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractPositionCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractPositionCommand.java
index fc0c1b31..08aa78dc 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractPositionCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractPositionCommand.java
@@ -14,16 +14,17 @@
 package org.eclipse.statet.ecommons.waltable.command;
 
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
-public abstract class AbstractPositionCommand implements ILayerCommand {
+public abstract class AbstractPositionCommand implements LayerCommand {
 	
 	
 	private PositionCoordinate positionCoordinate;
 	
 	
-	protected AbstractPositionCommand(final ILayer layer, final long columnPosition, final long rowPosition) {
+	protected AbstractPositionCommand(final Layer layer, final long columnPosition, final long rowPosition) {
 		this.positionCoordinate= new PositionCoordinate(layer, columnPosition, rowPosition);
 	}
 	
@@ -41,7 +42,7 @@ public abstract class AbstractPositionCommand implements ILayerCommand {
 	}
 	
 	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
+	public boolean convertToTargetLayer(final Layer targetLayer) {
 		final PositionCoordinate targetPositionCoordinate= LayerCommandUtil.convertPositionToTargetContext(this.positionCoordinate, targetLayer);
 		if (targetPositionCoordinate != null) {
 			this.positionCoordinate= targetPositionCoordinate;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/DisposeResourcesCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/DisposeResourcesCommand.java
index a9f48f15..dd16cb49 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/DisposeResourcesCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/DisposeResourcesCommand.java
@@ -14,6 +14,7 @@
 package org.eclipse.statet.ecommons.waltable.command;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/LayerCommandUtil.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/LayerCommandUtil.java
index de8b4912..419d580f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/LayerCommandUtil.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/LayerCommandUtil.java
@@ -13,21 +13,21 @@
 
 package org.eclipse.statet.ecommons.waltable.command;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.statet.ecommons.waltable.coordinate.ColumnPositionCoordinate;
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
 import org.eclipse.statet.ecommons.waltable.coordinate.RowPositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.LayerUtil;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerUtils;
 
 
 public class LayerCommandUtil {
 	
-	public static PositionCoordinate convertPositionToTargetContext(final PositionCoordinate positionCoordinate, final ILayer targetLayer) {
-		final ILayer layer= positionCoordinate.getLayer();
+	public static PositionCoordinate convertPositionToTargetContext(final PositionCoordinate positionCoordinate, final Layer targetLayer) {
+		final Layer layer= positionCoordinate.getLayer();
 		
 		if (layer == targetLayer) {
 			return positionCoordinate;
@@ -45,7 +45,7 @@ public class LayerCommandUtil {
 			return null;
 		}
 		
-		final ILayer underlyingLayer= layer.getUnderlyingLayerByPosition(columnPosition, rowPosition);
+		final Layer underlyingLayer= layer.getUnderlyingLayerByPosition(columnPosition, rowPosition);
 		if (underlyingLayer == null) {
 			return null;
 		}
@@ -53,28 +53,28 @@ public class LayerCommandUtil {
 		return convertPositionToTargetContext(new PositionCoordinate(underlyingLayer, underlyingColumnPosition, underlyingRowPosition), targetLayer);
 	}
 	
-	public static ColumnPositionCoordinate convertColumnPositionToTargetContext(final ColumnPositionCoordinate columnPositionCoordinate, final ILayer targetLayer) {
+	public static ColumnPositionCoordinate convertColumnPositionToTargetContext(final ColumnPositionCoordinate columnPositionCoordinate, final Layer targetLayer) {
 		if (columnPositionCoordinate != null) {
-			final ILayer layer= columnPositionCoordinate.getLayer();
+			final Layer layer= columnPositionCoordinate.getLayer();
 			
-			final long targetPosition= LayerUtil.convertPosition(layer.getDim(HORIZONTAL),
+			final long targetPosition= LayerUtils.convertPosition(layer.getDim(HORIZONTAL),
 					columnPositionCoordinate.columnPosition, columnPositionCoordinate.columnPosition,
 					targetLayer.getDim(HORIZONTAL) );
-			return (targetPosition != ILayerDim.POSITION_NA) ?
+			return (targetPosition != LayerDim.POSITION_NA) ?
 					new ColumnPositionCoordinate(targetLayer, targetPosition) :
 					null;
 		}
 		return null;
 	}
 	
-	public static RowPositionCoordinate convertRowPositionToTargetContext(final RowPositionCoordinate rowPositionCoordinate, final ILayer targetLayer) {
+	public static RowPositionCoordinate convertRowPositionToTargetContext(final RowPositionCoordinate rowPositionCoordinate, final Layer targetLayer) {
 		if (rowPositionCoordinate != null) {
-			final ILayer layer= rowPositionCoordinate.getLayer();
+			final Layer layer= rowPositionCoordinate.getLayer();
 			
-			final long targetPosition= LayerUtil.convertPosition(layer.getDim(VERTICAL),
+			final long targetPosition= LayerUtils.convertPosition(layer.getDim(VERTICAL),
 					rowPositionCoordinate.rowPosition, rowPositionCoordinate.rowPosition,
 					targetLayer.getDim(VERTICAL) );
-			return (targetPosition != ILayerDim.POSITION_NA) ?
+			return (targetPosition != LayerDim.POSITION_NA) ?
 					new RowPositionCoordinate(targetLayer, targetPosition) :
 					null;
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractLayerConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractLayerConfiguration.java
index 5f4314d5..9835fb92 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractLayerConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractLayerConfiguration.java
@@ -13,7 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.config;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 
 
@@ -21,18 +22,18 @@ import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
  * Casts the layer to be to the type parameter for convenience. 
  * @param <L> type of the layer being configured 
  */
-public abstract class AbstractLayerConfiguration<L extends ILayer> implements IConfiguration {
+public abstract class AbstractLayerConfiguration<L extends Layer> implements IConfiguration {
 
 	@Override
 	@SuppressWarnings("unchecked")
-	public void configureLayer(final ILayer layer) {
+	public void configureLayer(final Layer layer) {
 		configureTypedLayer((L) layer);
 	}
 	
 	public abstract void configureTypedLayer(L layer);
 	
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {}
+	public void configureRegistry(final ConfigRegistry configRegistry) {}
 	
 	@Override
 	public void configureUiBindings(final UiBindingRegistry uiBindingRegistry) {}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractRegistryConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractRegistryConfiguration.java
index bde187c6..e4443565 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractRegistryConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractRegistryConfiguration.java
@@ -13,14 +13,14 @@
 
 package org.eclipse.statet.ecommons.waltable.config;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 
 
 public abstract class AbstractRegistryConfiguration implements IConfiguration {
 	
 	@Override
-	public void configureLayer(final ILayer layer) {}
+	public void configureLayer(final Layer layer) {}
 	
 	@Override
 	public void configureUiBindings(final UiBindingRegistry uiBindingRegistry) {}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractUiBindingConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractUiBindingConfiguration.java
index 7495ad6c..8dc51f52 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractUiBindingConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AbstractUiBindingConfiguration.java
@@ -13,15 +13,16 @@
 
 package org.eclipse.statet.ecommons.waltable.config;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 public abstract class AbstractUiBindingConfiguration implements IConfiguration {
 	
 	@Override
-	public void configureLayer(final ILayer layer) {}
+	public void configureLayer(final Layer layer) {}
 	
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {}
+	public void configureRegistry(final ConfigRegistry configRegistry) {}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AggregateConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AggregateConfiguration.java
index ef771bb8..c5aad69a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AggregateConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/AggregateConfiguration.java
@@ -16,7 +16,8 @@ package org.eclipse.statet.ecommons.waltable.config;
 import java.util.Collection;
 import java.util.LinkedList;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 
 
@@ -32,14 +33,14 @@ public class AggregateConfiguration implements IConfiguration {
 	}
 
 	@Override
-	public void configureLayer(final ILayer layer) {
+	public void configureLayer(final Layer layer) {
 		for (final IConfiguration configuration : this.configurations) {
 			configuration.configureLayer(layer);
 		}
 	}
 
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
+	public void configureRegistry(final ConfigRegistry configRegistry) {
 		for (final IConfiguration configuration : this.configurations) {
 			configuration.configureRegistry(configRegistry);
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/CellConfigAttributes.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/CellConfigAttributes.java
index 6b3d8f75..1517c15b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/CellConfigAttributes.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/CellConfigAttributes.java
@@ -13,17 +13,17 @@
 
 package org.eclipse.statet.ecommons.waltable.config;
 
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
 
 
 public interface CellConfigAttributes {
 	
-	ConfigAttribute<ICellPainter> CELL_PAINTER= new ConfigAttribute<>();
+	ConfigAttribute<LayerCellPainter> CELL_PAINTER= new ConfigAttribute<>();
 	
-	ConfigAttribute<IStyle> CELL_STYLE= new ConfigAttribute<>();
+	ConfigAttribute<Style> CELL_STYLE= new ConfigAttribute<>();
 	
 	ConfigAttribute<IDisplayConverter> DISPLAY_CONVERTER= new ConfigAttribute<>();
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/ConfigRegistry.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/ConfigRegistry.java
deleted file mode 100644
index 9cb5ad79..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/ConfigRegistry.java
+++ /dev/null
@@ -1,149 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.config;
-
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
-import org.eclipse.statet.ecommons.waltable.style.DefaultDisplayModeOrdering;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.IDisplayModeLookupStrategy;
-
-
-public class ConfigRegistry implements IConfigRegistry {
-	
-	
-	// Map<configAttributeType, Map<displayMode, Map<configLabel, value>>>
-	final Map<ConfigAttribute<?>, Map<DisplayMode, Map<String, ?>>> configRegistry= new HashMap<>();
-	
-	private IDisplayModeLookupStrategy displayModeLookupStrategy= new DefaultDisplayModeOrdering();
-	
-	
-	public ConfigRegistry() {
-	}
-	
-	
-	@Override
-	public IDisplayModeLookupStrategy getDisplayModeOrdering() {
-		return this.displayModeLookupStrategy;
-	}
-	
-	public void setDisplayModeOrdering(final IDisplayModeLookupStrategy displayModeLookupStrategy) {
-		this.displayModeLookupStrategy= displayModeLookupStrategy;
-	}
-	
-	
-	@Override
-	public <T> T getConfigAttribute(final ConfigAttribute<T> configAttribute,
-			final DisplayMode targetDisplayMode, final String...configLabels) {
-		return getConfigAttribute(configAttribute, targetDisplayMode, Arrays.asList(configLabels));
-	}
-	
-	@Override
-	@SuppressWarnings("unchecked")
-	public <T> T getConfigAttribute(final ConfigAttribute<T> configAttribute,
-			final DisplayMode targetDisplayMode, final List<String> configLabels) {
-		T attributeValue= null;
-		
-		final Map<DisplayMode, Map<String, ?>> displayModeConfigAttributeMap= this.configRegistry.get(configAttribute);
-		if (displayModeConfigAttributeMap != null) {
-			for (final DisplayMode displayMode : this.displayModeLookupStrategy.getDisplayModeOrdering(targetDisplayMode)) {
-				final Map<String, T> configAttributeMap= (Map<String, T>) displayModeConfigAttributeMap.get(displayMode);
-				if (configAttributeMap != null) {
-					for (final String configLabel : configLabels) {
-						attributeValue= configAttributeMap.get(configLabel);
-						if (attributeValue != null) {
-							return attributeValue;
-						}
-					}
-					
-					// default config type
-					attributeValue= configAttributeMap.get(null);
-					if (attributeValue != null) {
-						return attributeValue;
-					}
-				}
-			}
-		}
-		
-		return attributeValue;
-	}
-	
-	@Override
-	@SuppressWarnings("unchecked")
-	public <T> T getSpecificConfigAttribute(final ConfigAttribute<T> configAttribute,
-			final DisplayMode displayMode, final String configLabel) {
-		T attributeValue= null;
-		
-		final Map<DisplayMode, Map<String, ?>> displayModeConfigAttributeMap= this.configRegistry.get(configAttribute);
-		if (displayModeConfigAttributeMap != null) {
-			final Map<String, T> configAttributeMap= (Map<String, T>) displayModeConfigAttributeMap.get(displayMode);
-			if (configAttributeMap != null) {
-				attributeValue= configAttributeMap.get(configLabel);
-				if (attributeValue != null) {
-					return attributeValue;
-				}
-			}
-		}
-		
-		return attributeValue;
-	}
-	
-	@Override
-	public <T> void registerConfigAttribute(final ConfigAttribute<T> configAttribute, final T attributeValue) {
-		registerConfigAttribute(configAttribute, attributeValue, DisplayMode.NORMAL);
-	}
-	
-	@Override
-	public <T> void registerConfigAttribute(final ConfigAttribute<T> configAttribute, final T attributeValue,
-			final DisplayMode displayMode) {
-		registerConfigAttribute(configAttribute, attributeValue, displayMode, null);
-	}
-	
-	@Override
-	@SuppressWarnings("unchecked")
-	public <T> void registerConfigAttribute(final ConfigAttribute<T> configAttribute, final T attributeValue,
-			final DisplayMode displayMode, final String configLabel) {
-		Map<DisplayMode, Map<String, ?>> displayModeConfigAttributeMap= this.configRegistry.get(configAttribute);
-		if (displayModeConfigAttributeMap == null) {
-			displayModeConfigAttributeMap= new HashMap<>();
-			this.configRegistry.put(configAttribute, displayModeConfigAttributeMap);
-		}
-		
-		Map<String, T> configAttributeMap= (Map<String, T>) displayModeConfigAttributeMap.get(displayMode);
-		if (configAttributeMap == null) {
-			configAttributeMap= new HashMap<>();
-			displayModeConfigAttributeMap.put(displayMode, configAttributeMap);
-		}
-		
-		configAttributeMap.put(configLabel, attributeValue);
-	}
-	
-	@Override
-	@SuppressWarnings("unchecked")
-	public <T> void unregisterConfigAttribute(final ConfigAttribute<T> configAttributeType,
-			final DisplayMode displayMode, final String configLabel) {
-		final Map<DisplayMode, Map<String, ?>> displayModeConfigAttributeMap= this.configRegistry.get(configAttributeType);
-		if (displayModeConfigAttributeMap != null) {
-			final Map<String, T> configAttributeMap= (Map<String, T>) displayModeConfigAttributeMap.get(displayMode);
-			if (configAttributeMap != null) {
-				configAttributeMap.remove(configLabel);
-			}
-		}
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/ContextualEditableRule.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/ContextualEditableRule.java
index addc20db..36111a72 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/ContextualEditableRule.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/ContextualEditableRule.java
@@ -13,7 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.config;
 
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 public abstract class ContextualEditableRule implements IEditableRule {
@@ -24,6 +25,6 @@ public abstract class ContextualEditableRule implements IEditableRule {
 	}
 
 	@Override
-	public abstract boolean isEditable(ILayerCell cell, IConfigRegistry configRegistry);
+	public abstract boolean isEditable(LayerCell cell, ConfigRegistry configRegistry);
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/DefaultEditableRule.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/DefaultEditableRule.java
index f97e6b59..d3574196 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/DefaultEditableRule.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/DefaultEditableRule.java
@@ -13,7 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.config;
 
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 public class DefaultEditableRule implements IEditableRule {
@@ -25,7 +26,7 @@ public class DefaultEditableRule implements IEditableRule {
 	}
 	
 	@Override
-	public boolean isEditable(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	public boolean isEditable(final LayerCell cell, final ConfigRegistry configRegistry) {
 		return this.defaultEditable;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/DefaultNatTableStyleConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/DefaultNatTableStyleConfiguration.java
index d49c627e..9bb3c904 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/DefaultNatTableStyleConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/DefaultNatTableStyleConfiguration.java
@@ -16,15 +16,16 @@ package org.eclipse.statet.ecommons.waltable.config;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.Font;
 
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.VerticalAlignment;
 import org.eclipse.statet.ecommons.waltable.data.convert.DefaultDisplayConverter;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.TextPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.decorator.LineBorderDecorator;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
-import org.eclipse.statet.ecommons.waltable.style.Style;
-import org.eclipse.statet.ecommons.waltable.style.VerticalAlignment;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -33,30 +34,30 @@ public class DefaultNatTableStyleConfiguration extends AbstractRegistryConfigura
 	public Color bgColor= GUIHelper.COLOR_WHITE;
 	public Color fgColor= GUIHelper.COLOR_BLACK;
 	public Color gradientBgColor= GUIHelper.COLOR_WHITE;
-	public Color gradientFgColor= GUIHelper.getColor(136, 212, 215);
+	public Color gradientFgColor= new Color(136, 212, 215);
 	public Font font= GUIHelper.DEFAULT_FONT;
 	public HorizontalAlignment hAlign= HorizontalAlignment.CENTER;
 	public VerticalAlignment vAlign= VerticalAlignment.MIDDLE;
 	public BorderStyle borderStyle= null;
 
-	public ICellPainter cellPainter= new LineBorderDecorator(new TextPainter());
+	public LayerCellPainter layerCellPainter= new LineBorderDecorator(new TextPainter());
 	
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_PAINTER, this.cellPainter);
-
-		final Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR, this.bgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.FOREGROUND_COLOR, this.fgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.GRADIENT_BACKGROUND_COLOR, this.gradientBgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.GRADIENT_FOREGROUND_COLOR, this.gradientFgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.FONT, this.font);
-		cellStyle.setAttributeValue(CellStyleAttributes.HORIZONTAL_ALIGNMENT, this.hAlign);
-		cellStyle.setAttributeValue(CellStyleAttributes.VERTICAL_ALIGNMENT, this.vAlign);
-		cellStyle.setAttributeValue(CellStyleAttributes.BORDER_STYLE, this.borderStyle);
+	public void configureRegistry(final ConfigRegistry configRegistry) {
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_PAINTER, this.layerCellPainter);
+
+		final BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR, this.bgColor);
+		cellStyle.setAttributeValue(CellStyling.FOREGROUND_COLOR, this.fgColor);
+		cellStyle.setAttributeValue(CellStyling.GRADIENT_BACKGROUND_COLOR, this.gradientBgColor);
+		cellStyle.setAttributeValue(CellStyling.GRADIENT_FOREGROUND_COLOR, this.gradientFgColor);
+		cellStyle.setAttributeValue(CellStyling.FONT, this.font);
+		cellStyle.setAttributeValue(CellStyling.HORIZONTAL_ALIGNMENT, this.hAlign);
+		cellStyle.setAttributeValue(CellStyling.VERTICAL_ALIGNMENT, this.vAlign);
+		cellStyle.setAttributeValue(CellStyling.BORDER_STYLE, this.borderStyle);
 		
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle);
 	
-		configRegistry.registerConfigAttribute(CellConfigAttributes.DISPLAY_CONVERTER, new DefaultDisplayConverter());
+		configRegistry.registerAttribute(CellConfigAttributes.DISPLAY_CONVERTER, new DefaultDisplayConverter());
 	}
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IConfiguration.java
index 2a3af1cf..de7f50bb 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IConfiguration.java
@@ -14,10 +14,11 @@
 package org.eclipse.statet.ecommons.waltable.config;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.AbstractLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 import org.eclipse.statet.ecommons.waltable.data.validate.IDataValidator;
-import org.eclipse.statet.ecommons.waltable.layer.AbstractLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 
 
@@ -26,21 +27,21 @@ import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
  * These will be processed when {@link NatTable#configure()} is invoked.
  * 
  * Default configurations are added to most layers {@link AbstractLayer#addConfiguration(IConfiguration)}.
- * You can turn off default configuration for an {@link ILayer} by setting auto configure to false
+ * You can turn off default configuration for an {@link Layer} by setting auto configure to false
  * in the constructor.
  */
 public interface IConfiguration {
 
-	public void configureLayer(ILayer layer);
+	public void configureLayer(Layer layer);
 
 	/**
-	 * Configure NatTable's {@link IConfigRegistry} upon receiving this call back.
-	 * A mechanism to plug-in custom {@link ICellPainter}, {@link IDataValidator} etc.
+	 * Configure NatTable's {@link ConfigRegistry} upon receiving this call back.
+	 * A mechanism to plug-in custom {@link LayerCellPainter}, {@link IDataValidator} etc.
 	 */
-	public void configureRegistry(IConfigRegistry configRegistry);
+	public void configureRegistry(ConfigRegistry configRegistry);
 
 	/**
-	 * Configure NatTable's {@link IConfigRegistry} upon receiving this call back
+	 * Configure NatTable's {@link ConfigRegistry} upon receiving this call back
 	 * A mechanism to customize key/mouse bindings.
 	 */
 	public void configureUiBindings(UiBindingRegistry uiBindingRegistry);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IEditableRule.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IEditableRule.java
index 09b7fee4..9e73bcb0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IEditableRule.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IEditableRule.java
@@ -13,7 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.config;
 
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 public interface IEditableRule {
@@ -22,7 +23,7 @@ public interface IEditableRule {
 	IEditableRule ALWAYS_EDITABLE= new IEditableRule() {
 		
 		@Override
-		public boolean isEditable(final ILayerCell cell, final IConfigRegistry configRegistry) {
+		public boolean isEditable(final LayerCell cell, final ConfigRegistry configRegistry) {
 			return true;
 		}
 		
@@ -31,14 +32,14 @@ public interface IEditableRule {
 	IEditableRule NEVER_EDITABLE= new IEditableRule() {
 		
 		@Override
-		public boolean isEditable(final ILayerCell cell, final IConfigRegistry configRegistry) {
+		public boolean isEditable(final LayerCell cell, final ConfigRegistry configRegistry) {
 			return false;
 		}
 		
 	};
 	
 	
-	boolean isEditable(ILayerCell cell, IConfigRegistry configRegistry);
+	boolean isEditable(LayerCell cell, ConfigRegistry configRegistry);
 	
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/LayoutSizeConfig.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/LayoutSizeConfig.java
index 9e60f0b4..ead744f0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/LayoutSizeConfig.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/LayoutSizeConfig.java
@@ -14,7 +14,7 @@
 
 package org.eclipse.statet.ecommons.waltable.config;
 
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
 
 
 public class LayoutSizeConfig {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/AbstractEventConflater.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/AbstractEventConflater.java
index c6c9de6f..ebd08e9f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/AbstractEventConflater.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/AbstractEventConflater.java
@@ -16,15 +16,15 @@ package org.eclipse.statet.ecommons.waltable.conflation;
 import java.util.LinkedList;
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
 
 
 public abstract class AbstractEventConflater implements IEventConflater {
 
-	protected List<ILayerEvent> queue= new LinkedList<>();
+	protected List<LayerEvent> queue= new LinkedList<>();
 
 	@Override
-	public void addEvent(final ILayerEvent event){
+	public void addEvent(final LayerEvent event){
 		this.queue.add(event);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/EventConflaterChain.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/EventConflaterChain.java
index 4c0687c1..113bfbe4 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/EventConflaterChain.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/EventConflaterChain.java
@@ -17,7 +17,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.concurrent.ScheduledFuture;
 
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
 import org.eclipse.statet.ecommons.waltable.util.Scheduler;
 
 
@@ -69,7 +69,7 @@ public class EventConflaterChain implements IEventConflater {
 	}
 	
 	@Override
-	public void addEvent(final ILayerEvent event) {
+	public void addEvent(final LayerEvent event) {
 		for (final IEventConflater eventConflater : this.chain) {
 			eventConflater.addEvent(event);
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/IEventConflater.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/IEventConflater.java
index d0652247..bacafd95 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/IEventConflater.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/IEventConflater.java
@@ -13,7 +13,7 @@
 
 package org.eclipse.statet.ecommons.waltable.conflation;
 
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
 
 
 /**
@@ -23,7 +23,7 @@ import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
  */
 public interface IEventConflater {
 
-	public abstract void addEvent(ILayerEvent event);
+	public abstract void addEvent(LayerEvent event);
 
 	public abstract void clearQueue();
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/VisualChangeEventConflater.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/VisualChangeEventConflater.java
index e851c5cd..48054948 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/VisualChangeEventConflater.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/conflation/VisualChangeEventConflater.java
@@ -14,8 +14,8 @@
 package org.eclipse.statet.ecommons.waltable.conflation;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
-import org.eclipse.statet.ecommons.waltable.layer.event.IVisualChangeEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.VisualChangeEvent;
 
 
 /**
@@ -33,8 +33,8 @@ public class VisualChangeEventConflater extends AbstractEventConflater {
 	}
 	
 	@Override
-	public void addEvent(final ILayerEvent event) {
-		if(event instanceof IVisualChangeEvent){
+	public void addEvent(final LayerEvent event) {
+		if (event instanceof VisualChangeEvent){
 			super.addEvent(event);
 		}
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/ColumnPositionCoordinate.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/ColumnPositionCoordinate.java
index 0c54087e..013bc65f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/ColumnPositionCoordinate.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/ColumnPositionCoordinate.java
@@ -13,24 +13,24 @@
 
 package org.eclipse.statet.ecommons.waltable.coordinate;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 public final class ColumnPositionCoordinate {
 
 
-	private final ILayer layer;
+	private final Layer layer;
 
 	public final long columnPosition;
 
 
-	public ColumnPositionCoordinate(final ILayer layer, final long columnPosition) {
+	public ColumnPositionCoordinate(final Layer layer, final long columnPosition) {
 		this.layer= layer;
 		this.columnPosition= columnPosition;
 	}
 
 
-	public ILayer getLayer() {
+	public Layer getLayer() {
 		return this.layer;
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/Direction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/Direction.java
deleted file mode 100644
index f8a269b5..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/Direction.java
+++ /dev/null
@@ -1,94 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.coordinate;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
-
-
-public enum Direction {
-	
-	
-	LEFT (HORIZONTAL),
-	RIGHT (HORIZONTAL),
-	UP (VERTICAL),
-	DOWN (VERTICAL);
-	
-	
-	public static Direction backward(final Orientation orientation) {
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
-		}
-		return (orientation == HORIZONTAL) ? LEFT : UP;
-	}
-	
-	public static Direction forward(final Orientation orientation) {
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
-		}
-		return (orientation == HORIZONTAL) ? RIGHT : LEFT;
-	}
-	
-	
-	private final Orientation orientation;
-	
-	
-	private Direction(final Orientation orientation) {
-		this.orientation= orientation;
-	}
-	
-	
-	public Orientation getOrientation() {
-		return this.orientation;
-	}
-	
-	public boolean isBackward() {
-		switch (this) {
-		case LEFT:
-		case UP:
-			return true;
-		case RIGHT:
-		case DOWN:
-		default:
-			return false;
-		}
-	}
-	
-	public boolean isForward() {
-		switch (this) {
-		case RIGHT:
-		case DOWN:
-			return true;
-		case LEFT:
-		case UP:
-		default:
-			return false;
-		}
-	}
-	
-	public Direction getOpposite() {
-		switch (this) {
-		case LEFT:
-			return RIGHT;
-		case RIGHT:
-			return LEFT;
-		case UP:
-			return DOWN;
-		case DOWN:
-		default:
-			return UP;
-		}
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PixelOutOfBoundsException.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PixelOutOfBoundsException.java
deleted file mode 100644
index 81845b07..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PixelOutOfBoundsException.java
+++ /dev/null
@@ -1,46 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2013, 2021 Stephan Wahlbrink and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
- # which is available at https://www.apache.org/licenses/LICENSE-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
- # 
- # Contributors:
- #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.coordinate;
-
-
-public class PixelOutOfBoundsException extends IllegalArgumentException {
-	
-	
-	private static final long serialVersionUID= 1L;
-	
-	
-	public static PixelOutOfBoundsException pixel(final long pixel,
-			final Orientation orientation) {
-		return new PixelOutOfBoundsException("pixel", pixel, orientation); //$NON-NLS-1$
-	}
-	
-	public static PixelOutOfBoundsException pixel(final long pixel) {
-		return new PixelOutOfBoundsException("pixel", pixel); //$NON-NLS-1$
-	}
-	
-	public PixelOutOfBoundsException(final String message) {
-		super(message);
-	}
-	
-	public PixelOutOfBoundsException(final String label, final long position) {
-		super(label + ": " + position); //$NON-NLS-1$
-	}
-	
-	public PixelOutOfBoundsException(final String label, final long position,
-			final Orientation orientation) {
-		super(label + " (" + orientation + "): " + position); //$NON-NLS-1$ //$NON-NLS-2$
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PositionCoordinate.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PositionCoordinate.java
index 2857a113..8d6810d3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PositionCoordinate.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PositionCoordinate.java
@@ -13,19 +13,19 @@
 
 package org.eclipse.statet.ecommons.waltable.coordinate;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 public final class PositionCoordinate {
 	
 	
-	private final ILayer layer;
+	private final Layer layer;
 	
 	public long columnPosition;
 	public long rowPosition;
 	
 	
-	public PositionCoordinate(final ILayer layer, final long columnPosition, final long rowPosition) {
+	public PositionCoordinate(final Layer layer, final long columnPosition, final long rowPosition) {
 		this.layer= layer;
 		this.columnPosition= columnPosition;
 		this.rowPosition= rowPosition;
@@ -38,7 +38,7 @@ public final class PositionCoordinate {
 	}
 	
 	
-	public ILayer getLayer() {
+	public Layer getLayer() {
 		return this.layer;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/RowPositionCoordinate.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/RowPositionCoordinate.java
index 951ba11a..056fd033 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/RowPositionCoordinate.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/RowPositionCoordinate.java
@@ -13,24 +13,24 @@
 
 package org.eclipse.statet.ecommons.waltable.coordinate;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 public final class RowPositionCoordinate {
 	
 	
-	private final ILayer layer;
+	private final Layer layer;
 	
 	public final long rowPosition;
 	
 	
-	public RowPositionCoordinate(final ILayer layer, final long rowPosition) {
+	public RowPositionCoordinate(final Layer layer, final long rowPosition) {
 		this.layer= layer;
 		this.rowPosition= rowPosition;
 	}
 	
 	
-	public ILayer getLayer() {
+	public Layer getLayer() {
 		return this.layer;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/IPersistable.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/Persistable.java
index 1f56739d..69a7df88 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/IPersistable.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/Persistable.java
@@ -11,46 +11,54 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.persistence;
+package org.eclipse.statet.ecommons.waltable.core;
 
-import java.util.Properties;
+import java.util.Map;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 
 /**
- * Instances implementing this interface can save and load their
- * state from a properties file. The state is therefore a collection
- * of key value pairs.
+ * Instances implementing this interface can save and load their state from
+ * a properties map. The state is therefore a collection of key value pairs.
  */
-public interface IPersistable {
-
+@NonNullByDefault
+public interface Persistable {
+	
 	/**
 	 * Separator used for properties. Example: .BODY.columnWidth.resizableByDefault
 	 */
-	public static final String DOT= "."; //$NON-NLS-1$
-
+	static final String DOT= "."; //$NON-NLS-1$
+	
 	/**
 	 * Separator used for values. Example: 0,1,2,3,4
 	 */
-	public static final String VALUE_SEPARATOR= ","; //$NON-NLS-1$
-
+	static final String VALUE_SEPARATOR= ","; //$NON-NLS-1$
+	
+	
 	/**
-	 * Saves the state to the given Properties using the specified prefix. 
-	 * Note: The prefix must be prepended to the property key to support multiple states
-	 * 		 within one Properties instance.
-	 * @param prefix The prefix to use for the state keys. Is also used as the state
-	 * 			configuration name.
-	 * @param properties The Properties instance to save the state to. 
+	 * Saves the state to the given Properties using the specified prefix.
+	 * 
+	 * Note: The prefix must be prepended to the property key to support
+	 *     multiple states within one properties store.
+	 * 
+	 * @param prefix the prefix to use for the state keys. It is also used as
+	 *     the state configuration name.
+	 * @param properties the properties to save the state to.
 	 */
-	public void saveState(String prefix, Properties properties);
-
+	void saveState(String prefix, Map<String, String> properties);
+	
 	/**
-	 * Restore the state out of the given Properties identified by the specified prefix. 
+	 * Restore the state out of the given Properties identified by the
+	 * specified prefix.
+	 * 
 	 * Note: The prefix must be prepended to the property key to support multiple states
-	 * 		 within one Properties instance.
-	 * @param prefix The prefix to use for the state keys. Is also used as the state
-	 * 			configuration name.
-	 * @param properties The Properties instance to load the state from. 
+	 * within one properties store.
+	 * 
+	 * @param prefix the prefix to use for the state keys. It is also used as
+	 *     the state configuration name.
+	 * @param properties the properties to load the state from.
 	 */
-	public void loadState(String prefix, Properties properties);
+	void loadState(String prefix, Map<String, String> properties);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractContextFreeCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractContextFreeCommand.java
index e7fc28d4..7936b9a9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractContextFreeCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractContextFreeCommand.java
@@ -11,15 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.core.command;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
-public abstract class AbstractContextFreeCommand implements ILayerCommand {
+
+@NonNullByDefault
+public abstract class AbstractContextFreeCommand implements LayerCommand {
+	
 	
 	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
+	public boolean convertToTargetLayer(final Layer targetLayer) {
 		return true;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractDimPositionCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractDimPositionCommand.java
index 61df739b..efff90cf 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractDimPositionCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractDimPositionCommand.java
@@ -12,23 +12,26 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.core.command;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.LayerUtil;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerUtils;
 
-public abstract class AbstractDimPositionCommand implements ILayerCommand {
+
+@NonNullByDefault
+public abstract class AbstractDimPositionCommand implements LayerCommand {
 	
 	
-	private ILayerDim layerDim;
+	private LayerDim layerDim;
 	
 	private long position;
 	
 	
-	protected AbstractDimPositionCommand(final ILayerDim layerDim, final long position) {
+	protected AbstractDimPositionCommand(final LayerDim layerDim, final long position) {
 		this.layerDim= layerDim;
 		this.position= position;
 	}
@@ -43,7 +46,7 @@ public abstract class AbstractDimPositionCommand implements ILayerCommand {
 		return this.layerDim.getOrientation();
 	}
 	
-	public final ILayerDim getDim() {
+	public final LayerDim getDim() {
 		return this.layerDim;
 	}
 	
@@ -53,19 +56,19 @@ public abstract class AbstractDimPositionCommand implements ILayerCommand {
 	
 	
 	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
-		final ILayerDim targetDim= targetLayer.getDim(getOrientation());
-		if (this.layerDim == targetDim) {
+	public boolean convertToTargetLayer(final Layer targetLayer) {
+		final LayerDim targetLayerDim= targetLayer.getDim(getOrientation());
+		if (this.layerDim == targetLayerDim) {
 			return true;
 		}
 		
-		return convertToTargetLayer(this.layerDim, this.position, targetDim);
+		return convertToTargetLayer(this.layerDim, this.position, targetLayerDim);
 	}
 	
-	protected boolean convertToTargetLayer(final ILayerDim dim,
-			final long position, final ILayerDim targetDim) {
-		final long targetPosition= LayerUtil.convertPosition(dim, position, position, targetDim);
-		if (targetPosition == ILayerDim.POSITION_NA) {
+	protected boolean convertToTargetLayer(final LayerDim dim,
+			final long position, final LayerDim targetDim) {
+		final long targetPosition= LayerUtils.convertPosition(dim, position, position, targetDim);
+		if (targetPosition == LayerDim.POSITION_NA) {
 			return false;
 		}
 		
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractDimPositionsCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractDimPositionsCommand.java
index 621f10a8..962a18cc 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractDimPositionsCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractDimPositionsCommand.java
@@ -12,38 +12,41 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.core.command;
 
 import java.util.Collection;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.LayerUtil;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerUtils;
 
-public abstract class AbstractDimPositionsCommand implements ILayerCommand {
+
+@NonNullByDefault
+public abstract class AbstractDimPositionsCommand implements LayerCommand {
 	
 	protected static final long NO_REF= Long.MIN_VALUE + 1;
 	
 	
-	private ILayerDim layerDim;
+	private LayerDim layerDim;
 	
 	private long refPosition;
 	
 	private Collection<LRange> positions;
 	
 	
-	protected AbstractDimPositionsCommand(final ILayerDim layerDim,
+	protected AbstractDimPositionsCommand(final LayerDim layerDim,
 			final long refPosition, final Collection<LRange> positions) {
 		this.layerDim= layerDim;
 		this.refPosition= refPosition;
 		this.positions= positions;
 	}
 	
-	protected AbstractDimPositionsCommand(final ILayerDim layerDim,
+	protected AbstractDimPositionsCommand(final LayerDim layerDim,
 			final Collection<LRange> positions) {
 		this(layerDim, NO_REF, positions);
 	}
@@ -59,7 +62,7 @@ public abstract class AbstractDimPositionsCommand implements ILayerCommand {
 		return this.layerDim.getOrientation();
 	}
 	
-	public final ILayerDim getDim() {
+	public final LayerDim getDim() {
 		return this.layerDim;
 	}
 	
@@ -73,48 +76,48 @@ public abstract class AbstractDimPositionsCommand implements ILayerCommand {
 	
 	
 	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
-		final ILayerDim targetDim= targetLayer.getDim(getOrientation());
-		if (this.layerDim == targetDim) {
+	public boolean convertToTargetLayer(final Layer targetLayer) {
+		final LayerDim targetLayerDim= targetLayer.getDim(getOrientation());
+		if (this.layerDim == targetLayerDim) {
 			return true;
 		}
 		
-		return convertToTargetLayer(this.layerDim, this.refPosition, targetDim);
+		return convertToTargetLayer(this.layerDim, this.refPosition, targetLayerDim);
 	}
 	
-	protected boolean convertToTargetLayer(final ILayerDim dim,
-			final long refPosition, final ILayerDim targetDim) {
+	protected boolean convertToTargetLayer(final LayerDim dim,
+			final long refPosition, final LayerDim targetDim) {
 		final long targetRefPosition;
 		final LRangeList targetPositions= new LRangeList();
 		if (refPosition == NO_REF) {
 			targetRefPosition= NO_REF;
 			for (final LRange lRange : this.positions) {
 				for (long position= lRange.start; position < lRange.end; position++) {
-					final long targetPosition= LayerUtil.convertPosition(dim,
+					final long targetPosition= LayerUtils.convertPosition(dim,
 							position, position, targetDim );
-					if (targetPosition != ILayerDim.POSITION_NA) {
+					if (targetPosition != LayerDim.POSITION_NA) {
 						targetPositions.values().add(targetPosition);
 					}
 				}
 			}
 		}
-		else if (refPosition != ILayerDim.POSITION_NA) {
-			targetRefPosition= LayerUtil.convertPosition(dim, refPosition, refPosition, targetDim);
-			if (targetRefPosition == ILayerDim.POSITION_NA) {
+		else if (refPosition != LayerDim.POSITION_NA) {
+			targetRefPosition= LayerUtils.convertPosition(dim, refPosition, refPosition, targetDim);
+			if (targetRefPosition == LayerDim.POSITION_NA) {
 				return false;
 			}
 			for (final LRange lRange : this.positions) {
 				for (long position= lRange.start; position < lRange.end; position++) {
-					final long targetPosition= LayerUtil.convertPosition(dim,
+					final long targetPosition= LayerUtils.convertPosition(dim,
 							refPosition, position, targetDim );
-					if (targetPosition != ILayerDim.POSITION_NA) {
+					if (targetPosition != LayerDim.POSITION_NA) {
 						targetPositions.values().add(targetPosition);
 					}
 				}
 			}
 		}
 		else {
-			targetRefPosition= ILayerDim.POSITION_NA;
+			targetRefPosition= LayerDim.POSITION_NA;
 		}
 		
 		if (targetPositions.isEmpty()) {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractLayerCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractLayerCommandHandler.java
index c395edf0..36e942c3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractLayerCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractLayerCommandHandler.java
@@ -11,16 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.core.command;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
-public abstract class AbstractLayerCommandHandler<T extends ILayerCommand> implements ILayerCommandHandler<T> {
+
+@NonNullByDefault
+public abstract class AbstractLayerCommandHandler<T extends LayerCommand> implements LayerCommandHandler<T> {
 	
 	
 	@Override
-	public final boolean doCommand(final ILayer targetLayer, final T command) {
+	public final boolean doCommand(final Layer targetLayer, final T command) {
 		if (command.convertToTargetLayer(targetLayer)) {
 			return doCommand(command);
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractRelativeCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractRelativeCommand.java
index 490fae0e..c7e63af9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/AbstractRelativeCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/AbstractRelativeCommand.java
@@ -12,11 +12,16 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.core.command;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
+
+
+@NonNullByDefault
 public abstract class AbstractRelativeCommand extends AbstractContextFreeCommand {
 	
 	
@@ -26,10 +31,7 @@ public abstract class AbstractRelativeCommand extends AbstractContextFreeCommand
 	
 	
 	public AbstractRelativeCommand(final Direction direction, final long stepCount) {
-		if (direction == null) {
-			throw new NullPointerException("direction"); //$NON-NLS-1$
-		}
-		this.direction= direction;
+		this.direction= nonNullAssert(direction);
 		this.stepCount= stepCount;
 	}
 	
@@ -38,9 +40,6 @@ public abstract class AbstractRelativeCommand extends AbstractContextFreeCommand
 		this.stepCount= command.stepCount;
 	}
 	
-	@Override
-	public abstract AbstractRelativeCommand cloneCommand();
-	
 	
 	public Direction getDirection() {
 		return this.direction;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/ILayerCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/LayerCommand.java
index b3a5f8ad..894c3f12 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/ILayerCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/LayerCommand.java
@@ -11,20 +11,23 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.core.command;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.grid.layer.GridLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 /**
- * Commands are fired by NatTable in response to user actions.
- * Commands flow down the layer stack until they are processed by an
- * {@link ILayer} or an associated {@link ILayerCommandHandler}. 
- * Commands can be fired from code by invoking {@link NatTable#doCommand(ILayerCommand)} 
+ * A command triggers a specific operation on a layer or behaviour of the table.
+ * 
+ * Commands flow down the layer stack until they are processed by a {@link Layer}
+ * or an associated {@link LayerCommandHandler}.
+ * Commands can be fired from code by invoking {@link NatTable#doCommand(LayerCommand)}.
  */
-public interface ILayerCommand {
+@NonNullByDefault
+public interface LayerCommand {
 	
 	
 	/**
@@ -36,15 +39,14 @@ public interface ILayerCommand {
 	 * @param targetLayer the target layer
 	 * @return true if the command is valid after conversion, false if the command is no longer valid.
 	 */
-	public boolean convertToTargetLayer(ILayer targetLayer);
+	boolean convertToTargetLayer(Layer targetLayer);
 	
 	/**
 	 * Same semantics as {@link Object#clone()}
 	 * Used to make a copies of the command if has to passed to different layer stacks.
 	 * 
-	 * @see GridLayer#doCommand(ILayerCommand)
 	 * @return a cloned instance of the command
 	 */
-	public ILayerCommand cloneCommand();
+	LayerCommand cloneCommand();
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/ILayerCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/LayerCommandHandler.java
index 3c0336a8..5bf3f535 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/ILayerCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/command/LayerCommandHandler.java
@@ -11,21 +11,30 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.core.command;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
-public interface ILayerCommandHandler <T extends ILayerCommand> {
+
+@NonNullByDefault
+public interface LayerCommandHandler <T extends LayerCommand> {
 	
 	
-	public Class<T> getCommandClass();
+	Class<T> getCommandClass();
 	
 	/**
 	 * @param targetLayer the target layer
 	 * @param command the command
 	 * @return true if the command has been handled, false otherwise
 	 */
-	public boolean doCommand(ILayer targetLayer, T command);
+	default boolean doCommand(final Layer targetLayer, final T command) {
+		return executeCommand(command);
+	}
+	
+	default boolean executeCommand(final T command) {
+		throw new UnsupportedOperationException();
+	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/BasicConfigRegistry.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/BasicConfigRegistry.java
new file mode 100644
index 00000000..7f058baf
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/BasicConfigRegistry.java
@@ -0,0 +1,150 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.config;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.lang.NonNull;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+
+@NonNullByDefault
+public class BasicConfigRegistry implements ConfigRegistry {
+	
+	
+	private DisplayModeLookupStrategy displayModeLookupStrategy= new DefaultDisplayModeOrdering();
+	
+	private final Map<ConfigAttribute<?>, Map<DisplayMode, Map<String, ?>>> configRegistry= new HashMap<>();
+	
+	
+	public BasicConfigRegistry() {
+	}
+	
+	
+	@Override
+	public DisplayModeLookupStrategy getDisplayModeOrdering() {
+		return this.displayModeLookupStrategy;
+	}
+	
+	public void setDisplayModeOrdering(final DisplayModeLookupStrategy displayModeLookupStrategy) {
+		this.displayModeLookupStrategy= nonNullAssert(displayModeLookupStrategy);
+	}
+	
+	
+	@Override
+	public <T> @Nullable T getAttribute(final ConfigAttribute<T> configAttribute,
+			final DisplayMode targetDisplayMode, final @NonNull String... configLabels) {
+		return getAttribute(configAttribute, targetDisplayMode, ImCollections.newList(configLabels));
+	}
+	
+	@Override
+	@SuppressWarnings("unchecked")
+	public <T> @Nullable T getAttribute(final ConfigAttribute<T> configAttribute,
+			final DisplayMode targetDisplayMode, final List<String> configLabels) {
+		@Nullable T attributeValue= null;
+		
+		final Map<DisplayMode, Map<String, ?>> displayModeAttributeMap= this.configRegistry.get(configAttribute);
+		if (displayModeAttributeMap != null) {
+			for (final DisplayMode displayMode : this.displayModeLookupStrategy.getDisplayModeOrdering(targetDisplayMode)) {
+				final Map<String, T> configAttributeMap= (Map<String, T>)displayModeAttributeMap.get(displayMode);
+				if (configAttributeMap != null) {
+					for (final String configLabel : configLabels) {
+						attributeValue= configAttributeMap.get(configLabel);
+						if (attributeValue != null) {
+							return attributeValue;
+						}
+					}
+					
+					// default config type
+					attributeValue= configAttributeMap.get(null);
+					if (attributeValue != null) {
+						return attributeValue;
+					}
+				}
+			}
+		}
+		
+		return attributeValue;
+	}
+	
+	@Override
+	@SuppressWarnings("unchecked")
+	public <T> @Nullable T getSpecificAttribute(final ConfigAttribute<T> configAttribute,
+			final DisplayMode displayMode, final @Nullable String configLabel) {
+		@Nullable T attributeValue= null;
+		
+		final Map<DisplayMode, Map<String, ?>> displayModeAttributeMap= this.configRegistry.get(configAttribute);
+		if (displayModeAttributeMap != null) {
+			final Map<String, T> configAttributeMap= (Map<String, T>)displayModeAttributeMap.get(displayMode);
+			if (configAttributeMap != null) {
+				attributeValue= configAttributeMap.get(configLabel);
+				if (attributeValue != null) {
+					return attributeValue;
+				}
+			}
+		}
+		
+		return attributeValue;
+	}
+	
+	@Override
+	public <T> void registerAttribute(final ConfigAttribute<T> configAttribute, final T attributeValue) {
+		registerAttribute(configAttribute, attributeValue, DisplayMode.NORMAL);
+	}
+	
+	@Override
+	public <T> void registerAttribute(final ConfigAttribute<T> configAttribute, final T attributeValue,
+			final DisplayMode displayMode) {
+		registerAttribute(configAttribute, attributeValue, displayMode, null);
+	}
+	
+	@Override
+	@SuppressWarnings("unchecked")
+	public <T> void registerAttribute(final ConfigAttribute<T> configAttribute, final T attributeValue,
+			final DisplayMode displayMode, final String configLabel) {
+		Map<DisplayMode, Map<String, ?>> displayModeAttributeMap= this.configRegistry.get(configAttribute);
+		if (displayModeAttributeMap == null) {
+			displayModeAttributeMap= new HashMap<>();
+			this.configRegistry.put(configAttribute, displayModeAttributeMap);
+		}
+		
+		Map<String, T> configAttributeMap= (Map<String, T>) displayModeAttributeMap.get(displayMode);
+		if (configAttributeMap == null) {
+			configAttributeMap= new HashMap<>();
+			displayModeAttributeMap.put(displayMode, configAttributeMap);
+		}
+		
+		configAttributeMap.put(configLabel, attributeValue);
+	}
+	
+	@Override
+	@SuppressWarnings("unchecked")
+	public <T> void unregisterAttribute(final ConfigAttribute<T> configAttributeType,
+			final DisplayMode displayMode, final String configLabel) {
+		final Map<DisplayMode, Map<String, ?>> displayModeAttributeMap= this.configRegistry.get(configAttributeType);
+		if (displayModeAttributeMap != null) {
+			final Map<String, T> configAttributeMap= (Map<String, T>) displayModeAttributeMap.get(displayMode);
+			if (configAttributeMap != null) {
+				configAttributeMap.remove(configLabel);
+			}
+		}
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/ConfigAttribute.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/ConfigAttribute.java
index f8b48be3..58f4166b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/ConfigAttribute.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/ConfigAttribute.java
@@ -11,9 +11,12 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.style;
+package org.eclipse.statet.ecommons.waltable.core.config;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+
+@NonNullByDefault
 public class ConfigAttribute<T> {
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IConfigRegistry.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/ConfigRegistry.java
index a9dbb5a2..697a09ac 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/config/IConfigRegistry.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/ConfigRegistry.java
@@ -11,35 +11,37 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.config;
+package org.eclipse.statet.ecommons.waltable.core.config;
 
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.IDisplayModeLookupStrategy;
+import org.eclipse.statet.jcommons.lang.NonNull;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
 
 /**
- * Holds all the settings, bindings and other configuration for NatTable.
- * <p>
- * See ConfigRegistryTest for a better understanding.
- * @see ConfigRegistry
+ * @see BasicConfigRegistry
  */
-public interface IConfigRegistry {
+@NonNullByDefault
+public interface ConfigRegistry {
+	
+	
+	DisplayModeLookupStrategy getDisplayModeOrdering();
+	
 	
 	/**
 	 * If retrieving registered values
 	 * <p>
 	 * Example 1:
-	 * 	 <p>configRegistry.getConfigAttribute(attribute, DisplayMode.EDIT);</p>
+	 * 	 <p>registry.getAttribute(attribute, DisplayMode.EDIT);</p>
 	 * <ol>
 	 * <li>It will look for an attribute registered using the EDIT display mode</li>
 	 * <li>If it can't find that it will try and find an attribute under the NORMAL mode</li>
-	 * <li>If it can't find one it will try and find one registered without a display mode {@link #registerConfigAttribute(ConfigAttribute, Object)}</li>
+	 * <li>If it can't find one it will try and find one registered without a display mode {@link #registerAttribute(ConfigAttribute, Object)}</li>
 	 * </ol>
 	 * Example 2:
-	 *   <p>configRegistry.getConfigAttribute(attribute, DisplayMode.NORMAL, "testLabel", "testLabel_1");</p>
+	 *   <p>registry.getAttribute(attribute, DisplayMode.NORMAL, "testLabel", "testLabel_1");</p>
 	 * <ol>
 	 * <li>It will look for an attribute registered by display mode NORMAL and "testLabel"</li>
 	 * <li>It will look for an attribute registered by display mode NORMAL and "testLabel_1"</li>
@@ -50,36 +52,38 @@ public interface IConfigRegistry {
 	 * @param configLabels the cell needs to have,  for this attribute to be returned
 	 * @return the configAttribute, if the display mode and the configLabels match
 	 */
-	<T> T getConfigAttribute(ConfigAttribute<T> configAttribute, DisplayMode targetDisplayMode, String...configLabels);
+	<T> @Nullable T getAttribute(ConfigAttribute<T> configAttribute, DisplayMode targetDisplayMode,
+			@NonNull String... configLabels);
 	
 	/**
-	 * @see #getConfigAttribute(ConfigAttribute, DisplayMode, String...)
+	 * @see #getAttribute(ConfigAttribute, DisplayMode, String...)
 	 */
-	<T> T getConfigAttribute(ConfigAttribute<T> configAttribute, DisplayMode targetDisplayMode, List<String> configLabels);
+	<T> @Nullable T getAttribute(ConfigAttribute<T> configAttribute, DisplayMode targetDisplayMode,
+			List<String> configLabels);
 	
 	/**
-	 * @see #getConfigAttribute(ConfigAttribute, DisplayMode, String...)
+	 * @see #getAttribute(ConfigAttribute, DisplayMode, String...)
 	 */
-	<T> T getSpecificConfigAttribute(ConfigAttribute<T> configAttribute, DisplayMode displayMode, String configLabel);
+	<T> @Nullable T getSpecificAttribute(ConfigAttribute<T> configAttribute, DisplayMode displayMode,
+			@Nullable String configLabel);
 	
 	
 	/**
 	 * Register a configuration attribute
 	 */
-	<T> void registerConfigAttribute(ConfigAttribute<T> configAttribute, T attributeValue);
+	<T> void registerAttribute(ConfigAttribute<T> configAttribute, T attributeValue);
 	
 	/**
 	 * Register an attribute against a {@link DisplayMode}.
 	 */
-	<T> void registerConfigAttribute(ConfigAttribute<T> configAttribute, T attributeValue, DisplayMode targetDisplayMode);
+	<T> void registerAttribute(ConfigAttribute<T> configAttribute, T attributeValue, DisplayMode targetDisplayMode);
 	
 	/**
 	 * Register an attribute against a {@link DisplayMode} and configuration label (applied to cells)
 	 */
-	<T> void registerConfigAttribute(ConfigAttribute<T> configAttribute, T attributeValue, DisplayMode targetDisplayMode, String configLabel);
+	<T> void registerAttribute(ConfigAttribute<T> configAttribute, T attributeValue, DisplayMode targetDisplayMode, String configLabel);
 	
-	<T> void unregisterConfigAttribute(ConfigAttribute<T> configAttributeType, DisplayMode displayMode, String configLabel);
+	<T> void unregisterAttribute(ConfigAttribute<T> configAttributeType, DisplayMode displayMode, String configLabel);
 	
-	IDisplayModeLookupStrategy getDisplayModeOrdering();
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/DefaultDisplayModeOrdering.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/DefaultDisplayModeOrdering.java
new file mode 100644
index 00000000..44f6ca57
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/DefaultDisplayModeOrdering.java
@@ -0,0 +1,52 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.config;
+
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+
+@NonNullByDefault
+public class DefaultDisplayModeOrdering implements DisplayModeLookupStrategy {
+	
+	
+	private static final ImList<DisplayMode> NORMAL_ORDERING= ImCollections.newList(DisplayMode.NORMAL);
+	
+	private static final ImList<DisplayMode> HOVER_ORDERING= ImCollections.newList(DisplayMode.HOVER, DisplayMode.NORMAL);
+	
+	private static final ImList<DisplayMode> SELECT_ORDERING= ImCollections.newList(DisplayMode.SELECTED, DisplayMode.NORMAL);
+	
+	private static final ImList<DisplayMode> EDIT_ORDERING= ImCollections.newList(DisplayMode.EDIT, DisplayMode.NORMAL);
+	
+	private static final ImList<DisplayMode> EMPTY_ORDERING= ImCollections.emptyList();
+	
+	
+	@Override
+	public ImList<DisplayMode> getDisplayModeOrdering(final DisplayMode targetDisplayMode) {
+		switch (targetDisplayMode) {
+		case NORMAL:
+			return NORMAL_ORDERING;
+		case HOVER:
+			return HOVER_ORDERING;
+		case SELECTED:
+			return SELECT_ORDERING;
+		case EDIT:
+			return EDIT_ORDERING;
+		default:
+			return EMPTY_ORDERING;
+		}
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/DisplayMode.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/DisplayMode.java
index 7b60a48e..56e2cc42 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/DisplayMode.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/DisplayMode.java
@@ -11,7 +11,9 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.style;
+package org.eclipse.statet.ecommons.waltable.core.config;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 
 /**
@@ -19,19 +21,19 @@ package org.eclipse.statet.ecommons.waltable.style;
  * <ol>
  *    <li>During normal display a cell is in NORMAL mode.</li>
  *    <li>If the contents of the cell are being edited, its in EDIT mode.</li>
- *    <li>If a cell has been selected, its in SELECT mode.</li>
+ *    <li>If a cell has been selected, its in SELECTED mode.</li>
  * </ol>
  * 
- * These modes are used to bind different settings to different modes.
- * For example, a different style can be registered for a cell
- * when it is in SELECT mode.
- * 
+ * These modes are used to bind different settings to different modes. For
+ * example, a different style can be registered for a cell when it is in
+ * SELECTED mode.
  */
+@NonNullByDefault
 public enum DisplayMode {
 	
 	NORMAL,
 	HOVER,
-	SELECT,
+	SELECTED,
 	EDIT;
 	
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/IDisplayModeLookupStrategy.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/DisplayModeLookupStrategy.java
index 702d20da..4c81cad8 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/IDisplayModeLookupStrategy.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/config/DisplayModeLookupStrategy.java
@@ -11,14 +11,16 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.style;
+package org.eclipse.statet.ecommons.waltable.core.config;
 
-import java.util.List;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 
-public interface IDisplayModeLookupStrategy {
+@NonNullByDefault
+public interface DisplayModeLookupStrategy {
 	
 	
-	List<DisplayMode> getDisplayModeOrdering(DisplayMode targetDisplayMode);
+	ImList<DisplayMode> getDisplayModeOrdering(DisplayMode targetDisplayMode);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/Direction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/Direction.java
new file mode 100644
index 00000000..7884e988
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/Direction.java
@@ -0,0 +1,154 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.coordinate;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+
+@NonNullByDefault
+public enum Direction {
+	
+	
+	LEFT {
+		
+		@Override
+		public Orientation getOrientation() {
+			return HORIZONTAL;
+		}
+		
+		@Override
+		public boolean isForward() {
+			return false;
+		}
+		
+		@Override
+		public boolean isBackward() {
+			return true;
+		}
+		
+		@Override
+		public Direction getOpposite() {
+			return RIGHT;
+		}
+		
+	},
+	
+	RIGHT {
+		
+		@Override
+		public Orientation getOrientation() {
+			return HORIZONTAL;
+		}
+		
+		@Override
+		public boolean isForward() {
+			return true;
+		}
+		
+		@Override
+		public boolean isBackward() {
+			return false;
+		}
+		
+		@Override
+		public Direction getOpposite() {
+			return LEFT;
+		}
+		
+	},
+	
+	UP {
+		
+		@Override
+		public Orientation getOrientation() {
+			return VERTICAL;
+		}
+		
+		@Override
+		public boolean isForward() {
+			return false;
+		}
+		
+		@Override
+		public boolean isBackward() {
+			return true;
+		}
+		
+		@Override
+		public Direction getOpposite() {
+			return DOWN;
+		}
+		
+	},
+	
+	DOWN {
+		
+		@Override
+		public Orientation getOrientation() {
+			return VERTICAL;
+		}
+		
+		@Override
+		public boolean isForward() {
+			return true;
+		}
+		
+		@Override
+		public boolean isBackward() {
+			return false;
+		}
+		
+		@Override
+		public Direction getOpposite() {
+			return UP;
+		}
+		
+	};
+	
+	
+	public static Direction forward(final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return RIGHT;
+		case VERTICAL:
+			return LEFT;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	public static Direction backward(final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return LEFT;
+		case VERTICAL:
+			return UP;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	
+	public abstract Orientation getOrientation();
+	
+	public abstract boolean isForward();
+	
+	public abstract boolean isBackward();
+	
+	public abstract Direction getOpposite();
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/LPoint.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/LPoint.java
index ac9cbe7e..154a8291 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/LPoint.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/LPoint.java
@@ -12,25 +12,27 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.coordinate;
+package org.eclipse.statet.ecommons.waltable.core.coordinate;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+
+import org.eclipse.statet.jcommons.lang.Immutable;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
 
 /**
- * Instances of this class represent places on the (x, y)
- * coordinate plane.
+ * Point on the (x, y) coordinate plane.
  * 
- * <p>The coordinate space for rectangles and points is considered
- * to have increasing values downward and to the right from its
- * origin making this the normal, computer graphics oriented notion
- * of (x, y) coordinates rather than the strict mathematical one.
- * </p>
+ * <p>The coordinate space for rectangles and points is considered to have
+ * increasing values downward and to the right from its origin making this
+ * the normal, computer graphics oriented notion of (x, y) coordinates rather
+ * than the strict mathematical one.</p>
  * 
  * @see LRectangle
  */
-
-public final class LPoint {
+@NonNullByDefault
+public final class LPoint implements Immutable {
 	
 	/**
 	 * the x coordinate of the point
@@ -49,7 +51,7 @@ public final class LPoint {
 	 * @param x the x coordinate
 	 * @param y the y coordinate
 	 */
-	public LPoint (final long x, final long y) {
+	public LPoint(final long x, final long y) {
 		this.x= x;
 		this.y= y;
 	}
@@ -64,19 +66,19 @@ public final class LPoint {
 	
 	@Override
 	public int hashCode() {
-		int h= (int) (this.x ^ (this.x >>> 32));
+		int h= (int)(this.x ^ (this.x >>> 32));
 		h= Integer.rotateRight(h, 15);
-		h ^= (int) (this.y ^ (this.y >>> 32));
+		h ^= (int)(this.y ^ (this.y >>> 32));
 		return h ^ (h >>> 7);
 	}
 	
 	@Override
-	public boolean equals(final Object obj) {
+	public boolean equals(final @Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}
 		if (obj instanceof LPoint) {
-			final LPoint other= (LPoint) obj;
+			final LPoint other= (LPoint)obj;
 			return (this.x == other.x && this.y == other.y);
 		}
 		return false;
@@ -84,8 +86,8 @@ public final class LPoint {
 	
 	
 	@Override
-	public String toString () {
-		return "LPoint {" + this.x + ", " + this.y + "}"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+	public String toString() {
+		return "{" + this.x + ", " + this.y + "}L"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/LRange.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/LRange.java
index 9a19ef9b..3435d16f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/LRange.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/LRange.java
@@ -11,17 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.coordinate;
+package org.eclipse.statet.ecommons.waltable.core.coordinate;
 
-import java.util.ArrayList;
-import java.util.List;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
 
 /**
- * Represents an LRange of numbers.
- * Example a LRange of selected rows: 1 - 100
- * Ranges are inclusive of their start value and not inclusive of their end value, i.e. start &lt;= x &lt; end
+ * Range of numbers of type long.
+ * 
+ * <p>Ranges are inclusive of their start value and exclusive of their end value,
+ * start &lt;= x &lt; end.</p>
  */
+@NonNullByDefault
 public final class LRange implements Comparable<LRange> {
 	
 	
@@ -52,17 +54,17 @@ public final class LRange implements Comparable<LRange> {
 	
 	
 	@Override
-	public int compareTo(final LRange o) {
-		if (this.start < o.start) {
+	public int compareTo(final LRange other) {
+		if (this.start < other.start) {
 			return -1;
 		}
-		if (this.start > o.start) {
+		if (this.start > other.start) {
 			return 1;
 		}
-		if (this.end < o.end) {
+		if (this.end < other.end) {
 			return -1;
 		}
-		if (this.end > o.end) {
+		if (this.end > other.end) {
 			return 1;
 		}
 		return 0;
@@ -72,51 +74,40 @@ public final class LRange implements Comparable<LRange> {
 	 * @return <code>true</code> if the range contains the given row position
 	 */
 	public boolean contains(final long position) {
-		return ((position >= this.start) && (position < this.end));
+		return (position >= this.start && position < this.end);
 	}
-
+	
 	public boolean overlap(final LRange lRange) {
-		return ((this.start < this.end) &&  // this is a non-empty range
-				(lRange.start < lRange.end) &&  // range parameter is non-empty
-				(contains(lRange.start) || contains(lRange.end - 1) || lRange.contains(this.start) || lRange.contains(this.end - 1)) );
-	}
-
-	public List<Long> getMembers() {
-		final long l= size();
-		if (l > Integer.MAX_VALUE) {
-			throw new RuntimeException("too long: " + l);
-		}
-		final List<Long> members= new ArrayList<>((int) l);
-		for (long i= this.start; i < this.end; i++) {
-			members.add(Long.valueOf(i));
-		}
-		return members;
+		return (this.start < this.end &&  // this is non-empty
+				lRange.start < lRange.end &&  // parameter is non-empty
+				(contains(lRange.start) || contains(lRange.end - 1)
+						|| lRange.contains(this.start) || lRange.contains(this.end - 1) ));
 	}
-
-
+	
+	
 	@Override
 	public int hashCode() {
-		int h= (int) (this.start ^ (this.start >>> 32));
+		int h= (int)(this.start ^ (this.start >>> 32));
 		h= Integer.rotateRight(h, 15);
-		h ^= (int) (this.end ^ (this.end >>> 32));
+		h ^= (int)(this.end ^ (this.end >>> 32));
 		return h ^ (h >>> 7);
 	}
-
+	
 	@Override
-	public boolean equals(final Object obj) {
+	public boolean equals(final @Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}
-		if (!(obj instanceof LRange)) {
-			return false;
+		if (obj instanceof LRange) {
+			final LRange other= (LRange)obj;
+			return (this.start == other.start && this.end == other.end);
 		}
-		final LRange other= (LRange) obj;
-		return ((this.start == other.start) && (this.end == other.end));
+		return false;
 	}
 	
 	@Override
 	public String toString() {
-		return "LRange {" + this.start + ", " + this.end + "}"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+		return "[" + this.start + ", " + this.end + ")L"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/LRangeList.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/LRangeList.java
index 3f95d180..f630343d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/LRangeList.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/LRangeList.java
@@ -12,7 +12,7 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.coordinate;
+package org.eclipse.statet.ecommons.waltable.core.coordinate;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -20,19 +20,26 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
 
+import org.eclipse.statet.jcommons.collections.LongIterator;
+import org.eclipse.statet.jcommons.lang.NonNull;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
 
 /**
- * A special list for {@link LRange ranges}, which sorts and merges automatically all added ranges.
+ * A special list for {@link LRange ranges}, which sorts and merges
+ * automatically all added ranges.
  * <p>
- * Important Note: Added range objects may be changed if the list is modified. The range objects 
+ * Important Note: Added range objects may be changed if the list is modified. The range objects
  * must not be changed outside of the list.</p>
- * <p>
- * The add and remove methods of LRangeList guarantees that the ranges in a list object are never 
- * empty, do not intersect and touch and are always sorted.</p>
- * <p>
- * The class provides additionally direct {@link #values() access} to the single values described by
- * the ranges. 
+ * 
+ * <p>The add and remove methods of LRangeList guarantees that the ranges in a
+ * list object are never empty, do not intersect and touch and are always
+ * sorted.</p>
+ * <p>The class provides additionally direct {@link #values() access} to the
+ * single values described by the ranges.</p>
  */
+@NonNullByDefault
 public final class LRangeList extends ArrayList<LRange> implements Set<LRange> {
 	
 	
@@ -42,9 +49,9 @@ public final class LRangeList extends ArrayList<LRange> implements Set<LRange> {
 	/**
 	 * Iterator which allows to iterate over the values of a collection with {@link LRange} elements.
 	 * 
-	 * @see LRangeList#valuesIterator()
+	 * @see LRangeList#values()
 	 */
-	public static final class ValueIterator implements ILValueIterator {
+	public static final class ValueIterator implements LongIterator {
 		
 		
 		private final Iterator<LRange> rangeIter;
@@ -58,7 +65,7 @@ public final class LRangeList extends ArrayList<LRange> implements Set<LRange> {
 		 * 
 		 * @param c the collection to iterate over
 		 */
-		public ValueIterator(/*@NonNull*/ final Collection<LRange> c) {
+		public ValueIterator(final Collection<LRange> c) {
 			this.rangeIter= c.iterator();
 		}
 		
@@ -125,7 +132,7 @@ public final class LRangeList extends ArrayList<LRange> implements Set<LRange> {
 	 * 
 	 * @param initialRanges the ranges initially added to the list
 	 */
-	public LRangeList(final LRange... initialRanges) {
+	public LRangeList(final @NonNull LRange... initialRanges) {
 		this();
 		
 		for (int i= 0; i < initialRanges.length; i++) {
@@ -282,7 +289,7 @@ public final class LRangeList extends ArrayList<LRange> implements Set<LRange> {
 	}
 	
 	@Override
-	public boolean remove(final Object o) {
+	public boolean remove(final @Nullable Object o) {
 		if (o instanceof LRange) {
 			return remove((LRange) o);
 		}
@@ -359,7 +366,7 @@ public final class LRangeList extends ArrayList<LRange> implements Set<LRange> {
 		}
 		
 		@Override
-		public ILValueIterator iterator() {
+		public LongIterator iterator() {
 			return new ValueIterator(LRangeList.this);
 		}
 		
@@ -431,7 +438,7 @@ public final class LRangeList extends ArrayList<LRange> implements Set<LRange> {
 			return LRangeList.super.get(LRangeList.super.size() - 1).end - 1;
 		}
 		
-		public LRange getRangeOf(final long value) {
+		public @Nullable LRange getRangeOf(final long value) {
 			int idx= indexOfStart(value);
 			if (idx >= 0) { // value == range1.start
 				return LRangeList.super.get(idx);
@@ -457,10 +464,10 @@ public final class LRangeList extends ArrayList<LRange> implements Set<LRange> {
 		}
 		
 		@Override
-		public boolean equals(final Object obj) {
+		public boolean equals(final @Nullable Object obj) {
 			return ((this == obj
 					|| (obj instanceof Values 
-							&& LRangeList.this.equals(((Values) obj).getRangeList())) ));
+							&& LRangeList.this.equals(((Values)obj).getRangeList())) ));
 		}
 		
 	}
@@ -474,22 +481,4 @@ public final class LRangeList extends ArrayList<LRange> implements Set<LRange> {
 		return this.values;
 	}
 	
-	
-	@Deprecated // not recommend
-	public static Collection<Long> listValues(final Collection<LRange> positions) {
-		final ArrayList<Long> list= new ArrayList<>();
-		for (final Iterator<LRange> iter= positions.iterator(); iter.hasNext(); ) {
-			final LRange lRange= iter.next();
-			final long sum= list.size() + lRange.size();
-			if (sum > 0xffffff) {
-				throw new IndexOutOfBoundsException("" + sum); //$NON-NLS-1$ // TODO implement ranges
-			}
-			list.ensureCapacity((int) sum);
-			for (long position= lRange.start; position < lRange.end; position++) {
-				list.add(position);
-			}
-		}
-		return list;
-	}
-	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/LRectangle.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/LRectangle.java
index f62c2345..b1a7edbe 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/LRectangle.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/LRectangle.java
@@ -12,26 +12,27 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation for long coordinates
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.coordinate;
+package org.eclipse.statet.ecommons.waltable.core.coordinate;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
 
 /**
  * Instances of this class represent rectangular areas in an (x, y) coordinate system. The top left
  * corner of the rectangle is specified by its x and y values, and the extent of the rectangle is 
  * specified by its width and height.
- * <p>
- * The coordinate space for rectangles and points is considered to have increasing values downward
+ * 
+ * <p>The coordinate space for rectangles and points is considered to have increasing values downward
  * and to the right from its origin making this the normal, computer graphics oriented notion
  * of (x, y) coordinates rather than the strict mathematical one.
  * </p>
- * <p>
- * The hashCode() method in this class uses the values of the public fields to compute the hash 
+ * <p>The hashCode() method in this class uses the values of the public fields to compute the hash 
  * value. When storing instances of the class in hashed collections, do not modify these fields 
  * after the object has been inserted.
  * </p>
  */
+@NonNullByDefault
 public final class LRectangle {
 	
 	/**
@@ -97,7 +98,7 @@ public final class LRectangle {
 	 * @return <code>true</code> if the receiver is empty, and <code>false</code> otherwise
 	 */
 	public boolean isEmpty() {
-		return ((this.width <= 0) || (this.height <= 0));
+		return (this.width <= 0 || this.height <= 0);
 	}
 	
 	/**
@@ -109,8 +110,8 @@ public final class LRectangle {
 	 * @return <code>true</code> if the rectangle contains the point and <code>false</code> otherwise
 	 */
 	public boolean contains(final long x, final long y) {
-		return ((x >= this.x) && (y >= this.y)
-				&& x < (this.x + this.width) && y < (this.y + this.height) );
+		return (x >= this.x && y >= this.y
+				&& x < this.x + this.width && y < this.y + this.height );
 	}
 	
 	/**
@@ -123,7 +124,7 @@ public final class LRectangle {
 	 * 
 	 * @exception NullPointerException if the argument is <code>null</code>
 	 */
-	public boolean contains(/*@NonNull*/ final LPoint pt) {
+	public boolean contains(final LPoint pt) {
 		if (pt == null) {
 			throw new NullPointerException("pt"); //$NON-NLS-1$
 		}
@@ -141,7 +142,7 @@ public final class LRectangle {
 	 * 
 	 * @exception NullPointerException if the argument is <code>null</code>
 	 */
-	public boolean contains(/*@NonNull*/ final LRectangle rect) {
+	public boolean contains(final LRectangle rect) {
 		if (rect == null) {
 			throw new NullPointerException("rect"); //$NON-NLS-1$
 		}
@@ -189,7 +190,7 @@ public final class LRectangle {
 	 * @see #intersection(LRectangle)
 	 * @see #isEmpty()
 	 */
-	public boolean intersects(/*@NonNull*/ final LRectangle rect) {
+	public boolean intersects(final LRectangle rect) {
 		if (rect == null) {
 			throw new NullPointerException("rect"); //$NON-NLS-1$
 		}
@@ -197,69 +198,6 @@ public final class LRectangle {
 	}
 	
 	
-	//-- Destructive Methods --//
-	
-	/**
-	 * Destructively replaces the x, y, width and height values in the receiver with ones which 
-	 * represent the union of the rectangles specified by the receiver and the given rectangle.
-	 * <p>
-	 * The union of two rectangles is the smallest single rectangle that completely covers both of
-	 * the areas covered by the two given rectangles.
-	 * </p>
-	 * 
-	 * @param rect the rectangle to merge with the receiver
-	 * 
-	 * @exception NullPointerException if the argument is <code>null</code>
-	 */
-	public void add(/*@NonNull*/ final LRectangle rect) {
-		if (rect == null) {
-			throw new NullPointerException("rect"); //$NON-NLS-1$
-		}
-		final long left= (this.x < rect.x) ? this.x : rect.x;
-		final long top= (this.y < rect.y) ? this.y : rect.y;
-		long lhs= this.x + this.width;
-		long rhs= rect.x + rect.width;
-		final long right= (lhs > rhs) ? lhs : rhs;
-		lhs= this.y + this.height;
-		rhs= rect.y + rect.height;
-		final long bottom= (lhs > rhs) ? lhs : rhs;
-		this.x= left;
-		this.y= top;
-		this.width= right - left;
-		this.height= bottom - top;
-	}
-	
-	/**
-	 * Destructively replaces the x, y, width and height values in the receiver with ones which 
-	 * represent the intersection of the rectangles specified by the receiver and the given
-	 * rectangle.
-	 * 
-	 * @param rect the rectangle to intersect with the receiver
-	 * 
-	 * @exception NullPointerException if the argument is <code>null</code>
-	 */
-	public void intersect(/*@NonNull*/ final LRectangle rect) {
-		if (rect == null) {
-			throw new NullPointerException("rect"); //$NON-NLS-1$
-		}
-		if (this == rect) {
-			return;
-		}
-		final long left= (this.x > rect.x) ? this.x : rect.x;
-		final long top= (this.y > rect.y) ? this.y : rect.y;
-		long lhs= this.x + this.width;
-		long rhs= rect.x + rect.width;
-		final long right= (lhs < rhs) ? lhs : rhs;
-		lhs= this.y + this.height;
-		rhs= rect.y + rect.height;
-		final long bottom= (lhs < rhs) ? lhs : rhs;
-		this.x= (right < left) ? 0 : left;
-		this.y= (bottom < top) ? 0 : top;
-		this.width= (right < left) ? 0 : right - left;
-		this.height= (bottom < top) ? 0 : bottom - top;
-	}
-	
-	
 	//-- Methods Creating New Coordinate Objects --//
 	
 	/**
@@ -275,7 +213,7 @@ public final class LRectangle {
 	 * 
 	 * @exception NullPointerException if the argument is <code>null</code>
 	 */
-	public LRectangle intersection(/*@NonNull*/ final LRectangle rect) {
+	public LRectangle intersection(final LRectangle rect) {
 		if (rect == null) {
 			throw new NullPointerException("rect"); //$NON-NLS-1$
 		}
@@ -311,7 +249,7 @@ public final class LRectangle {
 	 * 
 	 * @see #add(LRectangle)
 	 */
-	public LRectangle union(/*@NonNull*/ final LRectangle rect) {
+	public LRectangle union(final LRectangle rect) {
 		if (rect == null) {
 			throw new NullPointerException("rect"); //$NON-NLS-1$
 		}
@@ -332,13 +270,26 @@ public final class LRectangle {
 	 * @param orientation the orientation
 	 * @return the range of the rectangle
 	 */
-	public LRange getRange(/*@NonNull*/ final Orientation orientation) {
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
+	public LRange getRange(final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return new LRange(this.x, this.x + this.width);
+		case VERTICAL:
+			return new LRange(this.y, this.y + this.height);
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	public long getSize(final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return this.width;
+		case VERTICAL:
+			return this.height;
+		default:
+			throw new IllegalStateException();
 		}
-		return (orientation == HORIZONTAL) ?
-				new LRange(this.x, this.x + this.width) :
-				new LRange(this.y, this.y + this.height);
 	}
 	
 	public LRectangle switchOrientation() {
@@ -348,52 +299,29 @@ public final class LRectangle {
 	
 	//-- Object Methods --//
 	
-	/**
-	 * Returns an integer hash code for the receiver. Any two objects that return <code>true</code>
-	 * when passed to <code>equals</code> must return the same value for this method.
-	 * 
-	 * @return the receiver's hash
-	 * 
-	 * @see #equals(Object)
-	 */
 	@Override
 	public int hashCode() {
-		int h= (int) (this.x ^ (this.x >>> 32));
-		h ^= Integer.rotateLeft((int) (this.width ^ (this.width >>> 32)), 3);
+		int h= (int)(this.x ^ (this.x >>> 32));
+		h ^= Integer.rotateLeft((int)(this.width ^ (this.width >>> 32)), 3);
 		h= Integer.rotateRight(h, 15);
 		h ^= (int) (this.y ^ (this.y >>> 32));
-		h ^= Integer.rotateLeft((int) (this.height ^ (this.height >>> 32)), 3);
+		h ^= Integer.rotateLeft((int)(this.height ^ (this.height >>> 32)), 3);
 		return h ^ (h >>> 7);
 	}
 	
-	/**
-	 * Compares the argument to the receiver, and returns true if they represent the <em>same</em>
-	 * object using a class specific comparison.
-	 * 
-	 * @param object the object to compare with this object
-	 * @return <code>true</code> if the object is the same as this object and <code>false</code>
-	 *     otherwise
-	 * 
-	 * @see #hashCode()
-	 */
 	@Override
-	public boolean equals(final Object object) {
+	public boolean equals(final @Nullable Object object) {
 		if (object == this) {
 			return true;
 		}
-		if (!(object instanceof LRectangle)) {
-			return false;
+		if (object instanceof LRectangle) {
+			final LRectangle other= (LRectangle)object;
+			return (this.x == other.x && this.y == other.y
+					&& this.width == other.width && this.height == other.height );
 		}
-		final LRectangle other= (LRectangle) object;
-		return ((this.x == other.x) && (this.y == other.y)
-				&& (this.width == other.width) && (this.height == other.height) );
+		return false;
 	}
 	
-	/**
-	 * Returns a string containing a concise, human-readable description of the receiver.
-	 * 
-	 * @return a string representation of the rectangle
-	 */
 	@Override
 	public String toString() {
 		return "LRectangle {" + this.x + ", " + this.y + ", " + this.width + ", " + this.height + "}"; //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/Orientation.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/Orientation.java
index 45a3b9e4..a8bc8674 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/Orientation.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/Orientation.java
@@ -12,25 +12,40 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.coordinate;
+package org.eclipse.statet.ecommons.waltable.core.coordinate;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+
+@NonNullByDefault
 public enum Orientation {
 	
 	
 	/**
 	 * The horizontal orientation (columns)
 	 */
-	HORIZONTAL,
+	HORIZONTAL {
+		
+		@Override
+		public Orientation getOrthogonal() {
+			return VERTICAL;
+		}
+		
+	},
 	
 	/**
 	 * The vertical orientation (rows)
 	 */
-	VERTICAL();
+	VERTICAL {
+		
+		@Override
+		public Orientation getOrthogonal() {
+			return HORIZONTAL;
+		}
+		
+	};
 	
 	
-	public Orientation getOrthogonal() {
-		return (this == HORIZONTAL) ? VERTICAL : HORIZONTAL;
-	}
+	public abstract Orientation getOrthogonal();
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/PixelOutOfBoundsException.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/PixelOutOfBoundsException.java
new file mode 100644
index 00000000..fb32e23a
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/PixelOutOfBoundsException.java
@@ -0,0 +1,31 @@
+/*=============================================================================#
+ # Copyright (c) 2013, 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.coordinate;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+
+@NonNullByDefault
+public class PixelOutOfBoundsException extends IllegalArgumentException {
+	
+	
+	private static final long serialVersionUID= 1L;
+	
+	
+	public PixelOutOfBoundsException(final long pixel, final Orientation orientation) {
+		super("pixel (" + orientation + ")= " + pixel); //$NON-NLS-1$ //$NON-NLS-2$
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PositionId.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/PositionId.java
index 1f31dde3..70a61b97 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PositionId.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/PositionId.java
@@ -12,9 +12,12 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.coordinate;
+package org.eclipse.statet.ecommons.waltable.core.coordinate;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+
+@NonNullByDefault
 public class PositionId {
 	
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PositionOutOfBoundsException.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/PositionOutOfBoundsException.java
index 7357200a..02479833 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/PositionOutOfBoundsException.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/coordinate/PositionOutOfBoundsException.java
@@ -12,28 +12,18 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.coordinate;
+package org.eclipse.statet.ecommons.waltable.core.coordinate;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+
+@NonNullByDefault
 public class PositionOutOfBoundsException extends IllegalArgumentException {
 	
 	
 	private static final long serialVersionUID= 1L;
 	
 	
-	public static PositionOutOfBoundsException position(final long position,
-			final Orientation orientation) {
-		return new PositionOutOfBoundsException("position", position, orientation); //$NON-NLS-1$
-	}
-	
-	public static PositionOutOfBoundsException position(final long position) {
-		return new PositionOutOfBoundsException("position", position); //$NON-NLS-1$
-	}
-	
-	public static PositionOutOfBoundsException underlyingPosition(final long position) {
-		return new PositionOutOfBoundsException("underlyingPosition", position); //$NON-NLS-1$
-	}
-	
 	public static PositionOutOfBoundsException refPosition(final long position,
 			final Orientation orientation) {
 		return new PositionOutOfBoundsException("refPosition", position, orientation); //$NON-NLS-1$
@@ -53,4 +43,12 @@ public class PositionOutOfBoundsException extends IllegalArgumentException {
 		super(label + " (" + orientation + "): " + position); //$NON-NLS-1$ //$NON-NLS-2$
 	}
 	
+	public PositionOutOfBoundsException(final long position) {
+		super("position= " + position); //$NON-NLS-1$
+	}
+	
+	public PositionOutOfBoundsException(final long position, final Orientation orientation) {
+		super("position (" + orientation + ")= " + position); //$NON-NLS-1$ //$NON-NLS-2$
+	}
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IColumnAccessor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/ColumnAccessor.java
index 876cec35..34cf9f3f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IColumnAccessor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/ColumnAccessor.java
@@ -11,20 +11,27 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.data;
+package org.eclipse.statet.ecommons.waltable.core.data;
+
+import org.eclipse.statet.jcommons.lang.NonNull;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
 
 /**
- * Maps the properties from the row object to the corresponding columns. 
+ * Maps the properties from the row object to the corresponding columns.
+ *  
  * @param <T> type of the bean used as a row object
  */
-public interface IColumnAccessor<T> {
+@NonNullByDefault
+public interface ColumnAccessor<T> {
+	
 	
+	long getColumnCount();
 	
-	Object getDataValue(T rowObject, long columnIndex);
 	
-	void setDataValue(T rowObject, long columnIndex, Object newValue);
+	@Nullable Object getDataValue(@NonNull T rowObject, long columnIndex);
 	
-	long getColumnCount();
+	void setDataValue(@NonNull T rowObject, long columnIndex, @Nullable Object newValue);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ControlData.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/ControlData.java
index 4f722f2a..48928e60 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ControlData.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/ControlData.java
@@ -12,9 +12,13 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.data;
+package org.eclipse.statet.ecommons.waltable.core.data;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+
+@NonNullByDefault
 public class ControlData {
 	
 	
@@ -50,7 +54,7 @@ public class ControlData {
 	}
 	
 	@Override
-	public boolean equals(final Object obj) {
+	public boolean equals(final @Nullable Object obj) {
 		return (obj == this
 				|| (obj instanceof ControlData
 						&& this.code == ((ControlData) obj).code ));
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/DataCell.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/DataCell.java
index 279719a6..aa1f9b59 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/DataCell.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/DataCell.java
@@ -11,9 +11,13 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer.cell;
+package org.eclipse.statet.ecommons.waltable.core.data;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+
+@NonNullByDefault
 public class DataCell {
 
 	protected long columnPosition;
@@ -68,18 +72,18 @@ public class DataCell {
 	}
 	
 	@Override
-	public boolean equals(final Object obj) {
+	public boolean equals(final @Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}
-		if (!(obj instanceof DataCell)) {
-			return false;
+		if (obj instanceof DataCell) {
+			final DataCell other= (DataCell) obj;
+			return (this.columnPosition == other.columnPosition
+					&& this.rowPosition == other.rowPosition
+					&& this.columnSpan == other.columnSpan
+					&& this.rowSpan == other.rowSpan);
 		}
-		final DataCell other= (DataCell) obj;
-		return (this.columnPosition == other.columnPosition
-				&& this.rowPosition == other.rowPosition
-				&& this.columnSpan == other.columnSpan
-				&& this.rowSpan == other.rowSpan);
+		return false;
 	}
 	
 	@Override
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/DataProvider.java
index bca56e4c..4267e0f0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/DataProvider.java
@@ -11,20 +11,22 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.data;
+package org.eclipse.statet.ecommons.waltable.core.data;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
 
 /**
  * Provide data to the table.
  * 
- * @see DataLayer
  * @see ListDataProvider
+ * @see org.eclipse.statet.ecommons.waltable.data.core.DataLayer
  */
-public interface IDataProvider {
+@NonNullByDefault
+public interface DataProvider {
 	
 	
 	int FORCE_SYNC= 1 << 0;
@@ -44,17 +46,18 @@ public interface IDataProvider {
 	 * @param monitor
 	 * @return the data value associated with the specified cell
 	 */
-	Object getDataValue(long columnIndex, long rowIndex,
-			int flags, IProgressMonitor monitor);
+	@Nullable Object getDataValue(long columnIndex, long rowIndex,
+			int flags, @Nullable IProgressMonitor monitor);
 	
 	/**
-	 * Sets the value at the given column and row index. Optional operation. Should throw UnsupportedOperationException
-	 * if this operation is not supported.
+	 * Sets the value at the given column and row index. Optional operation.
+	 * 
+	 * The method throws an UnsupportedOperationException if this operation is not supported.
 	 *
 	 * @param columnIndex
 	 * @param rowIndex
 	 * @param newValue
 	 */
-	void setDataValue(long columnIndex, long rowIndex, Object newValue);
+	void setDataValue(long columnIndex, long rowIndex, @Nullable Object newValue);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ListDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/ListDataProvider.java
index 55875704..cc772c20 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ListDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/ListDataProvider.java
@@ -11,35 +11,47 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.data;
+package org.eclipse.statet.ecommons.waltable.core.data;
 
 import java.util.List;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
 
 /**
- * Enables the use of a {@link List} containing POJO(s) as a backing data source.
+ * Enables the use of a {@link List} containing POJO(s) as a backing data
+ * source.
+ * 
+ * <p>By default a bean at position {@code x} in the list is displayed in row
+ * {@code x} in the table. A {@link ColumnAccessor} is used to retrieve column
+ * data from the row objects.</p>
  * 
- * By default a bean at position 'X' in the list is displayed in 
- * row 'X' in the table. The properties of the bean are used to 
- * populate the columns. A {@link IColumnPropertyResolver} is used to
- * retrieve column data from the bean properties. 
+ * @param <T> type of the row objects in the backing list.
  * 
- * @param <T> type of the Objects in the backing list.
- * @see IColumnPropertyResolver
+ * @see org.eclipse.statet.ecommons.waltable.util.data.PropertyColumnResolver
  */
-public class ListDataProvider<T> implements IRowDataProvider<T> {
+@NonNullByDefault
+public class ListDataProvider<T> implements DataProvider {
 	
-	protected List<T> list;
-	protected IColumnAccessor<T> columnAccessor;
 	
+	protected final List<T> list;
+	protected final ColumnAccessor<T> columnAccessor;
 	
-	public ListDataProvider(final List<T> list, final IColumnAccessor<T> columnAccessor) {
+	
+	public ListDataProvider(final List<T> list, final ColumnAccessor<T> columnAccessor) {
 		this.list= list;
 		this.columnAccessor= columnAccessor;
 	}
 	
+	
+	public List<T> getList() {
+		return this.list;
+	}
+	
+	
 	@Override
 	public long getColumnCount() {
 		return this.columnAccessor.getColumnCount();
@@ -50,25 +62,6 @@ public class ListDataProvider<T> implements IRowDataProvider<T> {
 		return this.list.size();
 	}
 	
-	@Override
-	public Object getDataValue(final long columnIndex, final long rowIndex, final int flags, final IProgressMonitor monitor) {
-		if (rowIndex >= Integer.MAX_VALUE) {
-			throw new IndexOutOfBoundsException();
-		}
-		final T rowObj= this.list.get((int) rowIndex);
-		return this.columnAccessor.getDataValue(rowObj, columnIndex);
-	}
-	
-	@Override
-	public void setDataValue(final long columnIndex, final long rowIndex, final Object newValue) {
-		if (rowIndex >= Integer.MAX_VALUE) {
-			throw new IndexOutOfBoundsException();
-		}
-		final T rowObj= this.list.get((int) rowIndex);
-		this.columnAccessor.setDataValue(rowObj, columnIndex, newValue);
-	}
-	
-	@Override
 	public T getRowObject(final long rowIndex) {
 		if (rowIndex >= Integer.MAX_VALUE) {
 			throw new IndexOutOfBoundsException();
@@ -76,13 +69,22 @@ public class ListDataProvider<T> implements IRowDataProvider<T> {
 		return this.list.get((int) rowIndex);
 	}
 	
-	@Override
 	public long indexOfRowObject(final T rowObject) {
 		return this.list.indexOf(rowObject);
 	}
 	
-	public List<T> getList() {
-		return this.list;
+	@Override
+	public @Nullable Object getDataValue(final long columnIndex, final long rowIndex,
+			final int flags, final @Nullable IProgressMonitor monitor) {
+		final var rowObject= getRowObject(rowIndex);
+		return this.columnAccessor.getDataValue(rowObject, columnIndex);
+	}
+	
+	@Override
+	public void setDataValue(final long columnIndex, final long rowIndex,
+			final @Nullable Object newValue) {
+		final var rowObject= getRowObject(rowIndex);
+		this.columnAccessor.setDataValue(rowObject, columnIndex, newValue);
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ISpanningDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/SpanningDataProvider.java
index bb49173f..341dbc78 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ISpanningDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/data/SpanningDataProvider.java
@@ -11,12 +11,13 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.data;
+package org.eclipse.statet.ecommons.waltable.core.data;
 
-import org.eclipse.statet.ecommons.waltable.layer.cell.DataCell;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 
-public interface ISpanningDataProvider extends IDataProvider {
+@NonNullByDefault
+public interface SpanningDataProvider extends DataProvider {
 	
 	
 	DataCell getCellByPosition(long columnPosition, long rowPosition);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/AbstractLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/AbstractLayer.java
new file mode 100644
index 00000000..e3dd8189
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/AbstractLayer.java
@@ -0,0 +1,325 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullLateInit;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import org.eclipse.statet.jcommons.collections.CopyOnWriteIdentityListSet;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.config.IConfiguration;
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PixelOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.swt.painters.GridLineCellLayerPainter;
+import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
+
+
+/**
+ * Base layer implementation with common methods for managing listeners and caching, etc.
+ * 
+ * @param <TLayerDim> the type of the layer dimension
+ */
+@NonNullByDefault
+public abstract class AbstractLayer<TLayerDim extends LayerDim> implements Layer {
+	
+	
+	private TLayerDim hDim= nonNullLateInit();
+	private TLayerDim vDim= nonNullLateInit();
+	
+	private @Nullable LayerPainter layerPainter;
+	private ClientAreaProvider clientAreaProvider= ClientAreaProvider.DEFAULT;
+	
+	private final Map<Class<? extends LayerCommand>, LayerCommandHandler<? extends LayerCommand>> commandHandlers= new LinkedHashMap<>();
+	private final CopyOnWriteIdentityListSet<LayerListener> eventHandlers= new CopyOnWriteIdentityListSet<>();
+	
+	private final CopyOnWriteIdentityListSet<Persistable> persistables= new CopyOnWriteIdentityListSet<>();
+	private final CopyOnWriteIdentityListSet<LayerListener> listeners= new CopyOnWriteIdentityListSet<>();
+	
+	private final Collection<IConfiguration> configurations= new ArrayList<>();
+	
+	
+	protected AbstractLayer() {
+	}
+	
+	protected AbstractLayer(@Nullable final LayerPainter layerPainter) {
+		this.layerPainter= layerPainter;
+	}
+	
+	
+	protected void init() {
+		this.hDim= createDim(HORIZONTAL);
+		this.vDim= createDim(VERTICAL);
+		if (this.hDim.getOrientation() != HORIZONTAL || this.vDim.getOrientation() != VERTICAL) {
+			throw new RuntimeException("Invalid LayerDim");
+		}
+	}
+	
+	// Dims
+	
+	protected abstract TLayerDim createDim(Orientation orientation);
+	
+	@Override
+	public TLayerDim getDim(final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return this.hDim;
+		case VERTICAL:
+			return this.vDim;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	
+	// Dispose
+	
+	@Override
+	public void dispose() {
+	}
+	
+	
+	// Regions
+	
+	@Override
+	public LabelStack getRegionLabelsByXY(final long x, final long y) {
+		return new LabelStack();
+	}
+	
+	// Persistence
+	
+	@Override
+	public void saveState(final String prefix, final Map<String, String> properties) {
+		for (final Persistable persistable : this.persistables) {
+			persistable.saveState(prefix, properties);
+		}
+	}
+	
+	@Override
+	public void loadState(final String prefix, final Map<String, String> properties) {
+		for (final Persistable persistable : this.persistables) {
+			persistable.loadState(prefix, properties);
+		}
+	}
+	  
+	@Override
+	public void registerPersistable(final Persistable persistable){
+		this.persistables.add(persistable);
+	}
+
+	@Override
+	public void unregisterPersistable(final Persistable persistable){
+		this.persistables.remove(persistable);
+	}
+	
+	// Configuration
+	
+	public void addConfiguration(final IConfiguration configuration) {
+		this.configurations.add(configuration);
+	}
+
+	public void clearConfiguration() {
+		this.configurations.clear();
+	}
+	
+	@Override
+	public void configure(final ConfigRegistry configRegistry, final UiBindingRegistry uiBindingRegistry) {
+		for (final IConfiguration configuration : this.configurations) {
+			configuration.configureLayer(this);
+			configuration.configureRegistry(configRegistry);
+			configuration.configureUiBindings(uiBindingRegistry);
+		}
+	}
+	
+	// Commands
+	
+	@Override
+	@SuppressWarnings("unchecked")
+	public boolean doCommand(final LayerCommand command) {
+		for (final var entry : this.commandHandlers.entrySet()) {
+			if (entry.getKey().isInstance(command)) {
+				final LayerCommandHandler commandHandler= entry.getValue();
+				if (commandHandler.doCommand(this, command.cloneCommand())) {
+					return true;
+				}
+			}
+		}
+		
+		return false;
+	}
+	
+	// Command handlers
+	
+	/**
+	 * Layers should use this method to register their command handlers
+	 * and call it from their constructor. This allows easy overriding if 
+	 * required of command handlers 
+	 */
+	protected void registerCommandHandlers() {
+		// No op
+	}
+	
+	@Override
+	public void registerCommandHandler(final LayerCommandHandler<?> commandHandler) {
+		this.commandHandlers.put(commandHandler.getCommandClass(), commandHandler);
+	}
+	
+	@Override
+	public void unregisterCommandHandler(final Class<? extends LayerCommand> commandClass) {
+		this.commandHandlers.remove(commandClass);
+	}
+	
+	// Events
+	
+	@Override
+	public void addLayerListener(final LayerListener listener) {
+		this.listeners.add(listener);
+	}
+	
+	@Override
+	public void removeLayerListener(final LayerListener listener) {
+		this.listeners.remove(listener);
+	}
+	
+	/**
+	 * Handle layer event notification. Convert it to your context
+	 * and propagate <i>UP</i>.
+	 *  
+	 * If you override this method you <strong>MUST NOT FORGET</strong> to raise
+	 * the event up the layer stack by calling <code>super.fireLayerEvent(event)</code>
+	 * - unless you plan to eat the event yourself.
+	 **/
+	@Override
+	public void handleLayerEvent(final LayerEvent event) {
+		for (final var handler : this.eventHandlers) {
+			handler.handleLayerEvent(event);
+		}
+		
+		final var localEvent= event.toLayer(this);
+		// Pass on the event to our parent
+		if (localEvent != null) {
+			fireLayerEvent(localEvent);
+		}
+	}
+	
+	public void registerEventHandler(final LayerListener eventHandler) {
+		this.eventHandlers.add(eventHandler);
+	}
+	
+	public void unregisterEventHandler(final LayerListener eventHandler) {
+		this.eventHandlers.remove(eventHandler);
+	}
+	
+	/**
+	 * Pass the event to all the {@link LayerListener} registered on this layer.
+	 * A cloned copy is passed to each listener.
+	 */
+	@Override
+	public void fireLayerEvent(final LayerEvent event) {
+		for (final var listener : this.listeners) {
+			listener.handleLayerEvent(event);
+		}
+	}
+	
+	/**
+	 * @return {@link LayerPainter}. Defaults to {@link GridLineCellLayerPainter}
+	 */
+	@Override
+	public LayerPainter getLayerPainter() {
+		var layerPainter= this.layerPainter;
+		if (layerPainter == null) {
+			layerPainter= createPainter();
+			this.layerPainter= layerPainter;
+		}
+		return layerPainter;
+	}
+	
+	protected LayerPainter createPainter() {
+		return new GridLineCellLayerPainter();
+	}
+	
+	
+	// Client area
+	
+	@Override
+	public ClientAreaProvider getClientAreaProvider() {
+		return this.clientAreaProvider;
+	}
+	
+	@Override
+	public void setClientAreaProvider(final ClientAreaProvider clientAreaProvider) {
+		this.clientAreaProvider= clientAreaProvider;
+	}
+	
+	
+	@Override
+	public final long getColumnCount() {
+		return this.hDim.getPositionCount();
+	}
+	
+	@Override
+	public final long getWidth() {
+		return this.hDim.getSize();
+	}
+	
+	@Override
+	public final long getColumnPositionByX(final long x) {
+		try {
+			return this.hDim.getPositionByPixel(x);
+		}
+		catch (final PixelOutOfBoundsException e) {
+			return Long.MIN_VALUE;
+		}
+	}
+	
+	
+	@Override
+	public final long getRowCount() {
+		return this.vDim.getPositionCount();
+	}
+	
+	@Override
+	public final long getHeight() {
+		return this.vDim.getSize();
+	}
+	
+	@Override
+	public final long getRowPositionByY(final long y) {
+		try {
+			return this.vDim.getPositionByPixel(y);
+		}
+		catch (final PixelOutOfBoundsException e) {
+			return Long.MIN_VALUE;
+		}
+	}
+	
+	
+	@Override
+	public String toString() {
+		return getClass().getSimpleName();
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/AbstractLayerDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/AbstractLayerDim.java
index 34a8a214..4a05d282 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/AbstractLayerDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/AbstractLayerDim.java
@@ -12,9 +12,13 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
 
 
 /**
@@ -22,7 +26,8 @@ import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
  * 
  * @param <TLayer> the type of the layer
  */
-public abstract class AbstractLayerDim<TLayer extends ILayer> implements ILayerDim {
+@NonNullByDefault
+public abstract class AbstractLayerDim<TLayer extends Layer> implements LayerDim {
 	
 	
 	protected final TLayer layer;
@@ -30,20 +35,14 @@ public abstract class AbstractLayerDim<TLayer extends ILayer> implements ILayerD
 	protected final Orientation orientation;
 	
 	
-	public AbstractLayerDim(/*@NonNull*/ final TLayer layer, /*@NonNull*/ final Orientation orientation) {
-		if (layer == null) {
-			throw new NullPointerException("layer"); //$NON-NLS-1$
-		}
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
-		}
-		this.layer= layer;
-		this.orientation= orientation;
+	public AbstractLayerDim(final TLayer layer, final Orientation orientation) {
+		this.layer= nonNullAssert(layer);
+		this.orientation= nonNullAssert(orientation);
 	}
 	
 	
 	@Override
-	public ILayer getLayer() {
+	public Layer getLayer() {
 		return this.layer;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/LayerCell.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/BasicLayerCell.java
index 7ff4a657..3ccf3c65 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/LayerCell.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/BasicLayerCell.java
@@ -11,36 +11,37 @@
  #     Edwin Park - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer.cell;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.data.ControlData;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.data.ControlData;
 
-public class LayerCell implements ILayerCell {
+
+@NonNullByDefault
+public class BasicLayerCell implements LayerCell {
 	
 	
 	private static final ControlData NO_DATA= new ControlData(0, ""); //$NON-NLS-1$
 	
 	
-	private final ILayer layer;
+	private final Layer layer;
 	
-	private final ILayerCellDim h;
-	private final ILayerCellDim v;
+	private final LayerCellDim h;
+	private final LayerCellDim v;
 	
 	
-	public LayerCell(final ILayer layer,
-			final ILayerCellDim horizontalDim, final ILayerCellDim verticalDim) {
+	public BasicLayerCell(final Layer layer,
+			final LayerCellDim horizontalDim, final LayerCellDim verticalDim) {
 		this.layer= layer;
 		this.h= horizontalDim;
 		this.v= verticalDim;
@@ -48,17 +49,20 @@ public class LayerCell implements ILayerCell {
 	
 	
 	@Override
-	public final ILayer getLayer() {
+	public final Layer getLayer() {
 		return this.layer;
 	}
 	
 	@Override
-	public final ILayerCellDim getDim(final Orientation orientation) {
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
+	public final LayerCellDim getDim(final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return this.h;
+		case VERTICAL:
+			return this.v;
+		default:
+			throw new IllegalStateException();
 		}
-		
-		return (orientation == HORIZONTAL) ? this.h : this.v;
 	}
 	
 	
@@ -104,12 +108,13 @@ public class LayerCell implements ILayerCell {
 	}
 	
 	@Override
-	public LabelStack getConfigLabels() {
+	public LabelStack getLabels() {
 		return new LabelStack();
 	}
 	
 	@Override
-	public Object getDataValue(final int flags, final IProgressMonitor monitor) {
+	public @Nullable Object getDataValue(final int flags,
+			final @Nullable IProgressMonitor monitor) {
 		return NO_DATA;
 	}
 	
@@ -120,25 +125,25 @@ public class LayerCell implements ILayerCell {
 		final long yOffset;
 		final long width;
 		final long height;
-		{	final ILayerCellDim dim= getDim(HORIZONTAL);
+		{	final LayerCellDim dim= getDim(HORIZONTAL);
 			
 			final long cellPosition= dim.getPosition();
 			final long firstPosition= dim.getOriginPosition();
 			final long lastPosition= firstPosition + dim.getPositionSpan() - 1;
 			
-			final ILayerDim layerDim= getLayer().getDim(HORIZONTAL);
+			final LayerDim layerDim= getLayer().getDim(HORIZONTAL);
 			xOffset= layerDim.getPositionStart(cellPosition, firstPosition);
 			width= (firstPosition == lastPosition) ?
 					layerDim.getPositionSize(cellPosition, lastPosition) :
 					layerDim.getPositionStart(cellPosition, lastPosition) - xOffset + layerDim.getPositionSize(cellPosition, lastPosition);
 		}
-		{	final ILayerCellDim dim= getDim(VERTICAL);
+		{	final LayerCellDim dim= getDim(VERTICAL);
 			
 			final long cellPosition= dim.getPosition();
 			final long firstPosition= dim.getOriginPosition();
 			final long lastPosition= firstPosition + dim.getPositionSpan() - 1;
 			
-			final ILayerDim layerDim= getLayer().getDim(VERTICAL);
+			final LayerDim layerDim= getLayer().getDim(VERTICAL);
 			yOffset= layerDim.getPositionStart(cellPosition, firstPosition);
 			height= (firstPosition == lastPosition) ?
 					layerDim.getPositionSize(cellPosition, lastPosition) :
@@ -159,17 +164,17 @@ public class LayerCell implements ILayerCell {
 	}
 	
 	@Override
-	public boolean equals(final Object obj) {
+	public boolean equals(final @Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}
-		if (!(obj instanceof ILayerCell)) {
-			return false;
+		if (obj instanceof LayerCell) {
+			final LayerCell other= (LayerCell)obj;
+			return (this.layer.equals(other.getLayer())
+					&& this.h.equals(other.getDim(HORIZONTAL))
+					&& this.v.equals(other.getDim(VERTICAL)) );
 		}
-		final ILayerCell other= (ILayerCell) obj;
-		return (this.layer.equals(other.getLayer())
-				&& this.h.equals(other.getDim(HORIZONTAL))
-				&& this.v.equals(other.getDim(VERTICAL)) );
+		return false;
 	}
 	
 	@Override
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/LayerCellDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/BasicLayerCellDim.java
index 90649591..e46d8676 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/LayerCellDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/BasicLayerCellDim.java
@@ -12,12 +12,20 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer.cell;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
 
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-public class LayerCellDim implements ILayerCellDim {
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+
+
+@NonNullByDefault
+public class BasicLayerCellDim implements LayerCellDim {
 	
 	
 	private final Orientation orientation;
@@ -30,20 +38,17 @@ public class LayerCellDim implements ILayerCellDim {
 	private final long positionSpan;
 	
 	
-	public LayerCellDim(final Orientation orientation, final long id,
+	public BasicLayerCellDim(final Orientation orientation, final long id,
 			final long position) {
 		this(orientation, id, position, position, 1);
 	}
 	
-	public LayerCellDim(final Orientation orientation, final long id,
+	public BasicLayerCellDim(final Orientation orientation, final long id,
 			final long position, final long originPosition, final long positionSpan) {
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
-		}
 		if (positionSpan < 0 || position < originPosition || position >= originPosition + positionSpan) {
 			throw new IllegalArgumentException("position: " + position + " [" + originPosition + ", " + (originPosition + positionSpan) + "]"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
 		}
-		this.orientation= orientation;
+		this.orientation= nonNullAssert(orientation);
 		this.id= id;
 		this.position= position;
 		this.originPosition= originPosition;
@@ -80,19 +85,19 @@ public class LayerCellDim implements ILayerCellDim {
 	@Override
 	public final int hashCode() {
 		int h= (int) (this.originPosition ^ (this.originPosition >>> 32));
-		if (this.orientation == Orientation.VERTICAL) {
+		if (this.orientation == VERTICAL) {
 			h= 17 + Integer.rotateRight(h, 15);
 		}
 		return h ^ (h >>> 7);
 	}
 	
 	@Override
-	public final boolean equals(final Object obj) {
+	public final boolean equals(final @Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}
-		if (obj instanceof LayerCellDim) {
-			final LayerCellDim other= (LayerCellDim) obj;
+		if (obj instanceof BasicLayerCellDim) {
+			final BasicLayerCellDim other= (BasicLayerCellDim)obj;
 			return (this.orientation == other.orientation
 					&& this.originPosition == other.originPosition
 					&& this.positionSpan == other.positionSpan);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/IClientAreaProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/ClientAreaProvider.java
index d61d1868..b0b442c3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/IClientAreaProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/ClientAreaProvider.java
@@ -11,23 +11,25 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.ui;
+package org.eclipse.statet.ecommons.waltable.core.layer;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
 
 
 /**
- * Specifies the rectangular area available to an {@link ILayer}
- * Note: All layers get the client area from {@link NatTable} which implements this interface. 
+ * Specifies the rectangular area available to an {@link Layer}
+ * Note: All layers get the client area from {@link NatTable} which implements this interface.
  * 
- * @see ILayer#getClientAreaProvider()
+ * @see Layer#getClientAreaProvider()
  */
-public interface IClientAreaProvider {
+@NonNullByDefault
+public interface ClientAreaProvider {
 	
 	
-	IClientAreaProvider DEFAULT= new IClientAreaProvider() {
+	static final ClientAreaProvider DEFAULT= new ClientAreaProvider() {
 		@Override
 		public LRectangle getClientArea() {
 			return new LRectangle(0, 0, 0, 0);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/CompositeLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/CompositeLayer.java
index 60ffb367..7fc908df 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/CompositeLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/CompositeLayer.java
@@ -11,41 +11,44 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
 
-import java.util.Properties;
+import java.util.Map;
 
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Rectangle;
 
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.config.ConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.jcommons.lang.NonNull;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
 import org.eclipse.statet.ecommons.waltable.layer.cell.AggregrateConfigLabelAccumulator;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ForwardLayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.IConfigLabelAccumulator;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCellDim;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCellDim;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-import org.eclipse.statet.ecommons.waltable.ui.IClientAreaProvider;
+import org.eclipse.statet.ecommons.waltable.layer.cell.CellLabelContributor;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 
 
 /**
- * A composite layer is a layer that is made up of a number of underlying child layers. This class assumes that the child
- * layers are laid out in a regular grid pattern where the child layers in each composite row all have the same number of
- * rows and the same height, and the child layers in each composite column each have the same number of columns and
- * the same width.
+ * A composite layer is a layer that is made up of a number of underlying
+ * child layers.
+ * 
+ * <p>This class assumes that the child layers are laid out in a regular grid
+ * pattern where the child layers in each composite row all have the same
+ * number of rows and the same height, and the child layers in each composite
+ * column each have the same number of columns and the same width.</p>
  */
-public class CompositeLayer extends AbstractLayer {
+@NonNullByDefault
+public class CompositeLayer extends AbstractLayer<CompositeLayerDim> {
 	
 	
 	protected static final class Child {
@@ -55,12 +58,12 @@ public class CompositeLayer extends AbstractLayer {
 		
 		public final String label;
 		
-		public final ILayer layer;
+		public final Layer layer;
 		
-		private IConfigLabelAccumulator configLabelAccumulator;
+		private CellLabelContributor configLabelAccumulator;
 		
 		
-		private Child(final int x, final int y, final String label, final ILayer layer) {
+		private Child(final int x, final int y, final String label, final Layer layer) {
 			this.layoutX= x;
 			this.layoutY= y;
 			this.label= label;
@@ -75,43 +78,32 @@ public class CompositeLayer extends AbstractLayer {
 	protected final int layoutYCount;
 	
 	/** Data struct. for child Layers */
-	private final Child[][] childLayout;
+	private final @NonNull Child [] @NonNull [] childLayout;
 	
 	
 	public CompositeLayer(final int layoutXCount, final int layoutYCount) {
 		this.layoutXCount= layoutXCount;
 		this.layoutYCount= layoutYCount;
-		this.childLayout= new Child[layoutXCount][layoutYCount];
+		this.childLayout= new @NonNull Child @NonNull [layoutXCount] @NonNull [layoutYCount];
 		
-		initDims();
+		init();
 	}
 	
-	
 	@Override
-	protected void initDims() {
-		if (this.childLayout == null) {
-			return;
-		}
-		
-		for (final Orientation orientation : Orientation.values()) {
-			setDim((ignoreRef(orientation)) ?
+	protected CompositeLayerDim createDim(final Orientation orientation) {
+		return (ignoreRef(orientation)) ?
 					new CompositeLayerDim.IgnoreRef(this, orientation) :
-					new CompositeLayerDim(this, orientation) );
-		}
+					new CompositeLayerDim(this, orientation);
 	}
 	
 	protected boolean ignoreRef(final Orientation orientation) {
 		return false;
 	}
 	
-	final CompositeLayerDim get(final Orientation orientation) {
-		return (CompositeLayerDim) getDim(orientation);
-	}
-	
 	
 	@Override
-	protected ILayerPainter createPainter() {
-		return new CompositeLayerPainter();
+	protected LayerPainter createPainter() {
+		return new CompositeLayerPainter(this);
 	}
 	
 	
@@ -132,7 +124,7 @@ public class CompositeLayer extends AbstractLayer {
 	// Persistence
 	
 	@Override
-	public void saveState(final String prefix, final Properties properties) {
+	public void saveState(final String prefix, final Map<String, String> properties) {
 		for (int layoutX= 0; layoutX < this.layoutXCount; layoutX++) {
 			for (int layoutY= 0; layoutY < this.layoutYCount; layoutY++) {
 				final Child child= this.childLayout[layoutX][layoutY];
@@ -145,7 +137,7 @@ public class CompositeLayer extends AbstractLayer {
 	}
 	
 	@Override
-	public void loadState(final String prefix, final Properties properties) {
+	public void loadState(final String prefix, final Map<String, String> properties) {
 		for (int layoutX= 0; layoutX < this.layoutXCount; layoutX++) {
 			for (int layoutY= 0; layoutY < this.layoutYCount; layoutY++) {
 				final Child child= this.childLayout[layoutX][layoutY];
@@ -175,14 +167,14 @@ public class CompositeLayer extends AbstractLayer {
 	 * Handle commands
 	 */
 	@Override
-	public boolean doCommand(final ILayerCommand command) {
+	public boolean doCommand(final LayerCommand command) {
 		if (super.doCommand(command)) {
 			return true;
 		}
 		return doCommandOnChildLayers(command);
 	}
 	
-	protected boolean doCommandOnChildLayers(final ILayerCommand command) {
+	protected boolean doCommandOnChildLayers(final LayerCommand command) {
 		for (int layoutX= 0; layoutX < this.layoutXCount; layoutX++) {
 			for (int layoutY= 0; layoutY < this.layoutYCount; layoutY++) {
 				if (this.childLayout[layoutX][layoutY].layer.doCommand(command)) {
@@ -196,29 +188,29 @@ public class CompositeLayer extends AbstractLayer {
 	// Cell features
 	
 	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
 		final Child child= getChildByPosition(columnPosition, rowPosition);
 		
 		if (child == null) {
 			throw new PositionOutOfBoundsException(columnPosition + ", " + rowPosition); //$NON-NLS-1$
 		}
 		
-		final long childColumnPosition= columnPosition - get(HORIZONTAL).getLayoutPosition(child.layoutX);
-		final long childRowPosition= rowPosition - get(VERTICAL).getLayoutPosition(child.layoutY);
+		final long childColumnPosition= columnPosition - getDim(HORIZONTAL).getLayoutPosition(child.layoutX);
+		final long childRowPosition= rowPosition - getDim(VERTICAL).getLayoutPosition(child.layoutY);
 		
-		final ILayerCell underlyingCell= child.layer.getCellByPosition(childColumnPosition, childRowPosition);
+		final LayerCell underlyingCell= child.layer.getCellByPosition(childColumnPosition, childRowPosition);
 		
-		final ILayerCellDim hDim= transformCellDim(underlyingCell.getDim(HORIZONTAL), columnPosition);
-		final ILayerCellDim vDim= transformCellDim(underlyingCell.getDim(VERTICAL), rowPosition);
+		final LayerCellDim hDim= transformCellDim(underlyingCell.getDim(HORIZONTAL), columnPosition);
+		final LayerCellDim vDim= transformCellDim(underlyingCell.getDim(VERTICAL), rowPosition);
 		
 		return new ForwardLayerCell(this, hDim, vDim, underlyingCell) {
 			
 			@Override
-			public LabelStack getConfigLabels() {
-				final LabelStack configLabels= super.getConfigLabels();
+			public LabelStack getLabels() {
+				final LabelStack configLabels= super.getLabels();
 				
 				if (child.configLabelAccumulator != null) {
-					child.configLabelAccumulator.accumulateConfigLabels(configLabels, childColumnPosition, childRowPosition);
+					child.configLabelAccumulator.addLabels(configLabels, childColumnPosition, childRowPosition);
 				}
 				
 				configLabels.addLabel(child.label);
@@ -229,31 +221,27 @@ public class CompositeLayer extends AbstractLayer {
 		};
 	}
 	
-	protected ILayerCellDim transformCellDim(final ILayerCellDim underlyingDim, final long position) {
+	protected LayerCellDim transformCellDim(final LayerCellDim underlyingDim, final long position) {
 		final long originPosition= (underlyingDim.getPosition() == underlyingDim.getOriginPosition()) ?
 				position :
-				get(underlyingDim.getOrientation()).underlyingToLocalPosition(
+				getDim(underlyingDim.getOrientation()).underlyingToLocalPosition(
 						position, underlyingDim.getOriginPosition() );
-		return new LayerCellDim(underlyingDim.getOrientation(), underlyingDim.getId(),
+		return new BasicLayerCellDim(underlyingDim.getOrientation(), underlyingDim.getId(),
 				position, originPosition, underlyingDim.getPositionSpan() );
 	}
 	
 	// Child layer stuff
 	
-	public void setChildLayer(final String label, final ILayer childLayer, final int layoutX, final int layoutY) {
-		if (childLayer == null) {
-			throw new IllegalArgumentException("Cannot set null child layer"); //$NON-NLS-1$
-		}
-		
-		final Child child= new Child(layoutX, layoutY, label, childLayer);
+	public void setChildLayer(final String label, final Layer childLayer, final int layoutX, final int layoutY) {
+		final Child child= new Child(layoutX, layoutY, label, nonNullAssert(childLayer));
 		
 		childLayer.addLayerListener(this);
 		this.childLayout[layoutX][layoutY]= child;
 		
-		get(HORIZONTAL).updateChild(layoutX, layoutY, childLayer);
-		get(VERTICAL).updateChild(layoutY, layoutX, childLayer);
+		getDim(HORIZONTAL).setChild(layoutX, layoutY, childLayer);
+		getDim(VERTICAL).setChild(layoutY, layoutX, childLayer);
 		
-		childLayer.setClientAreaProvider(new IClientAreaProvider() {
+		childLayer.setClientAreaProvider(new ClientAreaProvider() {
 			@Override
 			public LRectangle getClientArea() {
 				return getChildClientArea(child);
@@ -264,10 +252,10 @@ public class CompositeLayer extends AbstractLayer {
 	/**
 	 * Adds the configLabelAccumulator to the existing label accumulators.
 	 */
-	public void addConfigLabelAccumulatorForRegion(final String regionLabel, final IConfigLabelAccumulator configLabelAccumulator) {
+	public void addCellLabelContributor(final String regionLabel, final CellLabelContributor labelContributor) {
 		final Child child= getChildByLabel(regionLabel);
 		if (child.configLabelAccumulator == null) {
-			child.configLabelAccumulator= configLabelAccumulator;
+			child.configLabelAccumulator= labelContributor;
 		}
 		else {
 			final AggregrateConfigLabelAccumulator aggregateAccumulator;
@@ -279,7 +267,7 @@ public class CompositeLayer extends AbstractLayer {
 				aggregateAccumulator.add(child.configLabelAccumulator);
 				child.configLabelAccumulator= aggregateAccumulator;
 			}
-			aggregateAccumulator.add(configLabelAccumulator);
+			aggregateAccumulator.add(labelContributor);
 		}
 	}
 	
@@ -287,8 +275,8 @@ public class CompositeLayer extends AbstractLayer {
 		final LRectangle compositeClientArea= getClientAreaProvider().getClientArea();
 		
 		final LRectangle childClientArea= new LRectangle(
-				compositeClientArea.x + get(HORIZONTAL).getLayoutStart(child.layoutX),
-				compositeClientArea.y + get(VERTICAL).getLayoutStart(child.layoutY),
+				compositeClientArea.x + getDim(HORIZONTAL).getLayoutStart(child.layoutX),
+				compositeClientArea.y + getDim(VERTICAL).getLayoutStart(child.layoutY),
 				child.layer.getDim(HORIZONTAL).getPreferredSize(),
 				child.layer.getDim(VERTICAL).getPreferredSize() );
 		
@@ -302,7 +290,7 @@ public class CompositeLayer extends AbstractLayer {
 	 * @param layoutY row position in the CompositeLayer
 	 * @return child layer according to the Composite Layer Layout
 	 */
-	public ILayer getChildLayerByLayoutCoordinate(final int layoutX, final int layoutY) {
+	public @Nullable Layer getChildLayerByLayoutCoordinate(final int layoutX, final int layoutY) {
 		if (layoutX < 0 || layoutX >= this.layoutXCount || layoutY < 0 || layoutY >= this.layoutYCount) {
 			return null;
 		}
@@ -323,8 +311,8 @@ public class CompositeLayer extends AbstractLayer {
 			return null;
 		}
 		
-		final long childX= x - get(HORIZONTAL).getLayoutStart(child.layoutX);
-		final long childY= y - get(VERTICAL).getLayoutStart(child.layoutY);
+		final long childX= x - getDim(HORIZONTAL).getLayoutStart(child.layoutX);
+		final long childY= y - getDim(VERTICAL).getLayoutStart(child.layoutY);
 		final LabelStack regionLabels= child.layer.getRegionLabelsByXY(childX, childY);
 		
 		regionLabels.addLabel(child.label);
@@ -333,14 +321,14 @@ public class CompositeLayer extends AbstractLayer {
 	}
 	
 	@Override
-	public ILayer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
+	public @Nullable Layer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
 		final Child child= getChildByPosition(columnPosition, rowPosition);
 		return (child != null) ? child.layer : null;
 	}
 	
 	// Layout coordinate accessors
 	
-	protected final Child getChildByLabel(final String label) {
+	protected final @Nullable Child getChildByLabel(final String label) {
 		for (int layoutX= 0; layoutX < this.layoutXCount; layoutX++) {
 			for (int layoutY= 0; layoutY < this.layoutYCount; layoutY++) {
 				if (label.equals(this.childLayout[layoutX][layoutY].label)) {
@@ -351,7 +339,7 @@ public class CompositeLayer extends AbstractLayer {
 		return null;
 	}
 	
-	protected final Child getChildByLayer(final ILayer childLayer) {
+	protected final @Nullable Child getChildByLayer(final Layer childLayer) {
 		for (int layoutX= 0; layoutX < this.layoutXCount; layoutX++) {
 			for (int layoutY= 0; layoutY < this.layoutYCount; layoutY++) {
 				if (this.childLayout[layoutX][layoutY].layer == childLayer) {
@@ -362,24 +350,24 @@ public class CompositeLayer extends AbstractLayer {
 		return null;
 	}
 	
-	protected final Child getChildByPixelXY(final long x, final long y) {
-		final int layoutX= get(HORIZONTAL).getLayoutByPixel(x);
+	protected final @Nullable Child getChildByPixelXY(final long x, final long y) {
+		final int layoutX= getDim(HORIZONTAL).getLayoutByPixel(x);
 		if (layoutX < 0) {
 			return null;
 		}
-		final int layoutY= get(VERTICAL).getLayoutByPixel(y);
+		final int layoutY= getDim(VERTICAL).getLayoutByPixel(y);
 		if (layoutY < 0) {
 			return null;
 		}
 		return this.childLayout[layoutX][layoutY];
 	}
 	
-	protected final Child getChildByPosition(final long compositeColumnPosition, final long compositeRowPosition) {
-		final int layoutX= get(HORIZONTAL).getLayoutByPosition(compositeColumnPosition);
+	protected final @Nullable Child getChildByPosition(final long compositeColumnPosition, final long compositeRowPosition) {
+		final int layoutX= getDim(HORIZONTAL).getLayoutByPosition(compositeColumnPosition);
 		if (layoutX < 0) {
 			return null;
 		}
-		final int layoutY= get(VERTICAL).getLayoutByPosition(compositeRowPosition);
+		final int layoutY= getDim(VERTICAL).getLayoutByPosition(compositeRowPosition);
 		if (layoutY < 0) {
 			return null;
 		}
@@ -387,62 +375,76 @@ public class CompositeLayer extends AbstractLayer {
 	}
 	
 	
-	protected class CompositeLayerPainter implements ILayerPainter {
+	public static class CompositeLayerPainter implements LayerPainter {
+		
+		
+		protected final CompositeLayer layer;
+		
+		
+		public CompositeLayerPainter(final CompositeLayer layer) {
+			this.layer= layer;
+		}
+		
 		
 		@Override
-		public void paintLayer(final ILayer natLayer, final GC gc,
+		public LRectangle adjustCellBounds(final long columnPosition, final long rowPosition,
+				final LRectangle cellBounds) {
+			final Child child= this.layer.getChildByPosition(columnPosition, rowPosition);
+			final var hDim= this.layer.getDim(HORIZONTAL);
+			final var vDim= this.layer.getDim(VERTICAL);
+			
+			final long widthOffset= hDim.getLayoutStart(child.layoutX);
+			final long heightOffset= vDim.getLayoutStart(child.layoutY);
+			
+//			LRectangle bounds= new LRectangle(cellBounds.x - widthOffset, cellBounds.y - heightOffset, cellBounds.width, cellBounds.height);
+			cellBounds.x-= widthOffset;
+			cellBounds.y-= heightOffset;
+			
+			final var childLayerPainter= child.layer.getLayerPainter();
+			final long childColumnPosition= columnPosition - hDim.getLayoutPosition(child.layoutX);
+			final long childRowPosition= rowPosition - vDim.getLayoutPosition(child.layoutY);
+			final LRectangle adjustedChildCellBounds= childLayerPainter.adjustCellBounds(childColumnPosition, childRowPosition, cellBounds);
+//			LRectangle adjustedChildCellBounds= childLayerPainter.adjustCellBounds(childColumnPosition, childRowPosition, bounds);
+			
+			adjustedChildCellBounds.x+= widthOffset;
+			adjustedChildCellBounds.y+= heightOffset;
+			
+			return adjustedChildCellBounds;
+		}
+		
+		@Override
+		public void paintLayer(final Layer natLayer, final GC gc,
 				final int xOffset, final int yOffset, final Rectangle pixelRectangle,
-				final IConfigRegistry configuration) {
+				final ConfigRegistry configuration) {
 			int x= xOffset;
-			for (int layoutX= 0; layoutX < CompositeLayer.this.layoutXCount; layoutX++) {
+			for (int layoutX= 0; layoutX < this.layer.layoutXCount; layoutX++) {
 				int y= yOffset;
-				final int width= safe(CompositeLayer.this.childLayout[layoutX][0].layer.getWidth());
-				for (int layoutY= 0; layoutY < CompositeLayer.this.layoutYCount; layoutY++) {
-					final Child child= CompositeLayer.this.childLayout[layoutX][layoutY];
+				final @NonNull Child[] layoutXChilds= this.layer.childLayout[layoutX];
+				final int width= safe(layoutXChilds[0].layer.getWidth());
+				for (int layoutY= 0; layoutY < this.layer.layoutYCount; layoutY++) {
+					final Child child= layoutXChilds[layoutY];
+					final int height= safe(child.layer.getHeight());
 					
-					final Rectangle childRectangle= new Rectangle(x, y, width, safe(child.layer.getHeight()) );
+					final Rectangle childRectangle= new Rectangle(x, y, width, height);
 					final Rectangle childPaintRectangle= pixelRectangle.intersection(childRectangle);
 					
 					if (!childPaintRectangle.isEmpty()) {
 						final Rectangle originalClipping= gc.getClipping();
 						gc.setClipping(childPaintRectangle);
 						
-						child.layer.getLayerPainter().paintLayer(natLayer, gc,
-								x, y, childPaintRectangle, configuration );
+						final var layerPainter= child.layer.getLayerPainter();
+						layerPainter.paintLayer(natLayer, gc, x, y, childPaintRectangle, configuration);
 						
 						gc.setClipping(originalClipping);
 					}
 					
-					y+= childRectangle.height;
+					y+= height;
 				}
 				
 				x+= width;
 			}
 		}
 		
-		@Override
-		public LRectangle adjustCellBounds(final long columnPosition, final long rowPosition, final LRectangle cellBounds) {
-			final Child child= getChildByPosition(columnPosition, rowPosition);
-			
-			final long widthOffset= get(HORIZONTAL).getLayoutStart(child.layoutX);
-			final long heightOffset= get(VERTICAL).getLayoutStart(child.layoutY);
-			
-//			LRectangle bounds= new LRectangle(cellBounds.x - widthOffset, cellBounds.y - heightOffset, cellBounds.width, cellBounds.height);
-			cellBounds.x-= widthOffset;
-			cellBounds.y-= heightOffset;
-			
-			final ILayerPainter childLayerPainter= child.layer.getLayerPainter();
-			final long childColumnPosition= columnPosition - get(HORIZONTAL).getLayoutPosition(child.layoutX);
-			final long childRowPosition= rowPosition - get(VERTICAL).getLayoutPosition(child.layoutY);
-			final LRectangle adjustedChildCellBounds= childLayerPainter.adjustCellBounds(childColumnPosition, childRowPosition, cellBounds);
-//			LRectangle adjustedChildCellBounds= childLayerPainter.adjustCellBounds(childColumnPosition, childRowPosition, bounds);
-			
-			adjustedChildCellBounds.x+= widthOffset;
-			adjustedChildCellBounds.y+= heightOffset;
-			
-			return adjustedChildCellBounds;
-		}
-		
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/CompositeLayerDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/CompositeLayerDim.java
index cff68c25..74e6d770 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/CompositeLayerDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/CompositeLayerDim.java
@@ -12,20 +12,27 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.coordinate.PixelOutOfBoundsException;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNull;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PixelOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
 
+
+@NonNullByDefault
 public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 	
 	
@@ -62,15 +69,15 @@ public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 	}
 	
 	
-	private final ILayerDim[][] childDims;
+	private final @NonNull LayerDim [] @NonNull [] childDims;
 	
 	
 	public CompositeLayerDim(final CompositeLayer layer, final Orientation orientation) {
 		super(layer, orientation);
 		
 		this.childDims= (orientation == HORIZONTAL) ?
-				new ILayerDim[layer.layoutXCount][layer.layoutYCount] :
-				new ILayerDim[layer.layoutYCount][layer.layoutXCount];
+				new @NonNull LayerDim @NonNull [layer.layoutXCount] @NonNull [layer.layoutYCount] :
+				new @NonNull LayerDim @NonNull [layer.layoutYCount] @NonNull [layer.layoutXCount];
 	}
 	
 	
@@ -80,7 +87,7 @@ public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 	}
 	
 	
-	void updateChild(final int layout, final int layout2, final ILayer childLayer) {
+	void setChild(final int layout, final int layout2, final Layer childLayer) {
 		this.childDims[layout][layout2]= childLayer.getDim(this.orientation);
 	}
 	
@@ -108,9 +115,9 @@ public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 		return -1;
 	}
 	
-	protected final int getLayoutByDim(final ILayerDim childDim) {
+	protected final int getLayoutByDim(final LayerDim childDim) {
 		for (int layout= 0; layout < this.childDims.length; layout++) {
-			final ILayerDim[] layoutDims= this.childDims[layout];
+			final LayerDim[] layoutDims= this.childDims[layout];
 			for (int layout2= 0; layout2 < layoutDims.length; layout2++) {
 				if (layoutDims[layout2] == childDim) {
 					return layout;
@@ -195,7 +202,7 @@ public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 	}
 	
 	@Override
-	public long underlyingToLocalPosition(final ILayerDim sourceUnderlyingDim,
+	public long underlyingToLocalPosition(final LayerDim sourceUnderlyingDim,
 			final long underlyingPosition) {
 		final int layout= getLayoutByDim(sourceUnderlyingDim);
 		if (layout < 0) {
@@ -207,7 +214,7 @@ public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 	}
 	
 	@Override
-	public List<LRange> underlyingToLocalPositions(final ILayerDim sourceUnderlyingDim,
+	public List<LRange> underlyingToLocalPositions(final LayerDim sourceUnderlyingDim,
 			final Collection<LRange> underlyingPositionRanges) {
 		final int layout= getLayoutByDim(sourceUnderlyingDim);
 		if (layout < 0) {
@@ -227,20 +234,13 @@ public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 	}
 	
 	@Override
-	public List<ILayerDim> getUnderlyingDimsByPosition(final long position) {
+	public @Nullable ImList<LayerDim> getUnderlyingDimsByPosition(final long position) {
 		final int layout= getLayoutByPosition(position);
 		if (layout < 0) {
 			return null;
 		}
 		
-		final List<ILayerDim> underlyingDims= new ArrayList<>(this.childDims.length);
-		
-		final ILayerDim[] layoutDims= this.childDims[layout];
-		for (int layout2= 0; layout2 < layoutDims.length; layout2++) {
-			underlyingDims.add(layoutDims[layout2]);
-		}
-		
-		return underlyingDims;
+		return ImCollections.newList(this.childDims[layout]);
 	}
 	
 	
@@ -266,7 +266,7 @@ public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 	public long getPositionByPixel(final long pixel) {
 		final int layout= getLayoutByPixel(pixel);
 		if (layout < 0) {
-			throw PixelOutOfBoundsException.pixel(pixel, getOrientation());
+			throw new PixelOutOfBoundsException(pixel, getOrientation());
 		}
 		
 		final long childPosition= this.childDims[layout][0].getPositionByPixel(
@@ -290,7 +290,7 @@ public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 	public long getPositionStart(final long position) {
 		final int layout= getLayoutByPosition(position);
 		if (layout < 0) {
-			throw PositionOutOfBoundsException.position(position, getOrientation());
+			throw new PositionOutOfBoundsException(position, getOrientation());
 		}
 		
 		final long layoutPosition= getLayoutPosition(layout);
@@ -314,7 +314,7 @@ public class CompositeLayerDim extends AbstractLayerDim<CompositeLayer> {
 	public int getPositionSize(final long position) {
 		final int layout= getLayoutByPosition(position);
 		if (layout < 0) {
-			throw PositionOutOfBoundsException.position(position, getOrientation());
+			throw new PositionOutOfBoundsException(position, getOrientation());
 		}
 		
 		final long layoutPosition= getLayoutPosition(layout);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/ForwardLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/ForwardLayer.java
new file mode 100644
index 00000000..ad813a22
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/ForwardLayer.java
@@ -0,0 +1,154 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import java.util.Map;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralChangeEvent;
+import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
+
+
+@NonNullByDefault
+public abstract class ForwardLayer<TLayerDim extends ForwardLayerDim<? extends ForwardLayer<TLayerDim>>>
+		extends AbstractLayer<TLayerDim> {
+	
+	
+	private final Layer underlyingLayer;
+	
+	
+	public ForwardLayer(final Layer underlyingLayer,
+			final @Nullable LayerPainter layerPainter) {
+		super(layerPainter);
+		this.underlyingLayer= nonNullAssert(underlyingLayer);
+		this.underlyingLayer.setClientAreaProvider(getClientAreaProvider());
+		this.underlyingLayer.addLayerListener(this);
+	}
+	
+	public ForwardLayer(final Layer underlyingLayer) {
+		this(underlyingLayer, null);
+	}
+	
+	
+	protected final Layer getUnderlyingLayer() {
+		return this.underlyingLayer;
+	}
+	
+	// Dispose
+	
+	@Override
+	public void dispose() {
+		this.underlyingLayer.dispose();
+	}
+	
+	// Persistence
+	
+	@Override
+	public void saveState(final String prefix, final Map<String, String> properties) {
+		this.underlyingLayer.saveState(prefix, properties);
+		super.saveState(prefix, properties);
+	}
+	
+	/**
+	 * Underlying layers <i>must</i> load state first.
+	 * If this is not done, {@link StructuralChangeEvent} from underlying
+	 * layers will reset caches after state has been loaded
+	 */
+	@Override
+	public void loadState(final String prefix, final Map<String, String> properties) {
+		this.underlyingLayer.loadState(prefix, properties);
+		super.loadState(prefix, properties);
+	}
+	
+	// Configuration
+	
+	@Override
+	public void configure(final ConfigRegistry configRegistry, final UiBindingRegistry uiBindingRegistry) {
+		this.underlyingLayer.configure(configRegistry, uiBindingRegistry);
+		super.configure(configRegistry, uiBindingRegistry);
+	}
+	
+	@Override
+	public LayerPainter getLayerPainter() {
+		final var layerPainter= super.getLayerPainter();
+		return (layerPainter != null) ? layerPainter : this.underlyingLayer.getLayerPainter();
+	}
+	
+	@Override
+	@SuppressWarnings("null")
+	protected LayerPainter createPainter() {
+		return null;
+	}
+	
+	
+	// Command
+	
+	@Override
+	public boolean doCommand(final LayerCommand command) {
+		if (super.doCommand(command)) {
+			return true;
+		}
+		
+		return this.underlyingLayer.doCommand(command);
+	}
+	
+	// Client area
+	
+	@Override
+	public void setClientAreaProvider(final ClientAreaProvider clientAreaProvider) {
+		super.setClientAreaProvider(clientAreaProvider);
+		this.underlyingLayer.setClientAreaProvider(clientAreaProvider);
+	}
+	
+	
+	// Cell features
+	
+	@Override
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+		final LayerCell underlyingCell= this.underlyingLayer.getCellByPosition(
+				columnPosition, rowPosition );
+		
+		return createCell(
+				underlyingCell.getDim(HORIZONTAL),
+				underlyingCell.getDim(VERTICAL),
+				underlyingCell );
+	}
+	
+	protected LayerCell createCell(final LayerCellDim hDim, final LayerCellDim vDim,
+			final LayerCell underlyingCell) {
+		return new ForwardLayerCell(this, hDim, vDim, underlyingCell);
+	}
+	
+	// IRegionResolver
+	
+	@Override
+	public LabelStack getRegionLabelsByXY(final long x, final long y) {
+		return this.underlyingLayer.getRegionLabelsByXY(x, y);
+	}
+	
+	@Override
+	public Layer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
+		return this.underlyingLayer;
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ForwardLayerCell.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/ForwardLayerCell.java
index 9ec6e7b7..3bc4934b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ForwardLayerCell.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/ForwardLayerCell.java
@@ -11,31 +11,35 @@
  #     Edwin Park - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer.cell;
+package org.eclipse.statet.ecommons.waltable.core.layer;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
 
 
-public class ForwardLayerCell extends LayerCell {
+@NonNullByDefault
+public class ForwardLayerCell extends BasicLayerCell {
 	
 	
-	private final ILayerCell underlyingCell;
+	private final LayerCell underlyingCell;
 	
 	
-	public ForwardLayerCell(final ILayer layer,
-			final ILayerCellDim horizontalDim, final ILayerCellDim verticalDim,
-			final ILayerCell underlyingCell) {
+	public ForwardLayerCell(final Layer layer,
+			final LayerCellDim horizontalDim, final LayerCellDim verticalDim,
+			final LayerCell underlyingCell) {
 		super(layer, horizontalDim, verticalDim);
 		
-		this.underlyingCell= underlyingCell;
+		this.underlyingCell= nonNullAssert(underlyingCell);
 	}
 	
 	
-	public ILayerCell getUnderlyingCell() {
+	public LayerCell getUnderlyingCell() {
 		return this.underlyingCell;
 	}
 	
@@ -45,13 +49,14 @@ public class ForwardLayerCell extends LayerCell {
 	}
 	
 	@Override
-	public LabelStack getConfigLabels() {
-		return this.underlyingCell.getConfigLabels();
+	public LabelStack getLabels() {
+		return this.underlyingCell.getLabels();
 	}
 	
 	
 	@Override
-	public Object getDataValue(final int flags, final IProgressMonitor monitor) {
+	public @Nullable Object getDataValue(final int flags,
+			final @Nullable IProgressMonitor monitor) {
 		return this.underlyingCell.getDataValue(flags, monitor);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ForwardLayerDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/ForwardLayerDim.java
index a0717429..8dbadc51 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ForwardLayerDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/ForwardLayerDim.java
@@ -12,39 +12,42 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
 
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
 
 
 /**
- * Dim implementation for {@link TransformLayer}.
+ * A layer dimension for a {@link ForwardLayer}.
  * 
- * @param <T> the type of the layer
+ * @param <TLayer> the type of the layer
  */
-public class ForwardLayerDim<T extends ILayer> extends AbstractLayerDim<T> {
+@NonNullByDefault
+public class ForwardLayerDim<TLayer extends Layer> extends AbstractLayerDim<TLayer> {
 	
 	
-	protected final ILayerDim underlyingDim;
+	protected final LayerDim underlyingDim;
 	
 	
-	public ForwardLayerDim(/*@NonNull*/ final T layer, /*@NonNull*/ final ILayerDim underlyingDim) {
+	public ForwardLayerDim(final TLayer layer, final LayerDim underlyingDim) {
 		this(layer, underlyingDim.getOrientation(), underlyingDim);
 	}
 	
-	public ForwardLayerDim(/*@NonNull*/ final T layer, /*@NonNull*/ final Orientation orientation,
-			/*@NonNull*/ final ILayerDim underlyingDim) {
+	public ForwardLayerDim(final TLayer layer, final Orientation orientation,
+			final LayerDim underlyingDim) {
 		super(layer, orientation);
-		if (underlyingDim == null) {
-			throw new NullPointerException("underlyingDim"); //$NON-NLS-1$
-		}
-		this.underlyingDim= underlyingDim;
+		this.underlyingDim= nonNullAssert(underlyingDim);
 	}
 	
 	
@@ -70,7 +73,7 @@ public class ForwardLayerDim<T extends ILayer> extends AbstractLayerDim<T> {
 	}
 	
 	@Override
-	public long underlyingToLocalPosition(final ILayerDim sourceUnderlyingDim,
+	public long underlyingToLocalPosition(final LayerDim sourceUnderlyingDim,
 			final long underlyingPosition) {
 		if (sourceUnderlyingDim != this.underlyingDim) {
 			throw new IllegalArgumentException("underlyingLayer"); //$NON-NLS-1$
@@ -80,7 +83,7 @@ public class ForwardLayerDim<T extends ILayer> extends AbstractLayerDim<T> {
 	}
 	
 	@Override
-	public List<LRange> underlyingToLocalPositions(final ILayerDim sourceUnderlyingDim,
+	public List<LRange> underlyingToLocalPositions(final LayerDim sourceUnderlyingDim,
 			final Collection<LRange> underlyingPositions) {
 		if (sourceUnderlyingDim != this.underlyingDim) {
 			throw new IllegalArgumentException("underlyingLayer"); //$NON-NLS-1$
@@ -90,8 +93,8 @@ public class ForwardLayerDim<T extends ILayer> extends AbstractLayerDim<T> {
 	}
 	
 	@Override
-	public List<ILayerDim> getUnderlyingDimsByPosition(final long position) {
-		return Collections.singletonList(this.underlyingDim);
+	public ImList<LayerDim> getUnderlyingDimsByPosition(final long position) {
+		return ImCollections.newList(this.underlyingDim);
 	}
 	
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/LabelStack.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LabelStack.java
index 04711751..8dbf29ea 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/LabelStack.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LabelStack.java
@@ -11,12 +11,16 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
 import java.util.ArrayList;
 import java.util.List;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+
+@NonNullByDefault
 public class LabelStack {
 	
 	
@@ -30,12 +34,6 @@ public class LabelStack {
 		this.labels.add(label);
 	}
 	
-	public LabelStack(final String... labels) {
-		for (final String label : labels) {
-			this.labels.add(label);
-		}
-	}
-	
 	
 	/**
 	 * Adds a label to the bottom of the label stack.
@@ -82,15 +80,15 @@ public class LabelStack {
 	}
 	
 	@Override
-	public boolean equals(final Object obj) {
+	public boolean equals(final @Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}
-		if (!(obj instanceof LabelStack)) {
-			return false;
+		if (obj instanceof LabelStack) {
+			final LabelStack other= (LabelStack)obj;
+			return this.labels.equals(other.labels);
 		}
-		final LabelStack other= (LabelStack) obj;
-		return this.labels.equals(other.labels);
+		return false;
 	}
 	
 	@Override
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ILayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/Layer.java
index b6a2b709..d75c0000 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ILayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/Layer.java
@@ -11,21 +11,20 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
 import java.util.Properties;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.config.ConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
-import org.eclipse.statet.ecommons.waltable.layer.event.IVisualChangeEvent;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
-import org.eclipse.statet.ecommons.waltable.ui.IClientAreaProvider;
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.VisualChangeEvent;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 
 
@@ -69,10 +68,9 @@ import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
  *   <tr><td>corner</td><td>column header</td></tr>
  *   <tr><td>row header</td><td>body</td></tr>
  * </table>
- * 
- * @see CompositeLayer
  */
-public interface ILayer extends ILayerListener, IPersistable {
+@NonNullByDefault
+public interface Layer extends LayerListener, Persistable {
 	
 	
 	// Dispose
@@ -87,7 +85,7 @@ public interface ILayer extends ILayerListener, IPersistable {
 	 * 
 	 * @return the layer dimension
 	 */
-	ILayerDim getDim(/*@NonNull*/ Orientation orientation);
+	LayerDim getDim(Orientation orientation);
 	
 	
 	// Persistence
@@ -97,9 +95,9 @@ public interface ILayer extends ILayerListener, IPersistable {
 	 * {@link Properties} instance when the layer is persisted.
 	 * @param persistable the persistable to be registered
 	 */
-	void registerPersistable(IPersistable persistable);
+	void registerPersistable(Persistable persistable);
 	
-	void unregisterPersistable(IPersistable persistable);
+	void unregisterPersistable(Persistable persistable);
 	
 	// Configuration
 	
@@ -130,17 +128,14 @@ public interface ILayer extends ILayerListener, IPersistable {
 	 * is not interested in the command it should allow the command to keep traveling
 	 * down the stack.
 	 *
-	 * Note: Before the layer can process a command it <i>must</i> convert the
-	 * command to its local co-ordinates using {@link ILayerCommand#convertToTargetLayer(ILayer)}
-	 *
 	 * @param command the command to perform
 	 * @return true if the command has been handled, false otherwise
 	 */
-	boolean doCommand(ILayerCommand command);
+	boolean doCommand(LayerCommand command);
 	
-	void registerCommandHandler(ILayerCommandHandler<?> commandHandler);
+	void registerCommandHandler(LayerCommandHandler<?> commandHandler);
 	
-	void unregisterCommandHandler(Class<? extends ILayerCommand> commandClass);
+	void unregisterCommandHandler(Class<? extends LayerCommand> commandClass);
 	
 	// Events
 	
@@ -148,26 +143,25 @@ public interface ILayer extends ILayerListener, IPersistable {
 	 * Events can be fired to notify other components of the grid.
 	 * Events travel <i>up</i> the layer stack and may cause a repaint.
 	 * <p>
-	 * Example: When the contents of the grid change {@link IVisualChangeEvent} can be
+	 * Example: When the contents of the grid change {@link VisualChangeEvent} can be
 	 * fired to notify other layers to refresh their caches etc.
 	 * 
 	 * @param event the event to fire
 	 */
-	void fireLayerEvent(ILayerEvent event);
+	void fireLayerEvent(LayerEvent event);
 	
-	void addLayerListener(ILayerListener listener);
+	void addLayerListener(LayerListener listener);
 	
-	void removeLayerListener(ILayerListener listener);
+	void removeLayerListener(LayerListener listener);
 	
-	ILayerPainter getLayerPainter();
+	LayerPainter getLayerPainter();
 	
 	// Client area
 	
-	IClientAreaProvider getClientAreaProvider();
+	ClientAreaProvider getClientAreaProvider();
 	
-	void setClientAreaProvider(IClientAreaProvider clientAreaProvider);
+	void setClientAreaProvider(ClientAreaProvider clientAreaProvider);
 	
-	// Horizontal features
 	
 	// Columns
 	
@@ -185,9 +179,6 @@ public interface ILayer extends ILayerListener, IPersistable {
 	
 	long getColumnPositionByX(long x);
 	
-	// X
-	
-	// Vertical features
 	
 	// Rows
 	
@@ -205,12 +196,11 @@ public interface ILayer extends ILayerListener, IPersistable {
 	
 	long getRowPositionByY(long y);
 	
-	// Y
 	
-	// Cell features
+	// Cells
 	
-	ILayerCell getCellByPosition(long columnPosition, long rowPosition);
+	LayerCell getCellByPosition(long columnPosition, long rowPosition);
 	
-	ILayer getUnderlyingLayerByPosition(long columnPosition, long rowPosition);
+	@Nullable Layer getUnderlyingLayerByPosition(long columnPosition, long rowPosition);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ILayerCell.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerCell.java
index c27be959..9ae151c5 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ILayerCell.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerCell.java
@@ -11,23 +11,25 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer.cell;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
 
-public interface ILayerCell {
+
+@NonNullByDefault
+public interface LayerCell {
 	
 	
-	ILayer getLayer();
+	Layer getLayer();
 	
-	ILayerCellDim getDim(Orientation orientation);
+	LayerCellDim getDim(Orientation orientation);
 	
 	
 	long getOriginColumnPosition();
@@ -49,9 +51,9 @@ public interface ILayerCell {
 	
 	LRectangle getBounds();
 	
-	LabelStack getConfigLabels();
+	LabelStack getLabels();
 	
 	
-	Object getDataValue(int flags, IProgressMonitor monitor);
+	@Nullable Object getDataValue(int flags, @Nullable IProgressMonitor monitor);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ILayerCellDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerCellDim.java
index 12006040..28dac820 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ILayerCellDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerCellDim.java
@@ -12,12 +12,15 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer.cell;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
 
-public interface ILayerCellDim {
+
+@NonNullByDefault
+public interface LayerCellDim {
 	
 	
 	Orientation getOrientation();
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ICellPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerCellPainter.java
index 1c2db90f..6ae06979 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ICellPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerCellPainter.java
@@ -11,27 +11,27 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.painter.cell;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.painter.cell.PercentageBarCellPainter;
 
 
 /**
  * Implementations are responsible for painting a cell.
  * 
- * Custom {@link ICellPainter} can be registered in the {@link IConfigRegistry}.
+ * Custom {@link LayerCellPainter} can be registered in the {@link ConfigRegistry}.
  * This is a mechanism for plugging in custom cell painting.
  * 
  * @see PercentageBarCellPainter
  */
-public interface ICellPainter {
+public interface LayerCellPainter {
 	
 	
-	void paintCell(ILayerCell cell, GC gc, LRectangle bounds, IConfigRegistry configRegistry);
+	void paintCell(LayerCell cell, GC gc, LRectangle bounds, ConfigRegistry configRegistry);
 	
 	/**
 	 * Get the preferred width of the cell when rendered by this painter. Used for auto-resize.
@@ -40,7 +40,7 @@ public interface ICellPainter {
 	 * @param configRegistry
 	 * @return
 	 */
-	long getPreferredWidth(ILayerCell cell, GC gc, IConfigRegistry configRegistry);
+	long getPreferredWidth(LayerCell cell, GC gc, ConfigRegistry configRegistry);
 	
 	/**
 	 * Get the preferred height of the cell when rendered by this painter. Used for auto-resize.
@@ -49,9 +49,10 @@ public interface ICellPainter {
 	 * @param configRegistry
 	 * @return
 	 */
-	long getPreferredHeight(ILayerCell cell, GC gc, IConfigRegistry configRegistry);
+	long getPreferredHeight(LayerCell cell, GC gc, ConfigRegistry configRegistry);
 	
-	ICellPainter getCellPainterAt(long x, long y, ILayerCell cell, GC gc,
-			LRectangle adjustedCellBounds, IConfigRegistry configRegistrys);
+	
+	LayerCellPainter getCellPainterAt(long x, long y, LayerCell cell, GC gc,
+			LRectangle adjustedCellBounds, ConfigRegistry configRegistrys);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ILayerDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerDim.java
index 3cb4ed55..d345a2b5 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ILayerDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerDim.java
@@ -12,22 +12,27 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
 import java.util.Collection;
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
 
 
 /**
- * This interface for layers allows to write code which is independent of the orientation
- * (horizontal= columns / vertical= rows).
+ * A LayerDim represents one dimension (horizontal= columns / vertical= rows) of a layer.
+ * This allows to write code which is independent of the orientation.
  * 
  * It is recommend that implementation extends {@link AbstractLayerDim}.
  */
-public interface ILayerDim {
+@NonNullByDefault
+public interface LayerDim {
 	
 	
 	long POSITION_NA= Long.MIN_VALUE;
@@ -38,7 +43,7 @@ public interface ILayerDim {
 	 * 
 	 * @return the layer
 	 */
-	ILayer getLayer();
+	Layer getLayer();
 	
 	/**
 	 * Returns the orientation of this dimension.
@@ -74,8 +79,8 @@ public interface ILayerDim {
 	/**
 	 * Returns the number of positions in this layer dimension.
 	 * 
-	 * {@link ILayer#getColumnCount()} /
-	 * {@link ILayer#getRowCount()}
+	 * {@link Layer#getColumnCount()} /
+	 * {@link Layer#getRowCount()}
 	 * 
 	 * @return the count of local positions
 	 */
@@ -101,21 +106,21 @@ public interface ILayerDim {
 	 * 
 	 * @return the local position
 	 */
-	long underlyingToLocalPosition(ILayerDim sourceUnderlyingDim, long underlyingPosition);
+	long underlyingToLocalPosition(LayerDim sourceUnderlyingDim, long underlyingPosition);
 	
 	/**
 	 * Converts the specified positions in the specified underlying layer to the position in this
 	 * layer dimension.
 	 * 
-	 * {@link ILayer#underlyingToLocalColumnPositions(ILayer, Collection)} /
-	 * {@link ILayer#underlyingToLocalRowPositions(ILayer, Collection)}
+	 * {@link Layer#underlyingToLocalColumnPositions(Layer, Collection)} /
+	 * {@link Layer#underlyingToLocalRowPositions(Layer, Collection)}
 	 * 
 	 * @param sourceUnderlyingDim the underlying layer dimension the positions refers to
 	 * @param underlyingPositions the positions in the underlying layer
 	 * 
 	 * @return the local positions
 	 */
-	List<LRange> underlyingToLocalPositions(ILayerDim sourceUnderlyingDim,
+	List<LRange> underlyingToLocalPositions(LayerDim sourceUnderlyingDim,
 			Collection<LRange> underlyingPositions);
 	
 	/**
@@ -125,7 +130,7 @@ public interface ILayerDim {
 	 * 
 	 * @return the underlying layer dimensions
 	 */
-	List<ILayerDim> getUnderlyingDimsByPosition(long position);
+	@Nullable ImList<LayerDim> getUnderlyingDimsByPosition(long position);
 	
 	
 	// Pixel= X / Y, Width / Height
@@ -133,8 +138,8 @@ public interface ILayerDim {
 	/**
 	 * Returns the size of this layer dimension.
 	 * 
-	 * {@link ILayer#getWidth()} /
-	 * {@link ILayer#getHeight()}
+	 * {@link Layer#getWidth()} /
+	 * {@link Layer#getHeight()}
 	 * 
 	 * @return the size in pixel
 	 */
@@ -150,8 +155,8 @@ public interface ILayerDim {
 	/**
 	 * Returns the position in this layer dimension for the specified pixel coordinate.
 	 * 
-	 * {@link ILayer#getColumnPositionByX(int)} /
-	 * {@link ILayer#getRowPositionByY(int)}
+	 * {@link Layer#getColumnPositionByX(int)} /
+	 * {@link Layer#getRowPositionByY(int)}
 	 * 
 	 * @param pixel the pixel coordinate
 	 * 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerEvent.java
new file mode 100644
index 00000000..72bfc043
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerEvent.java
@@ -0,0 +1,36 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+
+
+/**
+ * A event fired by the {@link LayerCommandHandler} classes (usually to signal
+ * to handling of a {@link LayerCommand}).
+ * 
+ * <p>Layers can react to an event in {@link Layer#handleLayerEvent(LayerEvent)},
+ * other can listen to events by adding a {@link LayerListener} to a layer.</p>
+ */
+@NonNullByDefault
+public interface LayerEvent {
+	
+	
+	@Nullable LayerEvent toLayer(Layer targetLayer);
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ILayerListener.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerListener.java
index 40ce6f34..9d84fa3f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ILayerListener.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerListener.java
@@ -11,21 +11,22 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 
 /**
- * Object interested in receiving events related to a {@link ILayer}.
+ * Object interested in receiving events related to a {@link Layer}.
  */
-public interface ILayerListener {
+@NonNullByDefault
+public interface LayerListener {
 	
 	
 	/**
-	 * Handle an event notification from an {@link ILayer}
+	 * Handle an event notification from an {@link Layer}
 	 * @param event the event
 	 */
-	public void handleLayerEvent(ILayerEvent event);
+	void handleLayerEvent(LayerEvent event);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/ILayerPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerPainter.java
index 291d2dc1..e1573bd0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/ILayerPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerPainter.java
@@ -1,31 +1,42 @@
 /*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # Copyright (c) 2021 Stephan Wahlbrink and others.
  # 
  # This program and the accompanying materials are made available under the
  # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
  # 
- # SPDX-License-Identifier: EPL-2.0
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
  # 
  # Contributors:
- #     Original NatTable authors and others - initial API and implementation
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.painter.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
 import org.eclipse.swt.graphics.Device;
 import org.eclipse.swt.graphics.GC;
+import org.eclipse.swt.graphics.Rectangle;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
 
 
 /**
  * Classes implementing this interface are responsible for painting to the relevant {@link Device}.
  * Every layer has a layer painter. A layer can contribute to painting by providing its own painter.
  */
-public interface ILayerPainter {
+@NonNullByDefault
+public interface LayerPainter {
+	
+	
+	/**
+	 * This method is used to adjust the cell bounds when painting the layer. This is most often used to reduce the size
+	 * of the cell to accommodate grid lines. 
+	 */
+	LRectangle adjustCellBounds(long columnPosition, long rowPosition, LRectangle cellBounds);
 	
 	/**
 	 * @param natLayer
@@ -35,12 +46,7 @@ public interface ILayerPainter {
 	 * @param rectangle area the layer can paint in
 	 * @param configuration in use by NatTable. Useful for looking up associated painters.
 	 */
-	public void paintLayer(ILayer natLayer, GC gc, int xOffset, int yOffset, org.eclipse.swt.graphics.Rectangle rectangle, IConfigRegistry configuration);
-	
-	/**
-	 * This method is used to adjust the cell bounds when painting the layer. This is most often used to reduce the size
-	 * of the cell to accommodate grid lines. 
-	 */
-	public LRectangle adjustCellBounds(long columnPosition, long rowPosition, LRectangle cellBounds);
+	void paintLayer(Layer natLayer, GC gc, int xOffset, int yOffset,
+			Rectangle rectangle, ConfigRegistry configuration);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/LayerUtil.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerUtils.java
index 9eb3e135..604da000 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/LayerUtil.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/LayerUtils.java
@@ -11,15 +11,18 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
 
-public class LayerUtil {
+
+@NonNullByDefault
+public class LayerUtils {
 	
 	
 	/**
@@ -29,9 +32,9 @@ public class LayerUtil {
 	 * @param targetLayer layer to convert the from position to 
 	 * @return converted position, or ILayerDim.POSITION_NA if conversion not possible
 	 */
-	public static final long convertPosition(final ILayerDim sourceDim,
+	public static final long convertPosition(final LayerDim sourceDim,
 			final long sourceRefPosition, final long sourcePosition,
-			final ILayerDim targetDim) {
+			final LayerDim targetDim) {
 		if (targetDim == sourceDim) {
 			return sourcePosition;
 		}
@@ -41,7 +44,7 @@ public class LayerUtil {
 			return targetDim.getPositionById(id);
 		}
 		catch (final PositionOutOfBoundsException e) {
-			return ILayerDim.POSITION_NA;
+			return LayerDim.POSITION_NA;
 		}
 	}
 	
@@ -52,8 +55,8 @@ public class LayerUtil {
 	 * @param targetLayer layer to convert the from position to 
 	 * @return converted column position, or -1 if conversion not possible
 	 */
-	public static final long convertColumnPosition(final ILayer sourceLayer,
-			final long sourceColumnPosition, final ILayer targetLayer) {
+	public static final long convertColumnPosition(final Layer sourceLayer,
+			final long sourceColumnPosition, final Layer targetLayer) {
 		return convertPosition(sourceLayer.getDim(HORIZONTAL),
 				sourceColumnPosition, sourceColumnPosition,
 				targetLayer.getDim(HORIZONTAL) );
@@ -66,8 +69,8 @@ public class LayerUtil {
 	 * @param targetLayer layer to convert the from position to 
 	 * @return converted row position, or -1 if conversion not possible
 	 */
-	public static final long convertRowPosition(final ILayer sourceLayer,
-			final long sourceRowPosition, final ILayer targetLayer) {
+	public static final long convertRowPosition(final Layer sourceLayer,
+			final long sourceRowPosition, final Layer targetLayer) {
 		return convertPosition(sourceLayer.getDim(VERTICAL),
 				sourceRowPosition, sourceRowPosition,
 				targetLayer.getDim(VERTICAL) );
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/TransformLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/TransformLayer.java
index 1f45679b..e1b11d22 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/TransformLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/TransformLayer.java
@@ -11,14 +11,13 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCellDim;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCellDim;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
 
 /**
@@ -30,21 +29,24 @@ import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCellDim;
  * 
  * The layer is similar to {@link AbstractLayerTransform}, but is {@link DimBasedLayer dim-based}.
  */
-public abstract class TransformLayer extends ForwardLayer {
+@NonNullByDefault
+public abstract class TransformLayer<TLayerDim extends ForwardLayerDim<? extends TransformLayer<TLayerDim>>>
+		extends ForwardLayer<TLayerDim> {
 	
 	
-	public TransformLayer(/*@NonNull*/ final ILayer underlyingLayer) {
-		super(underlyingLayer);
+	public TransformLayer(final Layer underlyingLayer,
+			final @Nullable LayerPainter layerPainter) {
+		super(underlyingLayer, layerPainter);
 	}
 	
-	
-	@Override
-	protected abstract void initDims();
+	public TransformLayer(final Layer underlyingLayer) {
+		this(underlyingLayer, null);
+	}
 	
 	
 	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
-		final ILayerCell underlyingCell= getUnderlyingLayer().getCellByPosition(
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+		final LayerCell underlyingCell= getUnderlyingLayer().getCellByPosition(
 				getDim(HORIZONTAL).localToUnderlyingPosition(columnPosition, columnPosition),
 				getDim(VERTICAL).localToUnderlyingPosition(rowPosition, rowPosition) );
 		
@@ -54,14 +56,14 @@ public abstract class TransformLayer extends ForwardLayer {
 				underlyingCell );
 	}
 	
-	protected ILayerCellDim transformCellDim(final ILayerCellDim underlyingDim, final long position) {
+	protected LayerCellDim transformCellDim(final LayerCellDim underlyingDim, final long position) {
 		if (underlyingDim.getPosition() == position) {
 			return underlyingDim;
 		}
 		
 		final long originPosition= position -
 				(underlyingDim.getPosition() - underlyingDim.getOriginPosition());
-		return new LayerCellDim(underlyingDim.getOrientation(), underlyingDim.getId(),
+		return new BasicLayerCellDim(underlyingDim.getOrientation(), underlyingDim.getId(),
 				position, originPosition, underlyingDim.getPositionSpan() );
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/TransformLayerDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/TransformLayerDim.java
index d8a029b8..68808a55 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/TransformLayerDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/TransformLayerDim.java
@@ -12,31 +12,34 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.core.layer;
 
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.coordinate.PixelOutOfBoundsException;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PixelOutOfBoundsException;
 
 
 /**
- * Dim implementation for {@link TransformLayer}.
+ * A layer dimension for a {@link TransformLayer}.
  * 
- * @param <T> the type of the layer
+ * @param <TLayer> the type of the layer
  */
-public abstract class TransformLayerDim<T extends ILayer> extends ForwardLayerDim<T> {
+@NonNullByDefault
+public abstract class TransformLayerDim<TLayer extends Layer> extends ForwardLayerDim<TLayer> {
 	
 	
-	public TransformLayerDim(/*@NonNull*/ final T layer, /*@NonNull*/ final ILayerDim underlyingDim) {
+	public TransformLayerDim(final TLayer layer, final LayerDim underlyingDim) {
 		super(layer, underlyingDim.getOrientation(), underlyingDim);
 	}
 	
-	public TransformLayerDim(/*@NonNull*/ final T layer, /*@NonNull*/ final Orientation orientation,
-			/*@NonNull*/ final ILayerDim underlyingDim) {
+	public TransformLayerDim(final TLayer layer, final Orientation orientation,
+			final LayerDim underlyingDim) {
 		super(layer, orientation, underlyingDim);
 	}
 	
@@ -68,7 +71,7 @@ public abstract class TransformLayerDim<T extends ILayer> extends ForwardLayerDi
 	public abstract long localToUnderlyingPosition(final long refPosition, final long position);
 	
 	@Override
-	public long underlyingToLocalPosition(final ILayerDim sourceUnderlyingDim,
+	public long underlyingToLocalPosition(final LayerDim sourceUnderlyingDim,
 			final long underlyingPosition) {
 		if (sourceUnderlyingDim != this.underlyingDim) {
 			throw new IllegalArgumentException("underlyingLayer"); //$NON-NLS-1$
@@ -78,7 +81,7 @@ public abstract class TransformLayerDim<T extends ILayer> extends ForwardLayerDi
 	}
 	
 	@Override
-	public List<LRange> underlyingToLocalPositions(final ILayerDim sourceUnderlyingDim,
+	public List<LRange> underlyingToLocalPositions(final LayerDim sourceUnderlyingDim,
 			final Collection<LRange> underlyingPositions) {
 		if (sourceUnderlyingDim != this.underlyingDim) {
 			throw new IllegalArgumentException("underlyingLayer"); //$NON-NLS-1$
@@ -109,7 +112,7 @@ public abstract class TransformLayerDim<T extends ILayer> extends ForwardLayerDi
 	public long getPositionByPixel(final long pixel) {
 		final long position= doUnderlyingToLocalPosition(this.underlyingDim.getPositionByPixel(pixel));
 		if (position < 0 || position >= getPositionCount()) {
-			throw PixelOutOfBoundsException.pixel(pixel, getOrientation());
+			throw new PixelOutOfBoundsException(pixel, getOrientation());
 		}
 		return position;
 	}
@@ -119,7 +122,7 @@ public abstract class TransformLayerDim<T extends ILayer> extends ForwardLayerDi
 		final long underlyingRefPosition= localToUnderlyingPosition(refPosition, refPosition);
 		return this.underlyingDim.getPositionStart(underlyingRefPosition,
 				(refPosition == position) ?
-						underlyingRefPosition : 
+						underlyingRefPosition :
 						localToUnderlyingPosition(refPosition, position) );
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/CellVisualChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/CellVisualChangeEvent.java
new file mode 100644
index 00000000..64afbf2a
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/CellVisualChangeEvent.java
@@ -0,0 +1,95 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer.events;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+
+
+@NonNullByDefault
+public class CellVisualChangeEvent implements VisualChangeEvent {
+	
+	
+	protected final Layer layer;
+	
+	protected final LPoint position;
+	
+	
+	public CellVisualChangeEvent(final Layer layer, final LPoint position) {
+		this.layer= layer;
+		this.position= position;
+	}
+	
+	public CellVisualChangeEvent(final Layer layer, final long columnPosition, final long rowPosition) {
+		this(layer, new LPoint(columnPosition, rowPosition));
+	}
+	
+	@Override
+	public @Nullable CellVisualChangeEvent toLayer(final Layer targetLayer) {
+		if (targetLayer == this.layer) {
+			return this;
+		}
+		
+		final var hTargetDim= targetLayer.getDim(HORIZONTAL);
+		final var vTargetDim= targetLayer.getDim(VERTICAL);
+		final long hPosition= hTargetDim.underlyingToLocalPosition(this.layer.getDim(HORIZONTAL),
+				this.position.x );
+		final long vPosition= vTargetDim.underlyingToLocalPosition(this.layer.getDim(VERTICAL),
+				this.position.y );
+		
+		return (hPosition >= 0 && hPosition < hTargetDim.getPositionCount()
+						&& vPosition >= 0 && vPosition < vTargetDim.getPositionCount() ) ?
+				toLayer(targetLayer, hPosition, vPosition) :
+				null;
+	}
+	
+	protected @Nullable CellVisualChangeEvent toLayer(final Layer targetLayer,
+			final long columnPosition, final long rowPosition) {
+		return new CellVisualChangeEvent(targetLayer, columnPosition, rowPosition);
+	}
+	
+	
+	@Override
+	public final Layer getLayer() {
+		return this.layer;
+	}
+	
+	public LPoint getPosition() {
+		return this.position;
+	}
+	
+	public long getColumnPosition() {
+		return this.position.x;
+	}
+	
+	public long getRowPosition() {
+		return this.position.y;
+	}
+	
+	@Override
+	public ImList<LRectangle> getChangedPositionRectangles() {
+		return ImCollections.newList(
+				new LRectangle(this.position.x, this.position.y, 1, 1) );
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/DimGeneralStrucuralChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/DimGeneralStrucuralChangeEvent.java
new file mode 100644
index 00000000..edf5a77b
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/DimGeneralStrucuralChangeEvent.java
@@ -0,0 +1,83 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer.events;
+
+import java.util.List;
+
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+
+
+@NonNullByDefault
+public class DimGeneralStrucuralChangeEvent implements VisualChangeEvent, StructuralChangeEvent {
+	
+	
+	private final LayerDim layerDim;
+	
+	
+	public DimGeneralStrucuralChangeEvent(final LayerDim layerDim) {
+		this.layerDim= layerDim;
+	}
+	
+	@Override
+	public @Nullable DimGeneralStrucuralChangeEvent toLayer(final Layer targetLayer) {
+		final LayerDim targetLayerDim= targetLayer.getDim(this.layerDim.getOrientation());
+		if (targetLayerDim == this.layerDim) {
+			return this;
+		}
+		
+		return new DimGeneralStrucuralChangeEvent(targetLayerDim);
+	}
+	
+	
+	public final LayerDim getLayerDim() {
+		return this.layerDim;
+	}
+	
+	public final Orientation getOrientation() {
+		return this.layerDim.getOrientation();
+	}
+	
+	@Override
+	public final Layer getLayer() {
+		return this.layerDim.getLayer();
+	}
+	
+	
+	@Override
+	public ImList<LRectangle> getChangedPositionRectangles() {
+		final var layer= getLayer();
+		return ImCollections.newList(
+				new LRectangle(0, 0, layer.getColumnCount(), layer.getRowCount()) );
+	}
+	
+	
+	@Override
+	public boolean isStructureChanged(final Orientation orientation) {
+		return (getOrientation() == orientation);
+	}
+	
+	@Override
+	public @Nullable List<StructuralDiff> getDiffs(final Orientation orientation) {
+		return null;
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/DimPositionsStructuralChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/DimPositionsStructuralChangeEvent.java
new file mode 100644
index 00000000..4c70a170
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/DimPositionsStructuralChangeEvent.java
@@ -0,0 +1,58 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer.events;
+
+import java.util.List;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+
+
+/**
+ * Event indicating a change in the structure of the columns/rows.
+ * 
+ * <p>This event carried {@link StructuralDiff} indicating the columns/rows
+ * which have changed.</p>
+ */
+@NonNullByDefault
+public abstract class DimPositionsStructuralChangeEvent extends DimPositionsVisualChangeEvent
+		implements StructuralChangeEvent {
+	
+	
+	/**
+	 * Creates a new ColumnStructuralChangeEvent based on the given information.
+	 * @param layerDim the layer dim to which the given positions match.
+	 * @param positions the position ranges of columns/rows that have changed.
+	 */
+	public DimPositionsStructuralChangeEvent(final LayerDim layerDim,
+			final List<LRange> positions) {
+		super(layerDim, positions);
+	}
+	
+	@Override
+	protected @Nullable abstract DimPositionsStructuralChangeEvent toLayer(LayerDim targetLayerDim,
+			List<LRange> positions);
+	
+	
+	@Override
+	public boolean isStructureChanged(final Orientation orientation) {
+		return (getOrientation() == orientation);
+	}
+	
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/DimPositionsVisualChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/DimPositionsVisualChangeEvent.java
new file mode 100644
index 00000000..1cd6a559
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/DimPositionsVisualChangeEvent.java
@@ -0,0 +1,144 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer.events;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import java.util.List;
+
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNull;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+
+
+/**
+ * An event that indicates a visible change to one ore more columns/rows in the
+ * layer.
+ */
+@NonNullByDefault
+public class DimPositionsVisualChangeEvent implements VisualChangeEvent {
+	
+	
+	/**
+	 * The LayerDim to which the given column/row positions match
+	 */
+	private final LayerDim layerDim;
+	
+	/**
+	 * The column position ranges for the columns/rows that have changed.
+	 */
+	private final List<LRange> positions;
+	
+	
+	/**
+	 * Creates a new ColumnVisualChangeEvent based on the given information.
+	 * @param layerDim the layer dim to which the given positions match.
+	 * @param positions the position ranges of columns/rows that have changed.
+	 */
+	public DimPositionsVisualChangeEvent(final LayerDim layerDim, final List<LRange> positions) {
+		this.layerDim= layerDim;
+		this.positions= positions;
+	}
+	
+	public DimPositionsVisualChangeEvent(final LayerDim layerDim, final LRange positionRanges) {
+		this.layerDim= layerDim;
+		this.positions= ImCollections.newList(positionRanges);
+	}
+	
+	@Override
+	public @Nullable DimPositionsVisualChangeEvent toLayer(final Layer targetLayer) {
+		final LayerDim targetLayerDim= targetLayer.getDim(getOrientation());
+		if (targetLayerDim == this.layerDim) {
+			return this;
+		}
+		
+		final var positionRanges= targetLayerDim.underlyingToLocalPositions(this.layerDim,
+				this.positions );
+		
+		return (positionRanges != null && positionRanges.size() > 0) ?
+				toLayer(targetLayerDim, positionRanges) : null;
+	}
+	
+	protected @Nullable DimPositionsVisualChangeEvent toLayer(final LayerDim targetLayerDim,
+			final List<LRange> positionRanges) {
+		return new DimPositionsVisualChangeEvent(targetLayerDim, positionRanges);
+	}
+	
+	
+	public final LayerDim getLayerDim() {
+		return this.layerDim;
+	}
+	
+	public final Orientation getOrientation() {
+		return this.layerDim.getOrientation();
+	}
+	
+	@Override
+	public final Layer getLayer() {
+		return this.layerDim.getLayer();
+	}
+	
+	/**
+	 * @return The column/row position ranges for the columns that have changed.
+	 */
+	public List<LRange> getPositionRanges() {
+		return this.positions;
+	}
+	
+	@Override
+	public ImList<LRectangle> getChangedPositionRectangles() {
+		final var columnPositionRanges= getPositionRanges();
+		final var positionRectangles= new @NonNull LRectangle[columnPositionRanges.size()];
+		
+		final long positionCount;
+		switch (getOrientation()) {
+		case HORIZONTAL:
+			positionCount= getLayer().getDim(VERTICAL).getPositionCount();
+			for (int i= 0; i < positionRectangles.length; i++) {
+				final var range= columnPositionRanges.get(i);
+				positionRectangles[i]=
+						new LRectangle(range.start, 0, range.end - range.start, positionCount);
+			}
+			break;
+		case VERTICAL:
+			positionCount= getLayer().getDim(HORIZONTAL).getPositionCount();
+			for (int i= 0; i < positionRectangles.length; i++) {
+				final var range= columnPositionRanges.get(i);
+				positionRectangles[i]=
+						new LRectangle(0, range.start, positionCount, range.end - range.start);
+			}
+			break;
+		default:
+			throw new IllegalStateException();
+		}
+		
+		return ImCollections.newList(positionRectangles);
+	}
+	
+	
+	@Override
+	public String toString() {
+		return getClass().getSimpleName();
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/GeneralStructuralChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/GeneralStructuralChangeEvent.java
new file mode 100644
index 00000000..7e714e10
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/GeneralStructuralChangeEvent.java
@@ -0,0 +1,55 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer.events;
+
+import java.util.List;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+
+
+/**
+ * General event indicating that structures cached by the layers need refreshing.
+ * <p>
+ * TIP: Consider throwing a more focused event (subclass) if you need to do this.
+ */
+@NonNullByDefault
+public class GeneralStructuralChangeEvent extends GeneralVisualChangeEvent implements StructuralChangeEvent {
+	
+	
+	public GeneralStructuralChangeEvent(final Layer layer) {
+		super(layer);
+	}
+	
+	@Override
+	public @Nullable GeneralStructuralChangeEvent toLayer(final Layer targetLayer) {
+		return new GeneralStructuralChangeEvent(targetLayer);
+	}
+	
+	
+	@Override
+	public boolean isStructureChanged(final Orientation orientation) {
+		return true;
+	}
+	
+	@Override
+	public @Nullable List<StructuralDiff> getDiffs(final Orientation orientation) {
+		return null;
+	}
+	
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/GeneralVisualChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/GeneralVisualChangeEvent.java
new file mode 100644
index 00000000..525cbd2f
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/GeneralVisualChangeEvent.java
@@ -0,0 +1,58 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer.events;
+
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+
+
+@NonNullByDefault
+public class GeneralVisualChangeEvent implements VisualChangeEvent {
+	
+	
+	private final Layer layer;
+	
+	
+	public GeneralVisualChangeEvent(final Layer layer) {
+		this.layer= layer;
+	}
+	
+	@Override
+	public @Nullable GeneralVisualChangeEvent toLayer(final Layer targetLayer) {
+		if (targetLayer == this.layer) {
+			return this;
+		}
+		
+		return new GeneralVisualChangeEvent(targetLayer);
+	}
+	
+	
+	@Override
+	public Layer getLayer() {
+		return this.layer;
+	}
+	
+	
+	@Override
+	public ImList<LRectangle> getChangedPositionRectangles() {
+		return ImCollections.newList(
+				new LRectangle(0, 0, this.layer.getColumnCount(), this.layer.getRowCount()) );
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/IStructuralChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/StructuralChangeEvent.java
index 4fdb2b78..74e1ff0d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/IStructuralChangeEvent.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/StructuralChangeEvent.java
@@ -11,9 +11,14 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer.event;
+package org.eclipse.statet.ecommons.waltable.core.layer.events;
 
-import java.util.Collection;
+import java.util.List;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
 
 
 /**
@@ -21,14 +26,12 @@ import java.util.Collection;
  * defined as something that modifies the number of columns/rows in the layer or
  * their associated widths/heights.
  */
-public interface IStructuralChangeEvent extends IVisualChangeEvent {
-
-	public boolean isHorizontalStructureChanged();
+@NonNullByDefault
+public interface StructuralChangeEvent extends VisualChangeEvent {
 	
-	public Collection<StructuralDiff> getColumnDiffs();
 	
-	public boolean isVerticalStructureChanged();
+	boolean isStructureChanged(Orientation orientation);
 	
-	public Collection<StructuralDiff> getRowDiffs();
+	@Nullable List<StructuralDiff> getDiffs(Orientation orientation);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/StructuralDiff.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/StructuralDiff.java
index fb0a40f6..a1447c32 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/StructuralDiff.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/StructuralDiff.java
@@ -11,42 +11,38 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer.event;
+package org.eclipse.statet.ecommons.waltable.core.layer.events;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+
+
+@NonNullByDefault
 public class StructuralDiff {
 	
-	public enum DiffTypeEnum {
+	public enum DiffType {
 		ADD, CHANGE, DELETE;
 	}
 	
 	
-	private final DiffTypeEnum diffType;
+	private final DiffType diffType;
 	
 	private final LRange beforePositionRange;
 	
 	private final LRange afterPositionRange;
 	
 	
-	public StructuralDiff(final DiffTypeEnum diffType, final LRange beforePositionRange, final LRange afterPositionRange) {
-		if (diffType == null) {
-			throw new NullPointerException("diffType");
-		}
-		if (beforePositionRange == null) {
-			throw new NullPointerException("beforePositionRange");
-		}
-		if (afterPositionRange == null) {
-			throw new NullPointerException("afterPositionRange");
-		}
-		
-		this.diffType= diffType;
-		this.beforePositionRange= beforePositionRange;
-		this.afterPositionRange= afterPositionRange;
+	public StructuralDiff(final DiffType diffType, final LRange beforePositionRange, final LRange afterPositionRange) {
+		this.diffType= nonNullAssert(diffType);
+		this.beforePositionRange= nonNullAssert(beforePositionRange);
+		this.afterPositionRange= nonNullAssert(afterPositionRange);
 	}
 	
-	public DiffTypeEnum getDiffType() {
+	public DiffType getDiffType() {
 		return this.diffType;
 	}
 	
@@ -67,17 +63,17 @@ public class StructuralDiff {
 	}
 	
 	@Override
-	public boolean equals(final Object obj) {
+	public boolean equals(final @Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}
-		if (!(obj instanceof StructuralDiff)) {
-			return false;
+		if (obj instanceof StructuralDiff) {
+			final StructuralDiff other= (StructuralDiff)obj;
+			return (this.diffType == other.diffType
+					&& this.beforePositionRange == other.beforePositionRange
+					&& this.afterPositionRange == other.afterPositionRange );
 		}
-		final StructuralDiff other= (StructuralDiff) obj;
-		return (this.diffType == other.diffType
-				&& this.beforePositionRange == other.beforePositionRange
-				&& this.afterPositionRange == other.afterPositionRange );
+		return false;
 	}
 	
 	@Override
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/IVisualChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/VisualChangeEvent.java
index 0709fbcb..644348d7 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/IVisualChangeEvent.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/events/VisualChangeEvent.java
@@ -11,12 +11,15 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer.event;
+package org.eclipse.statet.ecommons.waltable.core.layer.events;
 
-import java.util.Collection;
+import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
 
 
 /**
@@ -25,18 +28,20 @@ import org.eclipse.statet.ecommons.waltable.layer.ILayer;
  * It does not imply a structural change to the layer. This means that cached
  * structure does not need to be invalidated due to visible change events.
  */
-public interface IVisualChangeEvent extends ILayerEvent {
-
+@NonNullByDefault
+public interface VisualChangeEvent extends LayerEvent {
+	
+	
 	/**
 	 * @return the layer that the visible change event is originating from.
 	 */
-	public ILayer getLayer();
+	Layer getLayer();
 	
 	/**
 	 * @return the position rectangles that have changed and need to be redrawn.
 	 * If no rectangles are returned, then the receiver should assume that the
 	 * entire layer is changed and will need to be redrawn.
 	 */
-	public Collection<LRectangle> getChangedPositionRectangles();
+	List<LRectangle> getChangedPositionRectangles();
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/IOverlayPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/top/OverlayPainter.java
index fe44e4be..81134d86 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/IOverlayPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/top/OverlayPainter.java
@@ -11,22 +11,25 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.painter;
+package org.eclipse.statet.ecommons.waltable.core.layer.top;
 
 import org.eclipse.swt.graphics.GC;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 /**
- * An overlay painter is given a chance to paint the canvas once
- * the layers have finished rendering.
+ * An overlay painter is given a chance to paint the canvas once the layers have finished rendering.
  * 
- *  @see NatTable#addOverlayPainter(IOverlayPainter)
+ * @see NatTable#addOverlayPainter(SwtOverlayPainter)
  */
-public interface IOverlayPainter {
-
-	public void paintOverlay(GC gc, ILayer layer);
+@NonNullByDefault
+public interface OverlayPainter {
+	
+	
+	void paintOverlay(GC gc, Layer layer);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/top/TopLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/top/TopLayer.java
new file mode 100644
index 00000000..9d2924ea
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/top/TopLayer.java
@@ -0,0 +1,30 @@
+/*=============================================================================#
+ # Copyright (c) 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer.top;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+
+
+@NonNullByDefault
+public interface TopLayer extends Layer {
+	
+	
+	@Override
+	TopLayerDim getDim(Orientation orientation);
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/top/TopLayerDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/top/TopLayerDim.java
new file mode 100644
index 00000000..817f8af5
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/layer/top/TopLayerDim.java
@@ -0,0 +1,35 @@
+/*=============================================================================#
+ # Copyright (c) 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.layer.top;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+
+
+@NonNullByDefault
+public interface TopLayerDim extends LayerDim {
+	
+	
+	@Override
+	TopLayer getLayer();
+	
+	
+	void repaintPosition(long position);
+	
+	void repaintPositions(LRange positions);
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/Style.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/BasicStyle.java
index f99d7f3f..a80e3122 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/Style.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/BasicStyle.java
@@ -11,41 +11,54 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.style;
+package org.eclipse.statet.ecommons.waltable.core.style;
 
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
-import java.util.Set;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
-public class Style implements IStyle {
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
 
-	private final Map<ConfigAttribute<?>, Object> styleAttributeValueMap= new HashMap<>();
 
+/**
+ * A style backed by a map.
+ */
+@NonNullByDefault
+public class BasicStyle implements Style {
+	
+	
+	private final Map<ConfigAttribute<?>, Object> configAttributeValueMap= new HashMap<>();
+	
+	
 	@Override
 	@SuppressWarnings("unchecked")
-	public <T> T getAttributeValue(final ConfigAttribute<T> styleAttribute) {
-		return (T) this.styleAttributeValueMap.get(styleAttribute);
+	public <T> T getAttributeValue(final ConfigAttribute<T> configAttribute) {
+		return (T)this.configAttributeValueMap.get(configAttribute);
 	}
-
+	
 	@Override
-	public <T> void setAttributeValue(final ConfigAttribute<T> styleAttribute, final T value) {
-		this.styleAttributeValueMap.put(styleAttribute, value);
+	public <T> void setAttributeValue(final ConfigAttribute<T> configAttribute, final @Nullable T value) {
+		if (value != null) {
+			this.configAttributeValueMap.put(configAttribute, value);
+		}
+		else {
+			this.configAttributeValueMap.remove(configAttribute);
+		}
 	}
-
+	
 	@Override
 	public String toString() {
 		final StringBuilder resultBuilder= new StringBuilder();
 		resultBuilder.append(this.getClass().getSimpleName() + ": "); //$NON-NLS-1$
-
-		final Set<Entry<ConfigAttribute<?>, Object>> entrySet= this.styleAttributeValueMap.entrySet();
-
-		for (final Entry<ConfigAttribute<?>, Object> entry : entrySet) {
+		
+		for (final Entry<ConfigAttribute<?>, Object> entry : this.configAttributeValueMap.entrySet()) {
 			resultBuilder.append(entry.getKey() + ": " + entry.getValue() + "\n"); //$NON-NLS-1$ //$NON-NLS-2$
 		}
-
+		
 		return resultBuilder.toString();
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/BorderStyle.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/BorderStyle.java
index 378973b9..8921d75a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/BorderStyle.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/BorderStyle.java
@@ -11,30 +11,36 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.style;
+package org.eclipse.statet.ecommons.waltable.core.style;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
 
 import org.eclipse.swt.graphics.Color;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
 import org.eclipse.statet.ecommons.waltable.persistence.ColorPersistor;
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
 /**
  * This class defines the visual attributes of a border:
  * 
  * <dl>
- * <dt>Thickness</dt>
+ *   <dt>Thickness</dt>
  *   <dd>The width of the border in pixel</dd>
- * <dt>Color</dt>
+ *   <dt>Color</dt>
  *   <dd>The color of the border</dd>
- * <dt>Line Style</dt>
+ *   <dt>Line Style</dt>
  *   <dd>The line style of the border, a constant of {@link LineStyle}</dd>
- * <dt>Offset</dt>
+ *   <dt>Offset</dt>
  *   <dd>The offset of the border toward the regular painting area.
- *       If not specified otherwise, the value is 0, meaning no offset.  A value &gt; 0 shifts the border inwards, a 
- *       value &lt; 0 shifts the border outwards. For example -1 can be used to paint the border over the grid.</dd>
+ *       If not specified otherwise, the value is 0, meaning no offset. A
+ *       value &gt; 0 shifts the border inwards, a value &lt; 0 shifts the
+ *       border outwards.</dd>
  * </dl> 
  */
+@NonNullByDefault
 public class BorderStyle {
 	
 	
@@ -48,28 +54,17 @@ public class BorderStyle {
 		
 		
 	}
-
-
-	private int thickness;
-
-	private Color color;
-
-	private LineStyle lineStyle;
-
-	private int offset;
-
-
-	/**
-	 * Creates a new border style to paint a thin, black, solid line.
-	 */
-	public BorderStyle() {
-		this(1, GUIHelper.COLOR_BLACK, LineStyle.SOLID, 0);
-	}
-
-	public BorderStyle(final int thickness, final Color color, final LineStyle lineStyle) {
-		this(thickness, color, lineStyle, 0);
-	}
-
+	
+	
+	private final int thickness;
+	
+	private final Color color;
+	
+	private final LineStyle lineStyle;
+	
+	private final int offset;
+	
+	
 	/**
 	 * Creates a new border style.
 	 * 
@@ -79,68 +74,48 @@ public class BorderStyle {
 	 * @param offset the offset of the border
 	 */
 	public BorderStyle(final int thickness, final Color color, final LineStyle lineStyle, final int offset) {
-		setThickness(thickness); 
-		setColor(color);
-		setLineStyle(lineStyle);
-		setOffset(offset);
+		this.thickness= (thickness > 0) ? thickness : 0;
+		this.color= nonNullAssert(color);
+		this.lineStyle= nonNullAssert(lineStyle);
+		this.offset= offset;
 	}
-
+	
+	public BorderStyle(final int thickness, final Color color, final LineStyle lineStyle) {
+		this(thickness, color, lineStyle, 0);
+	}
+	
 	/**
 	 * Reconstruct this instance from the persisted String.
 	 * 
 	 * @see BorderStyle#toString()
 	 */
 	public BorderStyle(final String string) {
-		final String[] tokens= string.split("\\|"); //$NON-NLS-1$
-
+		final var tokens= string.split("\\|"); //$NON-NLS-1$
+		
 		this.thickness= Integer.parseInt(tokens[0]);
 		this.color= ColorPersistor.asColor(tokens[1]);
 		this.lineStyle= LineStyle.valueOf(tokens[2]);
-		if (tokens.length > 3) {
-			this.offset= Integer.parseInt(tokens[3]);
-		}
+		this.offset= (tokens.length > 3) ? Integer.parseInt(tokens[3]) : 0;
 	}
-
-
+	
+	
 	public int getThickness() {
 		return this.thickness;
 	}
-
+	
 	public Color getColor() {
 		return this.color;
 	}
-
+	
 	public LineStyle getLineStyle() {
 		return this.lineStyle;
 	}
-
+	
 	public int getOffset() {
 		return this.offset;
 	}
-
-	public void setThickness(final int thickness) {
-		this.thickness= (thickness > 0) ? thickness : 0;
-	}
-
-	public void setColor(final Color color) {
-		if (color == null) {
-			throw new NullPointerException("color"); //$NON-NLS-1$
-		}
-		this.color= color;
-	}
-
-	public void setLineStyle(final LineStyle lineStyle) {
-		if (lineStyle == null) {
-			throw new NullPointerException("lineStyle"); //$NON-NLS-1$
-		}
-		this.lineStyle= lineStyle;
-	}
-
-	public void setOffset(final int offset) {
-		this.offset= offset;
-	}
-
-
+	
+	
 	@Override
 	public int hashCode() {
 		return ((this.thickness
@@ -150,21 +125,20 @@ public class BorderStyle {
 	}
 
 	@Override
-	public boolean equals(final Object obj) {
+	public boolean equals(final @Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}
-		if (!(obj instanceof BorderStyle)) {
-			return false;
+		if (obj instanceof BorderStyle) {
+			final BorderStyle other= (BorderStyle)obj;
+			return (this.thickness == other.thickness
+					&& this.color.equals(other.color)
+					&& this.lineStyle == other.lineStyle
+					&& this.offset == other.offset );
 		}
-
-		final BorderStyle that= (BorderStyle) obj;
-		return (this.thickness == that.thickness
-				&& this.color.equals(that.color)
-				&& this.lineStyle == that.lineStyle
-				&& this.offset == that.offset );
+		return false;
 	}
-
+	
 	/**
 	 * @return a human readable representation of the border style. This is
 	 *         suitable for constructing an equivalent instance using the
@@ -174,5 +148,5 @@ public class BorderStyle {
 	public String toString() {
 		return "" + this.thickness + '|' + ColorPersistor.asString(this.color) + '|' + this.lineStyle + '|' + this.offset; //$NON-NLS-1$
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/CellStyling.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/CellStyling.java
new file mode 100644
index 00000000..d95f8566
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/CellStyling.java
@@ -0,0 +1,98 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.style;
+
+import java.util.Set;
+
+import org.eclipse.swt.graphics.Color;
+import org.eclipse.swt.graphics.Font;
+import org.eclipse.swt.graphics.Image;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
+
+
+@NonNullByDefault
+public class CellStyling {
+	
+	/**
+	 * Attribute for configuring the background color of a cell.
+	 */
+	public static final ConfigAttribute<Color> BACKGROUND_COLOR= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the foreground color of a cell.
+	 */
+	public static final ConfigAttribute<Color> FOREGROUND_COLOR= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the gradient sweeping background color.
+	 * Is used by the GradientBackgroundPainter.
+	 */
+	public static final ConfigAttribute<Color> GRADIENT_BACKGROUND_COLOR= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the gradient sweeping foreground color.
+	 * Is used by the GradientBackgroundPainter.
+	 */
+	public static final ConfigAttribute<Color> GRADIENT_FOREGROUND_COLOR= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the horizontal alignment of a cell.
+	 */
+	public static final ConfigAttribute<HorizontalAlignment> HORIZONTAL_ALIGNMENT= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the vertical alignment of a cell.
+	 */
+	public static final ConfigAttribute<VerticalAlignment> VERTICAL_ALIGNMENT= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the font to be used on rendering text.
+	 * Is used by all specialisations of the AbstractTextPainter.
+	 */
+	public static final ConfigAttribute<Font> FONT= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the image to rendered.
+	 * Is used by the ImagePainter to determine the image to render dynamically.
+	 */
+	public static final ConfigAttribute<Image> IMAGE= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the border style.
+	 * Is used by the LineBorderDecorator.
+	 */
+	public static final ConfigAttribute<BorderStyle> BORDER_STYLE= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the echo character that should be used by PasswordTextPainter and
+	 * PasswordCellEditor.
+	 */
+	public static final ConfigAttribute<Character> PASSWORD_ECHO_CHAR= new ConfigAttribute<>();
+	
+	/**
+	 * Attribute for configuring the text decoration (underline and/or strikethrough).
+	 * Is used by all specialisations of the AbstractTextPainter
+	 */
+	public static final ConfigAttribute<Set<TextDecorationLine>> TEXT_DECORATION_LINES= new ConfigAttribute<>();
+	
+	public static final ConfigAttribute<Font> CONTROL_FONT= new ConfigAttribute<>();
+	
+	
+	private CellStyling() {
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/GridStyling.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/GridStyling.java
new file mode 100644
index 00000000..df856942
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/GridStyling.java
@@ -0,0 +1,72 @@
+/*=============================================================================#
+ # Copyright (c) 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.style;
+
+import java.util.function.Function;
+
+import org.eclipse.swt.graphics.Color;
+
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.collections.ImIdentityList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
+
+
+@NonNullByDefault
+public class GridStyling {
+	
+	
+	public static final ConfigAttribute<Color> GRID_LINE_COLOR= new ConfigAttribute<>();
+	
+	
+	public static class ConfigGridLineColorSupplier implements Function<ConfigRegistry, Color> {
+		
+		
+		private final ImIdentityList<String> configLabels;
+		
+		
+		public ConfigGridLineColorSupplier(final ImIdentityList<String> configLabels) {
+			this.configLabels= configLabels;
+		}
+		
+		public ConfigGridLineColorSupplier(final String configLabel) {
+			this(ImCollections.newIdentityList(configLabel));
+		}
+		
+		public ConfigGridLineColorSupplier() {
+			this(ImCollections.emptyIdentityList());
+		}
+		
+		
+		@Override
+		public Color apply(final ConfigRegistry configRegistry) {
+			final var value= configRegistry.getAttribute(GridStyling.GRID_LINE_COLOR,
+					DisplayMode.NORMAL, this.configLabels );
+			if (value != null) {
+				return value;
+			}
+			return GUIHelper.COLOR_GRAY;
+		}
+		
+	}
+	
+	private GridStyling() {
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/HorizontalAlignment.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/HorizontalAlignment.java
index 585cab3f..162194fd 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/HorizontalAlignment.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/HorizontalAlignment.java
@@ -11,9 +11,12 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.style;
+package org.eclipse.statet.ecommons.waltable.core.style;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+
+@NonNullByDefault
 public enum HorizontalAlignment {
 	
 	LEFT,
@@ -21,8 +24,4 @@ public enum HorizontalAlignment {
 	RIGHT;
 	
 	
-	private HorizontalAlignment() {
-	}
-	
-	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/RegistryStyle.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/RegistryStyle.java
new file mode 100644
index 00000000..42a7d770
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/RegistryStyle.java
@@ -0,0 +1,85 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.style;
+
+import java.util.List;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+
+
+/**
+ * A style backed by a registry.
+ */
+@NonNullByDefault
+public class RegistryStyle implements Style {
+	
+	
+	private final ConfigRegistry configRegistry;
+	
+	private final ConfigAttribute<Style> styleConfigAttribute;
+	private final DisplayMode targetDisplayMode;
+	private final List<String> configLabels;
+	
+	
+	public RegistryStyle(final ConfigRegistry configRegistry,
+			final ConfigAttribute<Style> styleConfigAttribute,
+			final DisplayMode targetDisplayMode, final List<String> configLabels) {
+		this.configRegistry= configRegistry;
+		this.styleConfigAttribute= styleConfigAttribute;
+		this.targetDisplayMode= targetDisplayMode;
+		this.configLabels= configLabels;
+	}
+	
+	
+	@Override
+	public <T> @Nullable T getAttributeValue(final ConfigAttribute<T> configAttribute) {
+		@Nullable T configAttributeValue= null;
+		for (final DisplayMode displayMode : this.configRegistry.getDisplayModeOrdering()
+				.getDisplayModeOrdering(this.targetDisplayMode) ) {
+			for (final String configLabel : this.configLabels) {
+				final Style style= this.configRegistry
+						.getSpecificAttribute(this.styleConfigAttribute, displayMode, configLabel);
+				if (style != null) {
+					configAttributeValue= style.getAttributeValue(configAttribute);
+					if (configAttributeValue != null) {
+						return configAttributeValue;
+					}
+				}
+			}
+			
+			// default
+			final Style cellStyle= this.configRegistry
+					.getSpecificAttribute(this.styleConfigAttribute, displayMode, null);
+			if (cellStyle != null) {
+				configAttributeValue= cellStyle.getAttributeValue(configAttribute);
+				if (configAttributeValue != null) {
+					return configAttributeValue;
+				}
+			}
+		}
+		
+		return null;
+	}
+	
+	@Override
+	public <T> void setAttributeValue(final ConfigAttribute<T> configAttribute, final @Nullable T value) {
+		throw new UnsupportedOperationException();
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/Style.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/Style.java
new file mode 100644
index 00000000..c2edd6d0
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/Style.java
@@ -0,0 +1,33 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.style;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
+
+
+/**
+ * Used to store attributes reflecting a (usually display) style.
+ */
+@NonNullByDefault
+public interface Style {
+	
+	
+	<T> @Nullable T getAttributeValue(ConfigAttribute<T> configAttribute);
+	
+	<T> void setAttributeValue(ConfigAttribute<T> configAttribute, @Nullable T value);
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/TextDecorationEnum.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/TextDecorationLine.java
index 0f02541e..8519f365 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/TextDecorationEnum.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/TextDecorationLine.java
@@ -11,21 +11,19 @@
  #     Dirk Fauth - initial API and implementation and/or initial documentation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.style;
+package org.eclipse.statet.ecommons.waltable.core.style;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 
 /**
- * Enumeration for text decorations that can be configured for cell styles.
- * <ul>
- * <li>NONE (default) - Render no decoration</li>
- * <li>UNDERLINE - Render the text underlined</li>
- * <li>STRIKETHROUGH - Render the text strike through</li>
- * <li>UNDERLINE_STRIKETHROUGH - Render the text underlined and strike through</li>
- * </ul>
+ * Text decoration line that can be configured for cell styles.
  */
-public enum TextDecorationEnum {
+@NonNullByDefault
+public enum TextDecorationLine {
 	
+	UNDERLINE,
+	STRIKETHROUGH;
 	
-	NONE, UNDERLINE, STRIKETHROUGH, UNDERLINE_STRIKETHROUGH;
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/VerticalAlignment.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/VerticalAlignment.java
index 6c0cf597..1aab0226 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/VerticalAlignment.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/style/VerticalAlignment.java
@@ -11,9 +11,12 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.style;
+package org.eclipse.statet.ecommons.waltable.core.style;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+
+@NonNullByDefault
 public enum VerticalAlignment {
 	
 	TOP,
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/SwtUtils.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/SwtUtils.java
new file mode 100644
index 00000000..6bb05713
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/SwtUtils.java
@@ -0,0 +1,169 @@
+/*=============================================================================#
+ # Copyright (c) 2013, 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.core.swt;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.events.MouseEvent;
+import org.eclipse.swt.graphics.Point;
+import org.eclipse.swt.graphics.Rectangle;
+import org.eclipse.swt.widgets.ScrollBar;
+import org.eclipse.swt.widgets.Scrollable;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle.LineStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+
+
+@NonNullByDefault
+public class SwtUtils {
+	
+	
+	public static final @Nullable ScrollBar getScrollBar(final Scrollable control,
+			final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return control.getHorizontalBar();
+		case VERTICAL:
+			return control.getVerticalBar();
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	
+	public static final int get(final Point point, final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return point.x;
+		case VERTICAL:
+			return point.y;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	public static final int getStart(final Rectangle rect, final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return rect.x;
+		case VERTICAL:
+			return rect.y;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	public static final int getEnd(final Rectangle rect, final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return rect.x + rect.width;
+		case VERTICAL:
+			return rect.y + rect.height;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	public static final int getSize(final Rectangle rect, final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return rect.width;
+		case VERTICAL:
+			return rect.height;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	
+	public static final int toSWT(final long pixel) {
+		if (pixel < Integer.MIN_VALUE || pixel > Integer.MAX_VALUE) {
+			throw new IndexOutOfBoundsException();
+		}
+		return (int)pixel;
+	}
+	
+	public static final Rectangle toSWT(final LRectangle rect) {
+		return new Rectangle(toSWT(rect.x), toSWT(rect.y), toSWT(rect.width), toSWT(rect.height));
+	}
+	
+	public static final LRectangle toNatTable(final Rectangle rect) {
+		return new LRectangle(rect.x, rect.y, rect.width, rect.height);
+	}
+	
+	public static final Point toSWT(final LPoint lPoint) {
+		return new Point(toSWT(lPoint.x), toSWT(lPoint.y));
+	}
+	
+	
+	public static final int toSWT(final HorizontalAlignment alignment) {
+		switch (alignment) {
+		case LEFT:
+			return SWT.LEFT;
+		case CENTER:
+			return SWT.CENTER;
+		case RIGHT:
+			return SWT.RIGHT;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	public static final int toSWT(final LineStyle lineStyle) {
+		switch (lineStyle) {
+		case SOLID:
+			return SWT.LINE_SOLID;
+		case DASHED:
+			return SWT.LINE_DASH;
+		case DOTTED:
+			return SWT.LINE_DOT;
+		case DASHDOT:
+			return SWT.LINE_DASHDOT;
+		case DASHDOTDOT:
+			return SWT.LINE_DASHDOTDOT;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	
+	public static final int getMouseWheelEventType(final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return SWT.MouseHorizontalWheel;
+		case VERTICAL:
+			return SWT.MouseVerticalWheel;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+	public static final int getPixel(final MouseEvent event, final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return event.x;
+		case VERTICAL:
+			return event.y;
+		default:
+			throw new IllegalStateException();
+		}
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/CellLayerPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/painters/CellLayerPainter.java
index de4d0a6b..ca178d69 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/CellLayerPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/painters/CellLayerPainter.java
@@ -11,10 +11,10 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.painter.layer;
+package org.eclipse.statet.ecommons.waltable.core.swt.painters;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
 
 import java.util.Collection;
@@ -25,26 +25,30 @@ import java.util.Map;
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Rectangle;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
 
 
-public class CellLayerPainter implements ILayerPainter {
+@NonNullByDefault
+public class CellLayerPainter implements LayerPainter {
 	
 	
-	protected static final long getEndPosition(final ILayerDim dim, final int pixel) {
-		final long positionByPixel= dim.getPositionByPixel(pixel);
+	public static final long getEndPosition(final LayerDim layerDim, final int pixel) {
+		final long positionByPixel= layerDim.getPositionByPixel(pixel);
 		return ((positionByPixel > 0) ?
-						Math.min(dim.getPositionCount(), positionByPixel) :
-						dim.getPositionCount() );
+						Math.min(layerDim.getPositionCount(), positionByPixel) :
+						layerDim.getPositionCount() );
 	}
 	
-	private static Map<Long, Long> calculateDimensionInfo(final ILayerDim dim,
+	private static Map<Long, Long> calculateDimensionInfo(final LayerDim dim,
 			final long startPosition, final long endPosition) {
 		final Map<Long, Long> positionToPixelMap= new HashMap<>();
 		long start2= (startPosition > 0) ?
@@ -63,7 +67,7 @@ public class CellLayerPainter implements ILayerPainter {
 		return positionToPixelMap;
 	}
 	
-	private static long getPositionStart(final ILayerDim dim, final long position,
+	private static long getPositionStart(final LayerDim dim, final long position,
 			final Map<Long, Long> positionToPixelMap) {
 		if (position < dim.getPositionCount()) {
 			Long start= positionToPixelMap.get(position);
@@ -86,15 +90,26 @@ public class CellLayerPainter implements ILayerPainter {
 	}
 	
 	
-	private ILayer natLayer;
+	private Layer natLayer;
 	
 	private Map<Long, Long> horizontalPositionToPixelMap;
 	private Map<Long, Long> verticalPositionToPixelMap;
 	
 	
+	@SuppressWarnings("null")
+	public CellLayerPainter() {
+	}
+	
+	
+	@Override
+	public LRectangle adjustCellBounds(final long columnPosition, final long rowPosition,
+			final LRectangle cellBounds) {
+		return cellBounds;
+	}
+	
 	@Override
-	public void paintLayer(final ILayer natLayer, final GC gc, final int xOffset, final int yOffset,
-			final Rectangle pixelRectangle, final IConfigRegistry configRegistry) {
+	public void paintLayer(final Layer natLayer, final GC gc, final int xOffset, final int yOffset,
+			final Rectangle pixelRectangle, final ConfigRegistry configRegistry) {
 		if (pixelRectangle.isEmpty()) {
 			return;
 		}
@@ -104,11 +119,11 @@ public class CellLayerPainter implements ILayerPainter {
 		
 		calculateDimensionInfo(positionRectangle);
 		
-		final Collection<ILayerCell> spannedCells= new HashSet<>();
+		final Collection<LayerCell> spannedCells= new HashSet<>();
 		
 		for (long columnPosition= positionRectangle.x; columnPosition < positionRectangle.x + positionRectangle.width; columnPosition++) {
 			for (long rowPosition= positionRectangle.y; rowPosition < positionRectangle.y + positionRectangle.height; rowPosition++) {
-				final ILayerCell cell= natLayer.getCellByPosition(columnPosition, rowPosition);
+				final LayerCell cell= natLayer.getCellByPosition(columnPosition, rowPosition);
 				if (cell != null) {
 					if (cell.isSpannedCell()) {
 						spannedCells.add(cell);
@@ -120,7 +135,7 @@ public class CellLayerPainter implements ILayerPainter {
 			}
 		}
 		
-		for (final ILayerCell cell : spannedCells) {
+		for (final LayerCell cell : spannedCells) {
 			paintCell(cell, gc, configRegistry);
 		}
 	}
@@ -134,12 +149,7 @@ public class CellLayerPainter implements ILayerPainter {
 				positionRectangle.y, positionRectangle.y + positionRectangle.height);
 	}
 	
-	@Override
-	public LRectangle adjustCellBounds(final long columnPosition, final long rowPosition, final LRectangle cellBounds) {
-		return cellBounds;
-	}
-	
-	protected LRectangle getPositionRectangleFromPixelRectangle(final ILayer natLayer, final Rectangle pixelRectangle) {
+	protected LRectangle getPositionRectangleFromPixelRectangle(final Layer natLayer, final Rectangle pixelRectangle) {
 		final long columnPositionOffset= natLayer.getColumnPositionByX(pixelRectangle.x);
 		final long rowPositionOffset= natLayer.getRowPositionByY(pixelRectangle.y);
 		final long numColumns= natLayer.getColumnPositionByX(Math.min(natLayer.getWidth(), pixelRectangle.x + pixelRectangle.width) - 1) - columnPositionOffset + 1;
@@ -153,15 +163,15 @@ public class CellLayerPainter implements ILayerPainter {
 		return new LRectangle(columnPositionOffset, rowPositionOffset, numColumns, numRows);
 	}
 	
-	protected void paintCell(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
-		final ILayer layer= cell.getLayer();
+	protected void paintCell(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
+		final Layer layer= cell.getLayer();
 		final long columnPosition= cell.getColumnPosition();
 		final long rowPosition= cell.getRowPosition();
 		
-		final ICellPainter cellPainter= configRegistry.getConfigAttribute(CellConfigAttributes.CELL_PAINTER,
-				cell.getDisplayMode(), cell.getConfigLabels().getLabels() );
+		final LayerCellPainter layerCellPainter= configRegistry.getAttribute(CellConfigAttributes.CELL_PAINTER,
+				cell.getDisplayMode(), cell.getLabels().getLabels() );
 		final LRectangle adjustedCellBounds= layer.getLayerPainter().adjustCellBounds(columnPosition, rowPosition, cell.getBounds());
-		if (cellPainter != null) {
+		if (layerCellPainter != null) {
 			final Rectangle originalClipping= gc.getClipping();
 			
 			final long startX= getColumnPositionStart(columnPosition);
@@ -175,7 +185,7 @@ public class CellLayerPainter implements ILayerPainter {
 //			LRectangle adjustedClipBounds= layer.getLayerPainter().adjustCellBounds(columnPosition, rowPosition, clipBounds);
 			gc.setClipping(safe(adjustedClipBounds));
 			
-			cellPainter.paintCell(cell, gc, adjustedCellBounds, configRegistry);
+			layerCellPainter.paintCell(cell, gc, adjustedCellBounds, configRegistry);
 			
 			gc.setClipping(originalClipping);
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/GridLineCellLayerPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/painters/GridLineCellLayerPainter.java
index d37c61a6..f5d21fdb 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/GridLineCellLayerPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/painters/GridLineCellLayerPainter.java
@@ -11,70 +11,65 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.painter.layer;
+package org.eclipse.statet.ecommons.waltable.core.swt.painters;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
 
+import java.util.function.Function;
+
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Rectangle;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.style.GridStyling.ConfigGridLineColorSupplier;
 
 
+@NonNullByDefault
 public class GridLineCellLayerPainter extends CellLayerPainter {
 	
 	
-	private final Color gridColor;
+	private final Function<ConfigRegistry, Color> gridLineColorSupplier;
 	
 	
-	public GridLineCellLayerPainter(final Color gridColor) {
-		this.gridColor= gridColor;
+	public GridLineCellLayerPainter(final Function<ConfigRegistry, Color> gridLineColorSupplier) {
+		this.gridLineColorSupplier= gridLineColorSupplier;
 	}
 	
 	public GridLineCellLayerPainter() {
-		this.gridColor= GUIHelper.COLOR_GRAY;
+		this(new ConfigGridLineColorSupplier());
 	}
 	
 	
-	public Color getGridColor() {
-		return this.gridColor;
+	@Override
+	public LRectangle adjustCellBounds(final long columnPosition, final long rowPosition,
+			final LRectangle bounds) {
+		return new LRectangle(bounds.x, bounds.y, Math.max(bounds.width - 1, 0), Math.max(bounds.height - 1, 0));
 	}
 	
-	
 	@Override
-	public void paintLayer(final ILayer natLayer, final GC gc,
+	public void paintLayer(final Layer natLayer, final GC gc,
 			final int xOffset, final int yOffset, final Rectangle pixelRectangle,
-			final IConfigRegistry configRegistry) {
-		//Draw GridLines
-		drawGridLines(natLayer, gc, pixelRectangle);
+			final ConfigRegistry configRegistry) {
+		gc.setForeground(this.gridLineColorSupplier.apply(configRegistry));
+		drawHorizontalLines(natLayer, gc, pixelRectangle);
+		drawVerticalLines(natLayer, gc, pixelRectangle);
 		
 		super.paintLayer(natLayer, gc, xOffset, yOffset, pixelRectangle, configRegistry);
 	}
 	
-	@Override
-	public LRectangle adjustCellBounds(final long columnPosition, final long rowPosition, final LRectangle bounds) {
-		return new LRectangle(bounds.x, bounds.y, Math.max(bounds.width - 1, 0), Math.max(bounds.height - 1, 0));
-	}
-	
-	protected void drawGridLines(final ILayer natLayer, final GC gc, final Rectangle rectangle) {
-		gc.setForeground(this.gridColor);
-		
-		drawHorizontalLines(natLayer, gc, rectangle);
-		drawVerticalLines(natLayer, gc, rectangle);
-	}
-	
-	private void drawHorizontalLines(final ILayer natLayer, final GC gc, final Rectangle rectangle) {
+	protected void drawHorizontalLines(final Layer natLayer, final GC gc, final Rectangle rectangle) {
 		final int startX= safe(rectangle.x);
 		final int endX= safe(rectangle.x + Math.min(natLayer.getWidth() - 1, rectangle.width));
 		
-		final ILayerDim dim= natLayer.getDim(VERTICAL);
+		final LayerDim dim= natLayer.getDim(VERTICAL);
 		final long endPosition= Math.min(dim.getPositionCount(), dim.getPositionByPixel(rectangle.y + rectangle.height - 1) + 1);
 		for (long position= dim.getPositionByPixel(rectangle.y); position < endPosition; position++) {
 			final int size= dim.getPositionSize(position);
@@ -85,11 +80,11 @@ public class GridLineCellLayerPainter extends CellLayerPainter {
 		}
 	}
 	
-	private void drawVerticalLines(final ILayer natLayer, final GC gc, final Rectangle rectangle) {
+	protected void drawVerticalLines(final Layer natLayer, final GC gc, final Rectangle rectangle) {
 		final int startY= safe(rectangle.y);
 		final int endY= safe(rectangle.y + Math.min(natLayer.getHeight() - 1, rectangle.height));
 		
-		final ILayerDim dim= natLayer.getDim(HORIZONTAL);
+		final LayerDim dim= natLayer.getDim(HORIZONTAL);
 		final long endPosition= Math.min(dim.getPositionCount(), dim.getPositionByPixel(rectangle.x + rectangle.width - 1) + 1);
 		for (long position= dim.getPositionByPixel(rectangle.x); position < endPosition; position++) {
 			final long size= dim.getPositionSize(position);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/NatGridLayerPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/painters/TableGridLayerPainter.java
index 3a07c849..ef270ae8 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/NatGridLayerPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/painters/TableGridLayerPainter.java
@@ -11,40 +11,40 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.painter.layer;
+package org.eclipse.statet.ecommons.waltable.core.swt.painters;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
 
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
+import org.eclipse.swt.graphics.Rectangle;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
 
 
-public class NatGridLayerPainter extends NatLayerPainter {
+@NonNullByDefault
+public class TableGridLayerPainter extends TableLayerPainter {
 	
 	
 	private final Color gridColor;
 	
 	
-	public NatGridLayerPainter(final NatTable natTable) {
-		this(natTable, GUIHelper.COLOR_GRAY);
-	}
-	
-	public NatGridLayerPainter(final NatTable natTable, final Color gridColor) {
+	public TableGridLayerPainter(final NatTable natTable, final Color gridColor) {
 		super(natTable);
 		this.gridColor= gridColor;
 	}
 	
 	
 	@Override
-	protected void paintBackground(final ILayer natLayer, final GC gc, final long xOffset, final long yOffset, final org.eclipse.swt.graphics.Rectangle rectangle, final IConfigRegistry configRegistry) {
+	protected void paintBackground(final Layer natLayer, final GC gc, final long xOffset, final long yOffset,
+			final Rectangle rectangle, final ConfigRegistry configRegistry) {
 		super.paintBackground(natLayer, gc, xOffset, yOffset, rectangle, configRegistry);
 		
 		gc.setForeground(this.gridColor);
@@ -52,11 +52,12 @@ public class NatGridLayerPainter extends NatLayerPainter {
 		drawVerticalLines(natLayer, gc, rectangle);
 	}
 	
-	private void drawHorizontalLines(final ILayer natLayer, final GC gc, final org.eclipse.swt.graphics.Rectangle rectangle) {
+	private void drawHorizontalLines(final Layer natLayer, final GC gc,
+			final Rectangle rectangle) {
 		final int startX= rectangle.x;
 		final int endX= rectangle.x + rectangle.width;
 		
-		final ILayerDim dim= natLayer.getDim(VERTICAL);
+		final LayerDim dim= natLayer.getDim(VERTICAL);
 		final long endPosition= CellLayerPainter.getEndPosition(dim, rectangle.y + rectangle.height);
 		for (long position= dim.getPositionByPixel(rectangle.y); position < endPosition; position++) {
 			final int size= dim.getPositionSize(position);
@@ -67,11 +68,12 @@ public class NatGridLayerPainter extends NatLayerPainter {
 		}
 	}
 	
-	private void drawVerticalLines(final ILayer natLayer, final GC gc, final org.eclipse.swt.graphics.Rectangle rectangle) {
+	private void drawVerticalLines(final Layer natLayer, final GC gc,
+			final Rectangle rectangle) {
 		final int startY= rectangle.y;
 		final int endY= rectangle.y + rectangle.height;
 		
-		final ILayerDim dim= natLayer.getDim(HORIZONTAL);
+		final LayerDim dim= natLayer.getDim(HORIZONTAL);
 		final long endPosition= CellLayerPainter.getEndPosition(dim, rectangle.x + rectangle.width);
 		for (long position= dim.getPositionByPixel(rectangle.x); position < endPosition; position++) {
 			final int size= dim.getPositionSize(position);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/NatLayerPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/painters/TableLayerPainter.java
index 64b292e7..0fde1d7e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/layer/NatLayerPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/core/swt/painters/TableLayerPainter.java
@@ -11,74 +11,83 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.painter.layer;
+package org.eclipse.statet.ecommons.waltable.core.swt.painters;
 
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Rectangle;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.painter.IOverlayPainter;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.top.OverlayPainter;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
-public class NatLayerPainter implements ILayerPainter {
+@NonNullByDefault
+public class TableLayerPainter implements LayerPainter {
 	
 	
 	private final NatTable natTable;
 	
 	
-	public NatLayerPainter(final NatTable natTable) {
+	public TableLayerPainter(final NatTable natTable) {
 		this.natTable= natTable;
 	}
 	
 	
 	@Override
-	public void paintLayer(final ILayer natLayer, final GC gc,
+	public LRectangle adjustCellBounds(final long columnPosition, final long rowPosition,
+			final LRectangle cellBounds) {
+		final var layerPainter= this.natTable.getUnderlyingLayer().getLayerPainter();
+		return layerPainter.adjustCellBounds(columnPosition, rowPosition, cellBounds);
+	}
+	
+	@Override
+	public void paintLayer(final Layer natLayer, final GC gc,
 			final int xOffset, final int yOffset, final Rectangle pixelRectangle,
-			final IConfigRegistry configRegistry) {
+			final ConfigRegistry configRegistry) {
 		try {
 			paintBackground(natLayer, gc, xOffset, yOffset, pixelRectangle, configRegistry);
 			
 			gc.setForeground(this.natTable.getForeground());
 			
-			final Rectangle paintRectangle= pixelRectangle.intersection(SWTUtil.toSWT(
+			final Rectangle paintRectangle= pixelRectangle.intersection(SwtUtils.toSWT(
 					new LRectangle(xOffset, yOffset, natLayer.getWidth(), natLayer.getHeight()) ));
 			
 			if (!paintRectangle.isEmpty()) {
-				this.natTable.getLayer().getLayerPainter().paintLayer(natLayer, gc,
-						xOffset, yOffset, paintRectangle, configRegistry );
+				final var layerPainter= this.natTable.getUnderlyingLayer().getLayerPainter();
+				layerPainter.paintLayer(natLayer, gc, xOffset, yOffset,
+						paintRectangle, configRegistry );
 			}
 			
 			paintOverlays(natLayer, gc, xOffset, yOffset, pixelRectangle, configRegistry);
-		} catch (final Exception e) {
+		}
+		catch (final Exception e) {
 			WaLTablePlugin.log(new Status(IStatus.ERROR, WaLTablePlugin.BUNDLE_ID,
 					"An error occurred while painting the table.", e ));
 		}
 	}
 	
-	protected void paintBackground(final ILayer natLayer, final GC gc, final long xOffset, final long yOffset, final org.eclipse.swt.graphics.Rectangle rectangle, final IConfigRegistry configRegistry) {
+	protected void paintBackground(final Layer natLayer, final GC gc, final long xOffset, final long yOffset,
+			final Rectangle rectangle, final ConfigRegistry configRegistry) {
 		gc.setBackground(this.natTable.getBackground());
 		
 		// Clean Background
 		gc.fillRectangle(rectangle);
 	}
 	
-	protected void paintOverlays(final ILayer natLayer, final GC gc, final long xOffset, final long yOffset, final org.eclipse.swt.graphics.Rectangle rectangle, final IConfigRegistry configRegistry) {
-		for (final IOverlayPainter overlayPainter : this.natTable.getOverlayPainters()) {
+	protected void paintOverlays(final Layer natLayer, final GC gc, final long xOffset, final long yOffset,
+			final Rectangle rectangle, final ConfigRegistry configRegistry) {
+		for (final OverlayPainter overlayPainter : this.natTable.getOverlayPainters()) {
 			overlayPainter.paintOverlay(gc, this.natTable);
 		}
 	}
 	
-	@Override
-	public LRectangle adjustCellBounds(final long columnPosition, final long rowPosition, final LRectangle cellBounds) {
-		final ILayerPainter layerPainter= this.natTable.getLayer().getLayerPainter();
-		return layerPainter.adjustCellBounds(columnPosition, rowPosition, cellBounds);
-	}
-	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/AbstractFilterListDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/AbstractFilterListDataProvider.java
deleted file mode 100644
index 04910351..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/AbstractFilterListDataProvider.java
+++ /dev/null
@@ -1,137 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.data;
-
-import java.util.List;
-
-import org.eclipse.core.runtime.IProgressMonitor;
-
-
-/**
- * Enables the use of a {@link List} containing POJO(s) as a backing data source.
- * 
- * By default a bean at position 'X' in the list is displayed in 
- * row 'X' in the table. The properties of the bean are used to 
- * populate the columns. A {@link IColumnPropertyResolver} is used to
- * retrieve column data from the bean properties. 
- * 
- * By implementing filter logic within {@link AbstractFilterListDataProvider#show(Object)}
- * it is possible to create a static filter. All data access methods will skip invisible
- * items within the wrapped list and delegate access to the visible items.
- * 
- * NOTE: This way of static filtering can cause performance issues for huge data sets
- * where a lot of items are filtered, because data access will always calculate the visible row
- * position. Trying to use a caching mechanism would create some issues for deleting or inserting
- * new data to the wrapped list.
- * 
- * TODO add caching that reacts on insert/delete actions on the wrapped list
- * 
- * @param <T> type of the Objects in the backing list.
- * @see IColumnPropertyResolver
- */
-public abstract class AbstractFilterListDataProvider<T> extends ListDataProvider<T> {
-	
-	public AbstractFilterListDataProvider(final List<T> list, final IColumnAccessor<T> columnAccessor) {
-		super(list, columnAccessor);
-	}
-
-	/**
-	 * Iterates over the whole list of data objects and checks the visibility for
-	 * every object. The number of non visible items will be subtracted from the
-	 * size of the wrapped list to return the number of visible items.
-	 */
-	@Override
-	public long getRowCount() {
-		long numberOfInvisible= 0;
-		for (final T object : this.list) {
-			if (!show(object)) {
-				numberOfInvisible++;
-			}
-		}
-		return this.list.size() - numberOfInvisible;
-	}
-
-	/**
-	 * Get the data value for the columnIndex and the visible rowIndex.
-	 */
-	@Override
-	public Object getDataValue(final long columnIndex, final long rowIndex, final int flags, final IProgressMonitor monitor) {
-		final T rowObj= getRowObject(rowIndex);
-		return this.columnAccessor.getDataValue(rowObj, columnIndex);
-	}
-	
-	/**
-	 * Set the data value for the columnIndex and the visible rowIndex.
-	 */
-	@Override
-	public void setDataValue(final long columnIndex, final long rowIndex, final Object newValue) {
-		final T rowObj= getRowObject(rowIndex);
-		this.columnAccessor.setDataValue(rowObj, columnIndex, newValue);
-	}
-
-	/**
-	 * Returns the object for the visible rowIndex.
-	 * To do this it is iterated over the wrapped list, taking the invisible
-	 * items into account, so the real row index for the given visible row index
-	 * is calculated.
-	 */
-	@Override
-	public T getRowObject(final long rowIndex) {
-		if (rowIndex >= Integer.MAX_VALUE) {
-			return null;
-		}
-		T object= null;
-		long count= 0;
-		int realRowIndex= 0;
-		while (count <= rowIndex) {
-			object= this.list.get(realRowIndex);
-			if (show(object)) {
-				count++;
-			}
-			realRowIndex++;
-		}
-		
-		return object;
-	}
-	
-	/**
-	 * Returns the visible rowIndex for the given object.
-	 * To do this the real row index for the object within the wrapped list
-	 * is searched and then all invisible items are subtracted from the
-	 * real row index to calculate the visible row index.
-	 */
-	@Override
-	public long indexOfRowObject(final T rowObject) {
-		final int realRowIndex= this.list.indexOf(rowObject);
-		int filteredIndex= realRowIndex;
-		//now find number of not visible items
-		T vf= null;
-		for (int i= 0; i <= realRowIndex; i++) {
-			vf= this.list.get(i);
-			if (!show(vf)) {
-				filteredIndex--;
-			}
-		}
-		return filteredIndex;
-	}
-	
-	/**
-	 * Within this method the filter logic should be applied.
-	 * Return false if the object should not be visible within the grid.
-	 * Return true if it should be visible.
-	 * @param object The object that should be checked.
-	 * @return true if the object should be visible, false if not
-	 */
-	protected abstract boolean show(T object);
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ExtendedReflectiveColumnPropertyAccessor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ExtendedReflectiveColumnPropertyAccessor.java
deleted file mode 100644
index 1ae870cd..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ExtendedReflectiveColumnPropertyAccessor.java
+++ /dev/null
@@ -1,157 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.data;
-
-import java.lang.reflect.Method;
-import java.util.Locale;
-
-
-public class ExtendedReflectiveColumnPropertyAccessor<R> extends ReflectiveColumnPropertyAccessor<R> {
-
-	/**
-	 * @param propertyNames of the members of the row bean
-	 */
-	public ExtendedReflectiveColumnPropertyAccessor(final String[] propertyNames) {
-		super(propertyNames);
-	}
-
-	@Override
-	public Object getDataValue(final R rowObj, final long columnIndex) {
-		final String propertyName= getColumnProperty(columnIndex);
-		if (propertyName.contains(".")) { //$NON-NLS-1$
-			return getPropertyValue(rowObj, propertyName);
-		}
-		else {
-			return super.getDataValue(rowObj, columnIndex);
-		}
-	}
-
-	@Override
-	public void setDataValue(final R rowObj, final long columnIndex, final Object newValue) {
-		final String propertyName= getColumnProperty(columnIndex);
-		if (propertyName.contains(".")) { //$NON-NLS-1$
-			setPropertyValue(rowObj, propertyName, newValue);
-		}
-		else {
-			super.setDataValue(rowObj, columnIndex, newValue);
-		}
-	}
-
-	
-	/**
-	 * Reads the value of a property out of a given bean via reflection.
-	 * @param object the bean out of which the property value should be read
-	 * @param propertyName the name of the property which value should be read
-	 * @return the property value of the bean
-	 */
-	private Object getPropertyValue(final Object object, final String propertyName) {
-		assert object != null : "object can not be null!"; //$NON-NLS-1$
-
-		String[] propertyChain= null;
-		if (propertyName.contains(".")) { //$NON-NLS-1$
-			propertyChain= propertyName.split("\\."); //$NON-NLS-1$
-		}
-		else {
-			propertyChain= new String[] {propertyName};
-		}
-
-		Object child= object;
-		Class<?> objectClass= object.getClass();
-		String getterName= null;
-		Method getterMethod= null;
-		for (final String pc : propertyChain) {
-			getterName= "get" + pc.substring(0, 1).toUpperCase(Locale.ROOT) + pc.substring(1); //$NON-NLS-1$
-			try {
-				getterMethod= objectClass.getMethod(getterName);
-				child= getterMethod.invoke(child);
-			}
-			catch (final NoSuchMethodException e) {
-				try {
-					getterName= "is" + pc.substring(0, 1).toUpperCase(Locale.ROOT) + pc.substring(1); //$NON-NLS-1$
-					getterMethod= objectClass.getMethod(getterName);
-					child= getterMethod.invoke(child);
-				}
-				catch (final Exception e1) {
-					e.printStackTrace();
-					throw new RuntimeException(e);
-				}
-			}
-			catch (final Exception e) {
-				e.printStackTrace();
-				throw new RuntimeException(e);
-			}
-			
-			if (child != null) {
-				objectClass= child.getClass();
-			}
-			else {
-				//null is returned by reflection, therefore we can not go further
-				//and null is the correct return value
-				break;
-			}
-		}
-		
-		return child;
-	}
-
-	/**
-	 * Sets a value to the property of a bean via reflection.
-	 * Also supports dot separated property names to access properties anywhere within the
-	 * object graph.
-	 * @param object the bean where the property value should be set
-	 * @param propertyName the name of the property which should be set
-	 * @param value the value to set
-	 */
-	private void setPropertyValue(final Object object, final String propertyName, final Object value) {
-		assert object != null : "object can not be null!"; //$NON-NLS-1$
-		
-		try {
-			Object singlePropertyObject= null;
-			String singlePropertyName= null;
-			if (propertyName.contains(".")) { //$NON-NLS-1$
-				singlePropertyObject= 
-					getPropertyValue(object, propertyName.substring(0, propertyName.lastIndexOf("."))); //$NON-NLS-1$
-				singlePropertyName= propertyName.substring(propertyName.lastIndexOf(".") + 1); //$NON-NLS-1$
-			}
-			else {
-				singlePropertyObject= object;
-				singlePropertyName= propertyName;
-			}
-			
-			
-			final String setterName= "set"  //$NON-NLS-1$
-				+ singlePropertyName.substring(0, 1).toUpperCase() 
-				+ singlePropertyName.substring(1);
-			Method setterMethod= null;
-			if (value != null) {
-				setterMethod= singlePropertyObject.getClass().getMethod(setterName, new Class<?>[] {value.getClass()});
-			}
-			else {
-				//as the value is null we can not access the setter method directly
-				//and have to search for the method
-				final Method[] methods= singlePropertyObject.getClass().getMethods();
-				for (final Method m : methods) {
-					if (m.getName().equals(setterName)) {
-						setterMethod= m;
-					}
-				}
-			}
-			setterMethod.invoke(singlePropertyObject, value);
-		} catch (final Exception e) {
-			e.printStackTrace();
-			throw new RuntimeException(e);
-		}
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IRowDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IRowDataProvider.java
deleted file mode 100644
index 41f783af..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IRowDataProvider.java
+++ /dev/null
@@ -1,24 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.data;
-
-
-public interface IRowDataProvider<T> extends IDataProvider {
-	
-	
-	T getRowObject(long rowIndex);
-	
-	long indexOfRowObject(T rowObject);
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/DisplayConverter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/DisplayConverter.java
index 76e1b386..3e3dcbf9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/DisplayConverter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/DisplayConverter.java
@@ -13,8 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.data.convert;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 public abstract class DisplayConverter implements IDisplayConverter {
@@ -24,12 +24,12 @@ public abstract class DisplayConverter implements IDisplayConverter {
 	public abstract Object displayToCanonicalValue(Object displayValue);
 	
 	@Override
-	public Object canonicalToDisplayValue(final ILayerCell cell, final IConfigRegistry configRegistry, final Object canonicalValue) {
+	public Object canonicalToDisplayValue(final LayerCell cell, final ConfigRegistry configRegistry, final Object canonicalValue) {
 		return canonicalToDisplayValue(canonicalValue);
 	}
 
 	@Override
-	public Object displayToCanonicalValue(final ILayerCell cell, final IConfigRegistry configRegistry, final Object displayValue) {
+	public Object displayToCanonicalValue(final LayerCell cell, final ConfigRegistry configRegistry, final Object displayValue) {
 		return displayToCanonicalValue(displayValue);
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/IDisplayConverter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/IDisplayConverter.java
index ffa51ea4..f247c04f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/IDisplayConverter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/IDisplayConverter.java
@@ -13,8 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.data.convert;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 /**
@@ -35,7 +35,7 @@ public interface IDisplayConverter {
 	 * Typically converted to a String for display.
 	 * Use this method for contextual conversion.
 	 */
-	public Object canonicalToDisplayValue(ILayerCell cell, IConfigRegistry configRegistry, Object canonicalValue);
+	public Object canonicalToDisplayValue(LayerCell cell, ConfigRegistry configRegistry, Object canonicalValue);
 	
 	/**
 	 * Convert from display value to value in the backing data structure.
@@ -44,6 +44,6 @@ public interface IDisplayConverter {
 	 * in the setter of the backing bean/row object
 	 * Use this method for contextual conversion.
 	 */
-	public Object displayToCanonicalValue(ILayerCell cell, IConfigRegistry configRegistry, Object displayValue);
+	public Object displayToCanonicalValue(LayerCell cell, ConfigRegistry configRegistry, Object displayValue);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/PercentageDisplayConverter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/PercentageDisplayConverter.java
index b962e1a1..5df96a11 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/PercentageDisplayConverter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/convert/PercentageDisplayConverter.java
@@ -34,7 +34,7 @@ public class PercentageDisplayConverter extends DisplayConverter {
 			displayString= displayString.substring(0, displayString.length() - 1);
 		}
 		displayString= displayString.trim();
-		final int displayInt= Integer.valueOf(displayString).intValue();
+		final int displayInt= Integer.parseInt(displayString);
 		final double percentageValue= (double) displayInt / 100;
 		return Double.valueOf(percentageValue);
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/ContextualDataValidator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/ContextualDataValidator.java
index 6df5002b..07d1433f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/ContextualDataValidator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/ContextualDataValidator.java
@@ -13,8 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.data.validate;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 public abstract class ContextualDataValidator implements IDataValidator {
@@ -27,6 +27,6 @@ public abstract class ContextualDataValidator implements IDataValidator {
 	}
 	
 	@Override
-	public abstract boolean validate(ILayerCell cell, IConfigRegistry configRegistry, Object newValue);
+	public abstract boolean validate(LayerCell cell, ConfigRegistry configRegistry, Object newValue);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/DataValidator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/DataValidator.java
index 6427cdd3..cee4dca5 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/DataValidator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/DataValidator.java
@@ -13,18 +13,18 @@
 
 package org.eclipse.statet.ecommons.waltable.data.validate;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 public abstract class DataValidator implements IDataValidator {
 	
 	
 	@Override
-	public boolean validate(final ILayerCell cell, final IConfigRegistry configRegistry, final Object newValue) {
+	public boolean validate(final LayerCell cell, final ConfigRegistry configRegistry, final Object newValue) {
 		return validate(cell.getDim(HORIZONTAL).getId(), cell.getDim(VERTICAL).getId(),
 				newValue );
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/IDataValidator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/IDataValidator.java
index 9c859df6..e4e9b7b3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/IDataValidator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/validate/IDataValidator.java
@@ -13,11 +13,11 @@
 
 package org.eclipse.statet.ecommons.waltable.data.validate;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
 import org.eclipse.statet.ecommons.waltable.edit.editor.TextCellEditor;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 
 
 public interface IDataValidator {
@@ -31,7 +31,7 @@ public interface IDataValidator {
 	 * 	will be converted to the canonical value using the {@link IDisplayConverter}
 	 * 	before it hits this method
 	 *
-	 * @see IDataProvider#getDataValue(int, int)
+	 * @see DataProvider#getDataValue(int, int)
 	 *
 	 * @return true is newValue is valid. False otherwise.
 	 */
@@ -46,16 +46,16 @@ public interface IDataValidator {
 	 * 	will be converted to the canonical value using the {@link IDisplayConverter}
 	 * 	before it hits this method
 	 *
-	 * @see IDataProvider#getDataValue(int, int)
+	 * @see DataProvider#getDataValue(int, int)
 	 *
 	 * @return true is newValue is valid. False otherwise.
 	 */
-	public boolean validate(ILayerCell cell, IConfigRegistry configRegistry, Object newValue);
+	public boolean validate(LayerCell cell, ConfigRegistry configRegistry, Object newValue);
 
 	public static final IDataValidator ALWAYS_VALID= new IDataValidator() {
 
 		@Override
-		public boolean validate(final ILayerCell cell, final IConfigRegistry configRegistry, final Object newValue) {
+		public boolean validate(final LayerCell cell, final ConfigRegistry configRegistry, final Object newValue) {
 			return true;
 		}
 
@@ -69,7 +69,7 @@ public interface IDataValidator {
 	public static final IDataValidator NEVER_VALID= new IDataValidator() {
 
 		@Override
-		public boolean validate(final ILayerCell cell, final IConfigRegistry configRegistry, final Object newValue) {
+		public boolean validate(final LayerCell cell, final ConfigRegistry configRegistry, final Object newValue) {
 			return false;
 		}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/DialogEditHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/DialogEditHandler.java
index 24b65a49..872b716a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/DialogEditHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/DialogEditHandler.java
@@ -13,7 +13,7 @@
 
 package org.eclipse.statet.ecommons.waltable.edit;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditCellCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditCellCommand.java
index e40abe68..f2f7accb 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditCellCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditCellCommand.java
@@ -15,9 +15,9 @@ package org.eclipse.statet.ecommons.waltable.edit;
 
 import org.eclipse.swt.widgets.Composite;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 /**
@@ -29,13 +29,13 @@ import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 public class EditCellCommand extends AbstractContextFreeCommand {
 	
 	/**
-	 * The {@link IConfigRegistry} containing the configuration of the current NatTable 
+	 * The {@link ConfigRegistry} containing the configuration of the current NatTable 
 	 * instance the command should be executed for.
 	 * <p>
 	 * This is necessary because the edit controllers in the current architecture
 	 * are not aware of the instance they are running in.
 	 */
-	private final IConfigRegistry configRegistry;
+	private final ConfigRegistry configRegistry;
 	/**
 	 * The parent Composite, needed for the creation of the editor control.
 	 */
@@ -43,28 +43,28 @@ public class EditCellCommand extends AbstractContextFreeCommand {
 	/**
 	 * The cell that should be put in edit mode.
 	 */
-	private final ILayerCell cell;
+	private final LayerCell cell;
 
 	/**
 	 * 
 	 * @param parent The parent Composite, needed for the creation of the editor control.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of the
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of the
 	 * 			current NatTable instance the command should be executed for.
 	 * 			This is necessary because the edit controllers in the current architecture
 	 * 			are not aware of the instance they are running in.
 	 * @param cell The cell that should be put into the edit mode.
 	 */
-	public EditCellCommand(final Composite parent, final IConfigRegistry configRegistry, final ILayerCell cell) {
+	public EditCellCommand(final Composite parent, final ConfigRegistry configRegistry, final LayerCell cell) {
 		this.configRegistry= configRegistry;
 		this.parent= parent;
 		this.cell= cell;
 	}
 
 	/**
-	 * @return The {@link IConfigRegistry} containing the configuration of the current NatTable 
+	 * @return The {@link ConfigRegistry} containing the configuration of the current NatTable 
 	 * 			instance the command should be executed for.
 	 */
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getConfigRegistry() {
 		return this.configRegistry;
 	}
 	
@@ -78,7 +78,7 @@ public class EditCellCommand extends AbstractContextFreeCommand {
 	/**
 	 * @return The cell that should be put in edit mode.
 	 */
-	public ILayerCell getCell() {
+	public LayerCell getCell() {
 		return this.cell;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditCellCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditCellCommandHandler.java
index 355f19ee..a9d21ea4 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditCellCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditCellCommandHandler.java
@@ -15,11 +15,11 @@ package org.eclipse.statet.ecommons.waltable.edit;
 
 import org.eclipse.swt.widgets.Composite;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.config.IEditableRule;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 /**
@@ -37,14 +37,14 @@ public class EditCellCommandHandler extends AbstractLayerCommandHandler<EditCell
 	
 	@Override
 	public boolean doCommand(final EditCellCommand command) {
-		final ILayerCell cell= command.getCell();
+		final LayerCell cell= command.getCell();
 		final Composite parent= command.getParent();
-		final IConfigRegistry configRegistry= command.getConfigRegistry();
+		final ConfigRegistry configRegistry= command.getConfigRegistry();
 		
 		//check if the cell is editable
-		final IEditableRule rule= configRegistry.getConfigAttribute(
+		final IEditableRule rule= configRegistry.getAttribute(
 				EditConfigAttributes.CELL_EDITABLE_RULE, 
-				DisplayMode.EDIT, cell.getConfigLabels().getLabels());
+				DisplayMode.EDIT, cell.getLabels().getLabels());
 		
 		if (rule.isEditable(cell, configRegistry)) {
 			EditController.editCell(cell, parent, cell.getDataValue(0, null), configRegistry);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditConfigAttributes.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditConfigAttributes.java
index fd7b8b1f..85b4c54a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditConfigAttributes.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditConfigAttributes.java
@@ -16,14 +16,14 @@ package org.eclipse.statet.ecommons.waltable.edit;
 import java.util.List;
 import java.util.Map;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.config.IEditableRule;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.data.validate.IDataValidator;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
 import org.eclipse.statet.ecommons.waltable.edit.editor.IEditErrorHandler;
 import org.eclipse.statet.ecommons.waltable.edit.gui.ICellEditDialog;
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
 
 
 /**
@@ -70,7 +70,7 @@ public interface EditConfigAttributes {
 	 * Note: Currently this configuration attribute is only evaluated by the TextCellEditor in combination
 	 * 		 with the RenderErrorHandling for just in time conversion error rendering. 
 	 */
-	public static final ConfigAttribute<IStyle> CONVERSION_ERROR_STYLE= new ConfigAttribute<>();
+	public static final ConfigAttribute<Style> CONVERSION_ERROR_STYLE= new ConfigAttribute<>();
 
 	/**
 	 * The configuration attribute for the style that should be used on just in time validation error
@@ -79,13 +79,13 @@ public interface EditConfigAttributes {
 	 * Note: Currently this configuration attribute is only evaluated by the TextCellEditor in combination
 	 * 		 with the RenderErrorHandling for just in time validation error rendering. 
 	 */
-	public static final ConfigAttribute<IStyle> VALIDATION_ERROR_STYLE= new ConfigAttribute<>();
+	public static final ConfigAttribute<Style> VALIDATION_ERROR_STYLE= new ConfigAttribute<>();
 	
 	/**
 	 * The configuration attribute to specify if cell editors should be opened inline or in a dialog.
 	 * If this configuration is not set, the editors will open inline, unless the editors themself
 	 * specify different behaviour.
-	 * @see ICellEditor#openInline(IConfigRegistry configRegistry, List configLabels) 
+	 * @see ICellEditor#openInline(ConfigRegistry configRegistry, List configLabels) 
 	 */
 	public static final ConfigAttribute<Boolean> OPEN_IN_DIALOG= new ConfigAttribute<>();
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditConfigHelper.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditConfigHelper.java
index 13e59737..f12609c6 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditConfigHelper.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditConfigHelper.java
@@ -15,36 +15,36 @@ package org.eclipse.statet.ecommons.waltable.edit;
 
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.config.ConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
 import org.eclipse.statet.ecommons.waltable.edit.config.LoggingErrorHandling;
 import org.eclipse.statet.ecommons.waltable.edit.editor.IEditErrorHandler;
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
 
 
 /**
- * Helper class that will retrieve edit configuration values out of the {@link IConfigRegistry}.
+ * Helper class that will retrieve edit configuration values out of the {@link ConfigRegistry}.
  */
 public class EditConfigHelper {
 
 	/**
 	 * Searches for the registered {@link IEditErrorHandler} that should be used by this editor.
-	 * @param configRegistry The {@link ConfigRegistry} of the NatTable instance this editor is connected to.
+	 * @param configRegistry The {@link BasicConfigRegistry} of the NatTable instance this editor is connected to.
 	 * @param configAttribute The config attribute specifying if the {@link IEditErrorHandler} for conversion
 	 * 			or validation errors is requested.
 	 * @param configLabels The config labels attached to the cell this editor is opened for, needed to 
-	 * 			find the registered {@link IEditErrorHandler} in {@link ConfigRegistry}.
-	 * @return The registered {@link IEditErrorHandler} out of the specified {@link ConfigRegistry} for
+	 * 			find the registered {@link IEditErrorHandler} in {@link BasicConfigRegistry}.
+	 * @return The registered {@link IEditErrorHandler} out of the specified {@link BasicConfigRegistry} for
 	 * 			the config attribute and config labels, or the {@link LoggingErrorHandling} if no other
 	 * 			{@link IEditErrorHandler} is registered.
 	 * @see EditConfigAttributes#CONVERSION_ERROR_HANDLER
 	 * @see EditConfigAttributes#VALIDATION_ERROR_HANDLER
 	 */
 	public static IEditErrorHandler getEditErrorHandler(
-			final IConfigRegistry configRegistry, final ConfigAttribute<IEditErrorHandler> configAttribute, final List<String> configLabels) {
+			final ConfigRegistry configRegistry, final ConfigAttribute<IEditErrorHandler> configAttribute, final List<String> configLabels) {
 		
-		IEditErrorHandler errorHandler= configRegistry.getConfigAttribute(configAttribute, DisplayMode.EDIT, configLabels);
+		IEditErrorHandler errorHandler= configRegistry.getAttribute(configAttribute, DisplayMode.EDIT, configLabels);
 		if (errorHandler == null) {
 			//set LoggingErrorHandling as default
 			errorHandler= new LoggingErrorHandling();
@@ -61,8 +61,8 @@ public class EditConfigHelper {
 	 * <p>There might be editors that are only able to be opened in a dialog. These implementations
 	 * need to override this method to always return <code>false</code>, so the editor never
 	 * gets opened inline.</p>
-	 * @param configRegistry The {@link IConfigRegistry} to retrieve the configuration for
-	 * 			inline/dialog editing out of. Needed here because the instance {@link IConfigRegistry}
+	 * @param configRegistry The {@link ConfigRegistry} to retrieve the configuration for
+	 * 			inline/dialog editing out of. Needed here because the instance {@link ConfigRegistry}
 	 * 			might not be set on calling this method.
 	 * @param configLabels The labels out of the LabelStack of the cell whose editor should be activated.
 	 * 			Needed here because this method needs to be called prior to activation to determine
@@ -71,8 +71,8 @@ public class EditConfigHelper {
 	 * 			if not.
 	 * @see EditConfigAttributes#OPEN_IN_DIALOG
 	 */
-	public static boolean openInline(final IConfigRegistry configRegistry, final List<String> configLabels) {
-		final Boolean openInDialog= configRegistry.getConfigAttribute(
+	public static boolean openInline(final ConfigRegistry configRegistry, final List<String> configLabels) {
+		final Boolean openInDialog= configRegistry.getAttribute(
 				EditConfigAttributes.OPEN_IN_DIALOG, DisplayMode.EDIT, configLabels);
 		return (openInDialog == null || !openInDialog);
 	}
@@ -85,8 +85,8 @@ public class EditConfigHelper {
 	 * the configuration attribute {@link EditConfigAttributes#SUPPORT_MULTI_EDIT}. 
 	 * <p>You should consider returning <code>false</code> e.g. if the update operation is complex or 
 	 * you use conditional validation, where a value is validated against another value in the data model.
-	 * @param configRegistry The {@link IConfigRegistry} to retrieve the configuration for
-	 * 			multi edit support out of. Needed here because the instance {@link IConfigRegistry}
+	 * @param configRegistry The {@link ConfigRegistry} to retrieve the configuration for
+	 * 			multi edit support out of. Needed here because the instance {@link ConfigRegistry}
 	 * 			might not be set on calling this method.
 	 * @param configLabels The labels out of the LabelStack of the cell whose editor should be activated.
 	 * 			Needed here because this method needs to be called prior to activation to determine
@@ -95,8 +95,8 @@ public class EditConfigHelper {
 	 * 			if the multi editing of this kind of cell editor is not supported.
 	 * @see EditConfigAttributes#SUPPORT_MULTI_EDIT
 	 */
-	public static boolean supportMultiEdit(final IConfigRegistry configRegistry, final List<String> configLabels) {
-		final Boolean supportMultiEdit= configRegistry.getConfigAttribute(
+	public static boolean supportMultiEdit(final ConfigRegistry configRegistry, final List<String> configLabels) {
+		final Boolean supportMultiEdit= configRegistry.getAttribute(
 				EditConfigAttributes.SUPPORT_MULTI_EDIT, DisplayMode.EDIT, configLabels);
 		return (supportMultiEdit == null || supportMultiEdit);
 	}
@@ -112,8 +112,8 @@ public class EditConfigHelper {
 	 * <p>
 	 * Note: It only makes sense to call this method if the editor is already activated. Calling this
 	 * 		 method on an editor that has not been activated already will lead to exceptions.</p>
-	 * @param configRegistry The {@link IConfigRegistry} to retrieve the configuration for
-	 * 			multi edit support out of. Needed here because the instance {@link IConfigRegistry}
+	 * @param configRegistry The {@link ConfigRegistry} to retrieve the configuration for
+	 * 			multi edit support out of. Needed here because the instance {@link ConfigRegistry}
 	 * 			might not be set on calling this method.
 	 * @param configLabels The labels out of the LabelStack of the cell whose editor should be activated.
 	 * 			Needed here because this method needs to be called prior to activation to determine
@@ -122,8 +122,8 @@ public class EditConfigHelper {
 	 * 			commit, <code>false</code> if not.
 	 * @see EditConfigAttributes#OPEN_ADJACENT_EDITOR
 	 */
-	public static boolean openAdjacentEditor(final IConfigRegistry configRegistry, final List<String> configLabels) {
-		final Boolean openAdjacentEditor= configRegistry.getConfigAttribute(
+	public static boolean openAdjacentEditor(final ConfigRegistry configRegistry, final List<String> configLabels) {
+		final Boolean openAdjacentEditor= configRegistry.getAttribute(
 				EditConfigAttributes.OPEN_ADJACENT_EDITOR, DisplayMode.EDIT, configLabels);
 		return (openAdjacentEditor != null && openAdjacentEditor);
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditController.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditController.java
index 19af7736..4ce8fb7c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditController.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditController.java
@@ -20,18 +20,19 @@ import java.util.List;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.jface.window.Window;
+import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
 import org.eclipse.statet.ecommons.waltable.edit.gui.CellEditDialogFactory;
 import org.eclipse.statet.ecommons.waltable.edit.gui.ICellEditDialog;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
@@ -52,29 +53,29 @@ public class EditController {
 	 * 			<code>cell.getDataValue()</code>, but for the special case that an editor
 	 * 			should be activated pressing a letter or digit key on the current selection,
 	 * 			the initial value should be the Character representing that key.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of the
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of the
 	 * 			current NatTable instance the command should be executed for.
 	 * 			This is necessary because the edit controllers in the current architecture
 	 * 			are not aware of the instance they are running in.
 	 */
 	public static void editCell(
-			final ILayerCell cell, final Composite parent, 
-			final Object initialCanonicalValue, final IConfigRegistry configRegistry) {
+			final LayerCell cell, final Composite parent, 
+			final Object initialCanonicalValue, final ConfigRegistry configRegistry) {
 		
 		try {
 			//determine the position of the cell to put into edit mode
 			final LRectangle cellBounds= cell.getBounds();
-			final ILayer layer= cell.getLayer();
+			final Layer layer= cell.getLayer();
 			
 			final long columnPosition= cell.getColumnPosition();
 			final long rowPosition= cell.getRowPosition();
 
 			//read the configuration for the specified cell for
 			//- which editor to use for that cell
-			final List<String> configLabels= cell.getConfigLabels().getLabels();
+			final List<String> configLabels= cell.getLabels().getLabels();
 			
 			//check which editor to use
-			final ICellEditor cellEditor= configRegistry.getConfigAttribute(
+			final ICellEditor cellEditor= configRegistry.getAttribute(
 					EditConfigAttributes.CELL_EDITOR, DisplayMode.EDIT, configLabels);
 			
 			if (cellEditor.openInline(configRegistry, configLabels)) {
@@ -84,7 +85,7 @@ public class EditController {
 						columnPosition,
 						rowPosition);
 				
-				org.eclipse.swt.graphics.Rectangle editorBounds= SWTUtil.toSWT(
+				Rectangle editorBounds= SwtUtils.toSWT(
 								layer.getLayerPainter().adjustCellBounds(
 						columnPosition, rowPosition, 
 						new LRectangle(cellBounds.x, cellBounds.y, cellBounds.width, cellBounds.height)));
@@ -111,7 +112,7 @@ public class EditController {
 				}
 			}
 			else {
-				final List<ILayerCell> cells= new ArrayList<>();
+				final List<LayerCell> cells= new ArrayList<>();
 				cells.add(cell);
 				editCells(cells, parent, initialCanonicalValue, configRegistry);
 			}
@@ -140,15 +141,15 @@ public class EditController {
 	 * 			control. Needed because for multi cell editing or editor activation by
 	 * 			letter/digit key will result in a different value to populate for some 
 	 * 			editors than populating the value out of the cell/data model directly.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of 
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of 
 	 * 			the current NatTable instance the command should be executed for. This is 
 	 * 			necessary because the edit controllers in the current architecture are not 
 	 * 			aware of the instance they are running in and therefore it is needed for 
 	 * 			activation of editors.
 	 */
 	public static void editCells(
-			final Collection<ILayerCell> cells, final Composite parent, 
-			final Object initialCanonicalValue, final IConfigRegistry configRegistry) {
+			final Collection<LayerCell> cells, final Composite parent, 
+			final Object initialCanonicalValue, final ConfigRegistry configRegistry) {
 		
 		if (cells != null && !cells.isEmpty()) {
 			//get the editor to use, because the editor contains information if
@@ -156,10 +157,10 @@ public class EditController {
 			//Note: this works because previous to calling this method it is checked
 			//		if all cells have the same editor configured. Otherwise this method
 			//		will have serious issues further on.
-			final ICellEditor cellEditor= configRegistry.getConfigAttribute(
+			final ICellEditor cellEditor= configRegistry.getAttribute(
 					EditConfigAttributes.CELL_EDITOR, 
 					DisplayMode.EDIT, 
-					cells.iterator().next().getConfigLabels().getLabels());
+					cells.iterator().next().getLabels().getLabels());
 
 			if (cells.size() == 1 || 
 					(cells.size() > 1 && supportMultiEdit(cells, cellEditor, configRegistry))) {
@@ -174,12 +175,12 @@ public class EditController {
 					final int returnValue= dialog.open();
 					
 					if (returnValue == Window.OK) {
-						for (final ILayerCell selectedCell : cells) {
+						for (final LayerCell selectedCell : cells) {
 							Object editorValue= dialog.getCommittedValue();
 							if (!(dialog.getEditType() == EditTypeEnum.SET)) {
 								editorValue= dialog.calculateValue(selectedCell.getDataValue(0, null), editorValue);
 							}
-							final ILayer layer= selectedCell.getLayer();
+							final Layer layer= selectedCell.getLayer();
 							
 							layer.doCommand(new UpdateDataCommand(
 									layer, selectedCell.getColumnPosition(), selectedCell.getRowPosition(), editorValue));
@@ -193,7 +194,7 @@ public class EditController {
 					//this only works for editors that have no interactive control for
 					//editing, like for example the CheckBoxCellEditor that directly
 					//changes the value and closes right away.
-					for (final ILayerCell cell : cells) {
+					for (final LayerCell cell : cells) {
 						final ICellEditHandler editHandler= new InlineEditHandler(
 								cell.getLayer(),
 								cell.getColumnPosition(),
@@ -218,7 +219,7 @@ public class EditController {
 	 * all cells are checked to be sure.
 	 * @param cells The selected cells that should be multi edited.
 	 * @param cellEditor The cell editor that is the same for every cell.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of 
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of 
 	 * 			the current NatTable instance the command should be executed for. This is 
 	 * 			necessary because the edit controllers in the current architecture are not 
 	 * 			aware of the instance they are running in and therefore it is needed for 
@@ -226,9 +227,9 @@ public class EditController {
 	 * @return <code>true</code> if the editor supports multi edit for all selected cells,
 	 * 			<code>false</code> if at least one cell does specify to not support multi edit.
 	 */
-	private static boolean supportMultiEdit(final Collection<ILayerCell> cells, final ICellEditor cellEditor, final IConfigRegistry configRegistry) {
-		for (final ILayerCell cell : cells) {
-			if (!cellEditor.supportMultiEdit(configRegistry, cell.getConfigLabels().getLabels())) {
+	private static boolean supportMultiEdit(final Collection<LayerCell> cells, final ICellEditor cellEditor, final ConfigRegistry configRegistry) {
+		for (final LayerCell cell : cells) {
+			if (!cellEditor.supportMultiEdit(configRegistry, cell.getLabels().getLabels())) {
 				return false;
 			}
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditSelectionCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditSelectionCommand.java
index c6633019..a6879890 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditSelectionCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditSelectionCommand.java
@@ -15,8 +15,8 @@ package org.eclipse.statet.ecommons.waltable.edit;
 
 import org.eclipse.swt.widgets.Composite;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
 
 
 /**
@@ -28,13 +28,13 @@ import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 public class EditSelectionCommand extends AbstractContextFreeCommand {
 	
 	/**
-	 * The {@link IConfigRegistry} containing the configuration of the current NatTable 
+	 * The {@link ConfigRegistry} containing the configuration of the current NatTable 
 	 * instance the command should be executed for.
 	 * <p>
 	 * This is necessary because the edit controllers in the current architecture
 	 * are not aware of the instance they are running in.
 	 */
-	private final IConfigRegistry configRegistry;
+	private final ConfigRegistry configRegistry;
 	/**
 	 * The Character represented by the key that was typed in case this command
 	 * should be executed because of typing a letter or digit key. Can be <code>null</code> 
@@ -49,18 +49,18 @@ public class EditSelectionCommand extends AbstractContextFreeCommand {
 
 	/**
 	 * @param parent The parent Composite, needed for the creation of the editor control.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of the
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of the
 	 * 			current NatTable instance the command should be executed for.
 	 * 			This is necessary because the edit controllers in the current architecture
 	 * 			are not aware of the instance they are running in.
 	 */
-	public EditSelectionCommand(final Composite parent, final IConfigRegistry configRegistry) {
+	public EditSelectionCommand(final Composite parent, final ConfigRegistry configRegistry) {
 		this(parent, configRegistry, null);
 	}
 
 	/**
 	 * @param parent The parent Composite, needed for the creation of the editor control.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of the
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of the
 	 * 			current NatTable instance the command should be executed for.
 	 * 			This is necessary because the edit controllers in the current architecture
 	 * 			are not aware of the instance they are running in.
@@ -69,17 +69,17 @@ public class EditSelectionCommand extends AbstractContextFreeCommand {
 	 * 			if this command should be executed because of a pressed control key (like F2) or a 
 	 * 			programmatical execution.
 	 */
-	public EditSelectionCommand(final Composite parent, final IConfigRegistry configRegistry, final Character character) {
+	public EditSelectionCommand(final Composite parent, final ConfigRegistry configRegistry, final Character character) {
 		this.parent= parent;
 		this.configRegistry= configRegistry;
 		this.character= character;
 	}
 
 	/**
-	 * @return The {@link IConfigRegistry} containing the configuration of the current NatTable 
+	 * @return The {@link ConfigRegistry} containing the configuration of the current NatTable 
 	 * 			instance the command should be executed for.
 	 */
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getConfigRegistry() {
 		return this.configRegistry;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditSelectionCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditSelectionCommandHandler.java
index 165f8bb1..7fcbb866 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditSelectionCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditSelectionCommandHandler.java
@@ -17,11 +17,11 @@ import java.util.Collection;
 
 import org.eclipse.swt.widgets.Composite;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 
 
 /**
@@ -46,21 +46,21 @@ public class EditSelectionCommandHandler extends AbstractLayerCommandHandler<Edi
 	@Override
     public boolean doCommand(final EditSelectionCommand command) {
 		final Composite parent= command.getParent();
-		final IConfigRegistry configRegistry= command.getConfigRegistry();
+		final ConfigRegistry configRegistry= command.getConfigRegistry();
 		final Character initialValue= command.getCharacter();
 		
 		if (EditUtils.allCellsEditable(this.selectionLayer, configRegistry)
 				&& EditUtils.isEditorSame(this.selectionLayer, configRegistry)
 				&& EditUtils.isConverterSame(this.selectionLayer, configRegistry)) {
 			//check how many cells are selected
-			final Collection<ILayerCell> selectedCells= this.selectionLayer.getSelectedCells();
+			final Collection<LayerCell> selectedCells= this.selectionLayer.getSelectedCells();
 			if (selectedCells.size() == 1) {
 				//editing is triggered by key for a single cell
 				//we need to fire the InlineCellEditEvent here because we don't know the correct bounds
 				//of the cell to edit inline corresponding to the NatTable. On firing the event, a
 				//translation process is triggered, converting the information to the correct values
 				//needed for inline editing
-				final ILayerCell cell= selectedCells.iterator().next();
+				final LayerCell cell= selectedCells.iterator().next();
 				this.selectionLayer.fireLayerEvent(
 						new InlineCellEditEvent(
 								this.selectionLayer, 
@@ -73,7 +73,7 @@ public class EditSelectionCommandHandler extends AbstractLayerCommandHandler<Edi
 				//determine the initial value
 				Object initialEditValue= initialValue;
 				if (initialValue == null && EditUtils.isValueSame(this.selectionLayer)) {
-					final ILayerCell cell= selectedCells.iterator().next();
+					final LayerCell cell= selectedCells.iterator().next();
 					initialEditValue= cell.getDataValue(0, null);
 				}
 				
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditUtils.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditUtils.java
index edf365e5..43b85ece 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditUtils.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/EditUtils.java
@@ -19,15 +19,15 @@ import java.util.List;
 import java.util.Set;
 
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.config.IEditableRule;
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 
 
 /**
@@ -41,7 +41,7 @@ public class EditUtils {
 	 * @return The last cell of the current selection in the specified {@link SelectionLayer}.
 	 * 			Will return <code>null</code> if there is no selection.
 	 */
-	public static ILayerCell getLastSelectedCell(final SelectionLayer selectionLayer) {
+	public static LayerCell getLastSelectedCell(final SelectionLayer selectionLayer) {
 		final PositionCoordinate selectionAnchor= selectionLayer.getSelectionAnchor();
 		return selectionLayer.getCellByPosition(selectionAnchor.columnPosition, selectionAnchor.rowPosition);
 	}
@@ -49,16 +49,16 @@ public class EditUtils {
 	/**
 	 * 
 	 * @param selectionLayer The {@link SelectionLayer} to retrieve the current selection from.
-	 * @param configRegistry The {@link IConfigRegistry} needed to access the configured
+	 * @param configRegistry The {@link ConfigRegistry} needed to access the configured
 	 * 			{@link ICellEditor}.
 	 * @return The {@link ICellEditor} of the last cell of the current selection in the specified
 	 * 			{@link SelectionLayer}. Will return <code>null</code> if there is no selection.
 	 */
-	public static ICellEditor getLastSelectedCellEditor(final SelectionLayer selectionLayer, final IConfigRegistry configRegistry) {
-		final ILayerCell lastSelectedCell= EditUtils.getLastSelectedCell(selectionLayer);
+	public static ICellEditor getLastSelectedCellEditor(final SelectionLayer selectionLayer, final ConfigRegistry configRegistry) {
+		final LayerCell lastSelectedCell= EditUtils.getLastSelectedCell(selectionLayer);
 		if (lastSelectedCell != null) {
-			final List<String> lastSelectedCellLabelsArray= lastSelectedCell.getConfigLabels().getLabels();
-			return configRegistry.getConfigAttribute(
+			final List<String> lastSelectedCellLabelsArray= lastSelectedCell.getLabels().getLabels();
+			return configRegistry.getAttribute(
 					EditConfigAttributes.CELL_EDITOR, DisplayMode.EDIT, lastSelectedCellLabelsArray);
 		}
 		return null;
@@ -67,16 +67,16 @@ public class EditUtils {
 	/**
 	 * For every cell that is selected it is checked whether the cell is editable or not.
 	 * @param selectionLayer The {@link SelectionLayer} to retrieve the current selection.
-	 * @param configRegistry The {@link IConfigRegistry} needed to access the configured
+	 * @param configRegistry The {@link ConfigRegistry} needed to access the configured
 	 * 			{@link IEditableRule}s.
 	 * @return <code>true</code> if all selected cells are editable, <code>false</code> if
 	 * 			at least one cell is not editable.
 	 */
-	public static boolean allCellsEditable(final SelectionLayer selectionLayer, final IConfigRegistry configRegistry) {
-		final Collection<ILayerCell> selectedCells= selectionLayer.getSelectedCells();
-		for (final ILayerCell layerCell : selectedCells) {
-			final LabelStack labelStack= layerCell.getConfigLabels();
-			final IEditableRule editableRule= configRegistry.getConfigAttribute(
+	public static boolean allCellsEditable(final SelectionLayer selectionLayer, final ConfigRegistry configRegistry) {
+		final Collection<LayerCell> selectedCells= selectionLayer.getSelectedCells();
+		for (final LayerCell layerCell : selectedCells) {
+			final LabelStack labelStack= layerCell.getLabels();
+			final IEditableRule editableRule= configRegistry.getAttribute(
 					EditConfigAttributes.CELL_EDITABLE_RULE, 
 					DisplayMode.EDIT, labelStack.getLabels());
 			
@@ -93,18 +93,18 @@ public class EditUtils {
 	 * Note: The coordinates need to be related to the given SelectionLayer, otherwise
 	 * 		 the wrong cell will be used for the check.
 	 * @param selectionLayer The {@link SelectionLayer} to check the cell coordinates against.
-	 * @param configRegistry The {@link IConfigRegistry} needed to access the configured
+	 * @param configRegistry The {@link ConfigRegistry} needed to access the configured
 	 * 			{@link IEditableRule}s.
 	 * @param cellCoords The coordinates of the cell to check the editable state, related to 
 	 * 			the given {@link SelectionLayer}
 	 * @return <code>true</code> if the cell is editable, <code>false</code> if not
 	 */
 	public static boolean isCellEditable(
-			final SelectionLayer selectionLayer, final IConfigRegistry configRegistry, final PositionCoordinate cellCoords){
-		final ILayerCell layerCell= selectionLayer.getCellByPosition(cellCoords.columnPosition, cellCoords.rowPosition);
-		final LabelStack labelStack= layerCell.getConfigLabels();
+			final SelectionLayer selectionLayer, final ConfigRegistry configRegistry, final PositionCoordinate cellCoords){
+		final LayerCell layerCell= selectionLayer.getCellByPosition(cellCoords.columnPosition, cellCoords.rowPosition);
+		final LabelStack labelStack= layerCell.getLabels();
 		
-		final IEditableRule editableRule= configRegistry.getConfigAttribute(
+		final IEditableRule editableRule= configRegistry.getAttribute(
 				EditConfigAttributes.CELL_EDITABLE_RULE, 
 				DisplayMode.EDIT, labelStack.getLabels());
 		if (editableRule == null) {
@@ -118,21 +118,21 @@ public class EditUtils {
 	 * Checks if all selected cells have the same {@link ICellEditor} configured. This is needed for 
 	 * the multi edit feature to determine if a multi edit is possible.
 	 * @param selectionLayer The {@link SelectionLayer} to retrieve the current selection.
-	 * @param configRegistry The {@link IConfigRegistry} needed to access the configured
+	 * @param configRegistry The {@link ConfigRegistry} needed to access the configured
 	 * 			{@link ICellEditor}s.
 	 * @return <code>true</code> if all selected cells have the same {@link ICellEditor}
 	 * 			configured, <code>false</code> if at least one cell has another {@link ICellEditor}
 	 * 			configured.
 	 */
-	public static boolean isEditorSame(final SelectionLayer selectionLayer, final IConfigRegistry configRegistry) {
+	public static boolean isEditorSame(final SelectionLayer selectionLayer, final ConfigRegistry configRegistry) {
 		final List<PositionCoordinate> selectedCells= selectionLayer.getSelectedCellPositions();
 		ICellEditor lastSelectedCellEditor= null;
 		for (final PositionCoordinate selectedCell : selectedCells) {
-			final ILayerCell cell= selectionLayer.getCellByPosition(
+			final LayerCell cell= selectionLayer.getCellByPosition(
 					selectedCell.columnPosition, selectedCell.rowPosition);
-			final ICellEditor cellEditor= configRegistry.getConfigAttribute(
+			final ICellEditor cellEditor= configRegistry.getAttribute(
 					EditConfigAttributes.CELL_EDITOR,
-					DisplayMode.EDIT, cell.getConfigLabels().getLabels() );
+					DisplayMode.EDIT, cell.getLabels().getLabels() );
 			
 			//The first time we get here we need to remember the editor so further checks can
 			//use it. Getting the editor before by getLastSelectedCellEditor() might cause 
@@ -155,22 +155,22 @@ public class EditUtils {
 	 * Both have a TextCellEditor configured, so if only the editor is checked, the multi edit dialog
 	 * would open. On committing a changed value an error would occur because of wrong conversion.
 	 * @param selectionLayer The {@link SelectionLayer} to retrieve the current selection.
-	 * @param configRegistry The {@link IConfigRegistry} needed to access the configured
+	 * @param configRegistry The {@link ConfigRegistry} needed to access the configured
 	 * 			{@link IDisplayConverter}s.
 	 * @return <code>true</code> if all selected cells have the same {@link IDisplayConverter}
 	 * 			configured, <code>false</code> if at least one cell has another {@link IDisplayConverter}
 	 * 			configured.
 	 */
 	@SuppressWarnings("rawtypes")
-	public static boolean isConverterSame(final SelectionLayer selectionLayer, final IConfigRegistry configRegistry){
+	public static boolean isConverterSame(final SelectionLayer selectionLayer, final ConfigRegistry configRegistry){
 		final List<PositionCoordinate> selectedCells= selectionLayer.getSelectedCellPositions();
 		final Set<Class> converterSet= new HashSet<>();
 		
 		for (final PositionCoordinate selectedCell : selectedCells) {
-			final ILayerCell cell= selectionLayer.getCellByPosition(
+			final LayerCell cell= selectionLayer.getCellByPosition(
 					selectedCell.columnPosition, selectedCell.rowPosition);
-			final IDisplayConverter dataTypeConverter= configRegistry.getConfigAttribute(
-					CellConfigAttributes.DISPLAY_CONVERTER, DisplayMode.EDIT, cell.getConfigLabels().getLabels() );
+			final IDisplayConverter dataTypeConverter= configRegistry.getAttribute(
+					CellConfigAttributes.DISPLAY_CONVERTER, DisplayMode.EDIT, cell.getLabels().getLabels() );
 			if (dataTypeConverter != null) {
 				converterSet.add(dataTypeConverter.getClass());
 			}
@@ -190,8 +190,8 @@ public class EditUtils {
 	 */
 	public static boolean isValueSame(final SelectionLayer selectionLayer) {
 		Object lastSelectedValue= null;
-		final Collection<ILayerCell> selectedCells= selectionLayer.getSelectedCells();
-		for (final ILayerCell layerCell : selectedCells) {
+		final Collection<LayerCell> selectedCells= selectionLayer.getSelectedCells();
+		for (final LayerCell layerCell : selectedCells) {
 			final Object cellValue= layerCell.getDataValue(0, null);
 			if (lastSelectedValue == null) {
 				lastSelectedValue= cellValue;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/ICellEditHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/ICellEditHandler.java
index ac4f0382..672cabff 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/ICellEditHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/ICellEditHandler.java
@@ -13,7 +13,7 @@
 
 package org.eclipse.statet.ecommons.waltable.edit;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
 
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineCellEditEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineCellEditEvent.java
index 7feec798..ac7ea540 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineCellEditEvent.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineCellEditEvent.java
@@ -13,15 +13,17 @@
 
 package org.eclipse.statet.ecommons.waltable.edit;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.swt.widgets.Composite;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
 
 
 /**
@@ -34,13 +36,13 @@ import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
  * these informations are not known and need to be evaluated through the
  * layer event handlers.
  */
-public class InlineCellEditEvent implements ILayerEvent {
+public class InlineCellEditEvent implements LayerEvent {
 
 	/**
 	 * The layer the cellCoordinates rely on. The layer will change on
 	 * event processing to always match the translated coordinates.
 	 */
-	private ILayer layer;
+	private Layer layer;
 	/**
 	 * The coordinates of the cell to edit for the set layer.
 	 */
@@ -50,12 +52,12 @@ public class InlineCellEditEvent implements ILayerEvent {
 	 */
 	private final Composite parent;
 	/**
-	 * The {@link IConfigRegistry} containing the configuration of the
+	 * The {@link ConfigRegistry} containing the configuration of the
 	 * current NatTable instance the command should be executed for.
 	 * This is necessary because the edit controllers in the current architecture
 	 * are not aware of the instance they are running in.
 	 */
-	private final IConfigRegistry configRegistry;
+	private final ConfigRegistry configRegistry;
 	/**
 	 * The value that should be put to the activated editor control.
 	 */
@@ -66,14 +68,14 @@ public class InlineCellEditEvent implements ILayerEvent {
 	 * @param layer The layer the cellCoordinates rely on.
 	 * @param cellCoordinate The coordinates of the cell to edit for the set layer.
 	 * @param parent The parent Composite, needed for the creation of the editor control.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of the
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of the
 	 * 			current NatTable instance the command should be executed for.
 	 * 			This is necessary because the edit controllers in the current architecture
 	 * 			are not aware of the instance they are running in.
 	 * @param initialValue The value that should be put to the activated editor control. 
 	 */
-	public InlineCellEditEvent(final ILayer layer, final PositionCoordinate cellCoordinate, final Composite parent, 
-			final IConfigRegistry configRegistry, final Object initialValue) {
+	public InlineCellEditEvent(final Layer layer, final PositionCoordinate cellCoordinate, final Composite parent, 
+			final ConfigRegistry configRegistry, final Object initialValue) {
 		
 		this.layer= layer;
 		this.cellCoordinate= cellCoordinate;
@@ -83,7 +85,13 @@ public class InlineCellEditEvent implements ILayerEvent {
 	}
 	
 	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
+	public @Nullable InlineCellEditEvent toLayer(final Layer targetLayer) {
+		final InlineCellEditEvent event= new InlineCellEditEvent(this.layer,
+				new PositionCoordinate(this.cellCoordinate), this.parent, this.configRegistry, this.initialValue);
+		return (event.convertToLocal(targetLayer)) ? event : null;
+	}
+	
+	private boolean convertToLocal(final Layer localLayer) {
 		this.cellCoordinate.columnPosition= localLayer.getDim(HORIZONTAL).underlyingToLocalPosition(
 				this.layer.getDim(HORIZONTAL), this.cellCoordinate.columnPosition );
 		if (this.cellCoordinate.columnPosition < 0 || this.cellCoordinate.columnPosition >= localLayer.getColumnCount()) {
@@ -99,7 +107,8 @@ public class InlineCellEditEvent implements ILayerEvent {
 		this.layer= localLayer;
 		return true;
 	}
-
+	
+	
 	/**
 	 * @return The column position of the cell to edit.
 	 */
@@ -122,12 +131,12 @@ public class InlineCellEditEvent implements ILayerEvent {
 	}
 	
 	/**
-	 * @return The {@link IConfigRegistry} containing the configuration of the
+	 * @return The {@link ConfigRegistry} containing the configuration of the
 	 * 			current NatTable instance the command should be executed for.
 	 * 			This is necessary because the edit controllers in the current architecture
 	 * 			are not aware of the instance they are running in.
 	 */
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getConfigRegistry() {
 		return this.configRegistry;
 	}
 	
@@ -138,9 +147,4 @@ public class InlineCellEditEvent implements ILayerEvent {
 		return this.initialValue;
 	}
 	
-	@Override
-	public InlineCellEditEvent cloneEvent() {
-		return new InlineCellEditEvent(this.layer, new PositionCoordinate(this.cellCoordinate), this.parent, this.configRegistry, this.initialValue);
-	}
-	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineCellEditEventHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineCellEditEventHandler.java
index 3c6079e0..4e1c4d2a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineCellEditEventHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineCellEditEventHandler.java
@@ -13,9 +13,12 @@
 
 package org.eclipse.statet.ecommons.waltable.edit;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEventHandler;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerListener;
 
 
 /**
@@ -25,33 +28,36 @@ import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEventHandler;
  * @see InlineCellEditEvent
  * @see EditSelectionCommandHandler
  */
-public class InlineCellEditEventHandler implements ILayerEventHandler<InlineCellEditEvent> {
+@NonNullByDefault
+public class InlineCellEditEventHandler implements LayerListener {
+	
 	
 	/**
 	 * The layer this event handler is associated with. Needed for the conversion of 
 	 * cell position coordinates.Usually this is a grid layer because this is the main 
 	 * cause for this event handler is needed.
 	 */
-	private final ILayer layer;
-
+	private final Layer layer;
+	
+	
 	/**
 	 * @param layer The layer this event handler is associated with. Needed for 
 	 * 			the conversion of cell position coordinates.
 	 */
-	public InlineCellEditEventHandler(final ILayer layer) {
+	public InlineCellEditEventHandler(final Layer layer) {
 		this.layer= layer;
 	}
-
-	@Override
-	public Class<InlineCellEditEvent> getLayerEventClass() {
-		return InlineCellEditEvent.class;
-	}
-
+	
+	
 	@Override
-	public void handleLayerEvent(final InlineCellEditEvent event) {
-		if (event.convertToLocal(this.layer)) {
-			final ILayerCell cell= this.layer.getCellByPosition(event.getColumnPosition(), event.getRowPosition());
-			EditController.editCell(cell, event.getParent(), event.getInitialValue(), event.getConfigRegistry());
+	public void handleLayerEvent(final LayerEvent event) {
+		if (event instanceof InlineCellEditEvent) {
+			final var editEvent= (InlineCellEditEvent)event.toLayer(this.layer);
+			if (editEvent != null) {
+				final LayerCell cell= this.layer.getCellByPosition(editEvent.getColumnPosition(), editEvent.getRowPosition());
+				EditController.editCell(cell, editEvent.getParent(), editEvent.getInitialValue(), editEvent.getConfigRegistry());
+			}
 		}
 	}
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineEditHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineEditHandler.java
index 79dd635b..35e16bd6 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineEditHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/InlineEditHandler.java
@@ -13,9 +13,9 @@
 
 package org.eclipse.statet.ecommons.waltable.edit;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.selection.SelectRelativeCellCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectRelativeCellCommand;
 
 
 /**
@@ -26,10 +26,10 @@ import org.eclipse.statet.ecommons.waltable.selection.SelectRelativeCellCommand;
 public class InlineEditHandler implements ICellEditHandler {
 
 	/**
-	 * The {@link ILayer} to which the column and row positions are related to
+	 * The {@link Layer} to which the column and row positions are related to
 	 * 			and on which the update command should be executed
 	 */
-	private final ILayer layer;
+	private final Layer layer;
 	/**
 	 * The column position of the cell that is edited
 	 */
@@ -41,12 +41,12 @@ public class InlineEditHandler implements ICellEditHandler {
 
 	/**
 	 * 
-	 * @param layer The {@link ILayer} to which the column and row positions are related to
+	 * @param layer The {@link Layer} to which the column and row positions are related to
 	 * 			and on which the update command should be executed
 	 * @param columnPosition The column position of the cell that is edited
 	 * @param rowPosition The row position of the cell that is edited
 	 */
-	public InlineEditHandler(final ILayer layer, final long columnPosition, final long rowPosition) {
+	public InlineEditHandler(final Layer layer, final long columnPosition, final long rowPosition) {
 		this.layer= layer;
 		this.columnPosition= columnPosition;
 		this.rowPosition= rowPosition;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/UpdateDataCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/UpdateDataCommand.java
index 0df4bbc3..320770fb 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/UpdateDataCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/UpdateDataCommand.java
@@ -14,7 +14,7 @@
 package org.eclipse.statet.ecommons.waltable.edit;
 
 import org.eclipse.statet.ecommons.waltable.command.AbstractPositionCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 /**
@@ -29,7 +29,7 @@ public class UpdateDataCommand extends AbstractPositionCommand {
 
 	/**
 	 * Create a new {@link UpdateDataCommand} based on the specified information.
-	 * @param layer The {@link ILayer} to which the columnPosition and rowPosition are resolved
+	 * @param layer The {@link Layer} to which the columnPosition and rowPosition are resolved
 	 * 			to. This is needed to support conversion of column and row positions from this
 	 * 			layer to NatTable coordinates, which may be different e.g. in case of grid
 	 * 			composition.
@@ -37,7 +37,7 @@ public class UpdateDataCommand extends AbstractPositionCommand {
 	 * @param rowPosition The row position of the value to update.
 	 * @param newValue The value to update the data model value to.
 	 */
-	public UpdateDataCommand(final ILayer layer, final long columnPosition, final long rowPosition, final Object newValue) {
+	public UpdateDataCommand(final Layer layer, final long columnPosition, final long rowPosition, final Object newValue) {
 		super(layer, columnPosition, rowPosition);
 		this.newValue= newValue;
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/UpdateDataCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/UpdateDataCommandHandler.java
index f3237964..018c8567 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/UpdateDataCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/UpdateDataCommandHandler.java
@@ -16,16 +16,16 @@ package org.eclipse.statet.ecommons.waltable.edit;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.CellVisualChangeEvent;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.CellVisualChangeEvent;
+import org.eclipse.statet.ecommons.waltable.data.core.DataLayer;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
 /**
- * {@link ILayerCommandHandler} that handles {@link UpdateDataCommand}s by updating
+ * {@link LayerCommandHandler} that handles {@link UpdateDataCommand}s by updating
  * the data model. It is usually directly registered to the {@link DataLayer} this
  * command handler is associated with.
  */
@@ -54,7 +54,7 @@ public class UpdateDataCommandHandler extends AbstractLayerCommandHandler<Update
 		try {
 			final long columnPosition= command.getColumnPosition();
 			final long rowPosition= command.getRowPosition();
-			final IDataProvider dataProvider= this.dataLayer.getDataProvider();
+			final DataProvider dataProvider= this.dataLayer.getDataProvider();
 			final Object oldValue= dataProvider.getDataValue(columnPosition, rowPosition, 0, null);
 			final Object newValue= command.getNewValue();
 			if ((oldValue != null) ? !oldValue.equals(newValue) : null != newValue)  {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/CellEditDragMode.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/CellEditDragMode.java
index 7accd827..4cbbfbfc 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/CellEditDragMode.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/CellEditDragMode.java
@@ -17,7 +17,7 @@ import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
 import org.eclipse.statet.ecommons.waltable.edit.EditCellCommand;
-import org.eclipse.statet.ecommons.waltable.selection.action.CellSelectionDragMode;
+import org.eclipse.statet.ecommons.waltable.selection.ui.action.CellSelectionDragMode;
 
 
 /**
@@ -81,7 +81,7 @@ public class CellEditDragMode extends CellSelectionDragMode {
 		}
 		
 		natTable.doCommand(new EditCellCommand(natTable,
-				natTable.getConfigRegistry(),
+				natTable.getStyleRegistry(),
 				natTable.getCellByPosition(columnPosition, rowPosition) ));
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/KeyEditAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/KeyEditAction.java
index c68ac79a..b8f67cf9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/KeyEditAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/KeyEditAction.java
@@ -38,7 +38,7 @@ public class KeyEditAction implements IKeyAction {
 	public void run(final NatTable natTable, final KeyEvent event) {
 		natTable.doCommand(new EditSelectionCommand(
 						natTable, 
-						natTable.getConfigRegistry(), 
+						natTable.getStyleRegistry(), 
 						convertCharToCharacterObject(event) ));
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/MouseEditAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/MouseEditAction.java
index ce3ed448..22210f1b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/MouseEditAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/MouseEditAction.java
@@ -44,7 +44,7 @@ public class MouseEditAction implements IMouseClickAction {
 		}
 		
 		natTable.doCommand(new EditCellCommand(natTable,
-				natTable.getConfigRegistry(),
+				natTable.getStyleRegistry(),
 				natTable.getCellByPosition(columnPosition, rowPosition) ));
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/ToggleCheckBoxColumnAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/ToggleCheckBoxColumnAction.java
index 08b049da..ce845cdc 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/ToggleCheckBoxColumnAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/action/ToggleCheckBoxColumnAction.java
@@ -16,9 +16,9 @@ package org.eclipse.statet.ecommons.waltable.edit.action;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerUtils;
 import org.eclipse.statet.ecommons.waltable.edit.UpdateDataCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LayerUtil;
 import org.eclipse.statet.ecommons.waltable.painter.cell.ColumnHeaderCheckBoxPainter;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 
@@ -26,9 +26,9 @@ import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 public class ToggleCheckBoxColumnAction implements IMouseAction {
 
 	private final ColumnHeaderCheckBoxPainter columnHeaderCheckBoxPainter;
-	private final ILayer bodyDataLayer;
+	private final Layer bodyDataLayer;
 
-	public ToggleCheckBoxColumnAction(final ColumnHeaderCheckBoxPainter columnHeaderCheckBoxPainter, final ILayer bodyDataLayer) {
+	public ToggleCheckBoxColumnAction(final ColumnHeaderCheckBoxPainter columnHeaderCheckBoxPainter, final Layer bodyDataLayer) {
 		this.columnHeaderCheckBoxPainter= columnHeaderCheckBoxPainter;
 		this.bodyDataLayer= bodyDataLayer;
 	}
@@ -36,9 +36,9 @@ public class ToggleCheckBoxColumnAction implements IMouseAction {
 	@Override
 	public void run(final NatTable natTable, final MouseEvent event) {
 		final long sourceColumnPosition= natTable.getColumnPositionByX(event.x);
-		final long columnPosition= LayerUtil.convertColumnPosition(natTable, sourceColumnPosition, this.bodyDataLayer);
+		final long columnPosition= LayerUtils.convertColumnPosition(natTable, sourceColumnPosition, this.bodyDataLayer);
 		
-		final long checkedCellsCount= this.columnHeaderCheckBoxPainter.getCheckedCellsCount(columnPosition, natTable.getConfigRegistry());
+		final long checkedCellsCount= this.columnHeaderCheckBoxPainter.getCheckedCellsCount(columnPosition, natTable.getStyleRegistry());
 		final boolean targetState= checkedCellsCount < this.bodyDataLayer.getRowCount();
 		
 		for (long rowPosition= 0; rowPosition < this.bodyDataLayer.getRowCount(); rowPosition++) {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/DefaultEditBindings.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/DefaultEditBindings.java
index 2fd26d11..ec6495ea 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/DefaultEditBindings.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/DefaultEditBindings.java
@@ -21,7 +21,7 @@ import org.eclipse.statet.ecommons.waltable.edit.action.CellEditDragMode;
 import org.eclipse.statet.ecommons.waltable.edit.action.KeyEditAction;
 import org.eclipse.statet.ecommons.waltable.edit.action.MouseEditAction;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 import org.eclipse.statet.ecommons.waltable.painter.cell.CheckBoxPainter;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.CellEditorMouseEventMatcher;
@@ -36,7 +36,7 @@ import org.eclipse.statet.ecommons.waltable.ui.matcher.MouseEventMatcher;
  * Default configuration for edit related bindings. Adds bindings that support opening
  * cell editors via keypress and mouse click.
  * <p>
- * By default {@link GridRegion#BODY} is used for the matchers to evaluate if an editor 
+ * By default {@link GridLabels#BODY} is used for the matchers to evaluate if an editor 
  * should be activated. By doing this only the editing in the body layer stack of a grid
  * is enabled.
  * </p>
@@ -62,19 +62,19 @@ public class DefaultEditBindings extends AbstractUiBindingConfiguration {
 		uiBindingRegistry.registerKeyBinding(new LetterOrDigitKeyEventMatcher(SWT.MOD2), new KeyEditAction());
 		
 		uiBindingRegistry.registerSingleClickBinding(
-				new CellEditorMouseEventMatcher(GridRegion.BODY),
+				new CellEditorMouseEventMatcher(GridLabels.BODY),
 				new MouseEditAction());
 		
 		uiBindingRegistry.registerMouseDragMode(
-				new CellEditorMouseEventMatcher(GridRegion.BODY),
+				new CellEditorMouseEventMatcher(GridLabels.BODY),
 				new CellEditDragMode());
 
 		uiBindingRegistry.registerFirstSingleClickBinding(
-                new CellPainterMouseEventMatcher(GridRegion.BODY, MouseEventMatcher.LEFT_BUTTON, CheckBoxPainter.class),
+                new CellPainterMouseEventMatcher(GridLabels.BODY, MouseEventMatcher.LEFT_BUTTON, CheckBoxPainter.class),
                 new MouseEditAction());
 		
 		uiBindingRegistry.registerFirstMouseDragMode(
-                new CellPainterMouseEventMatcher(GridRegion.BODY, MouseEventMatcher.LEFT_BUTTON, CheckBoxPainter.class),
+                new CellPainterMouseEventMatcher(GridLabels.BODY, MouseEventMatcher.LEFT_BUTTON, CheckBoxPainter.class),
 				new CellEditDragMode());
 
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/DefaultEditConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/DefaultEditConfiguration.java
index b1f3c2bc..143d16e4 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/DefaultEditConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/DefaultEditConfiguration.java
@@ -14,14 +14,14 @@
 package org.eclipse.statet.ecommons.waltable.edit.config;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractLayerConfiguration;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.config.IEditableRule;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.AbstractLayer;
 import org.eclipse.statet.ecommons.waltable.data.validate.DefaultDataValidator;
 import org.eclipse.statet.ecommons.waltable.edit.EditCellCommandHandler;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 import org.eclipse.statet.ecommons.waltable.edit.InlineCellEditEventHandler;
 import org.eclipse.statet.ecommons.waltable.edit.editor.TextCellEditor;
-import org.eclipse.statet.ecommons.waltable.layer.AbstractLayer;
 
 
 /**
@@ -50,10 +50,10 @@ public class DefaultEditConfiguration extends AbstractLayerConfiguration<Abstrac
 	}
 	
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
-		configRegistry.registerConfigAttribute(EditConfigAttributes.CELL_EDITABLE_RULE, IEditableRule.NEVER_EDITABLE);
-		configRegistry.registerConfigAttribute(EditConfigAttributes.CELL_EDITOR, new TextCellEditor());
-		configRegistry.registerConfigAttribute(EditConfigAttributes.DATA_VALIDATOR, new DefaultDataValidator());
+	public void configureRegistry(final ConfigRegistry configRegistry) {
+		configRegistry.registerAttribute(EditConfigAttributes.CELL_EDITABLE_RULE, IEditableRule.NEVER_EDITABLE);
+		configRegistry.registerAttribute(EditConfigAttributes.CELL_EDITOR, new TextCellEditor());
+		configRegistry.registerAttribute(EditConfigAttributes.DATA_VALIDATOR, new DefaultDataValidator());
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/RenderErrorHandling.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/RenderErrorHandling.java
index 682fa6a3..79406233 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/RenderErrorHandling.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/config/RenderErrorHandling.java
@@ -17,13 +17,13 @@ import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.widgets.Control;
 
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.edit.editor.AbstractEditErrorHandler;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ControlDecorationProvider;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
 import org.eclipse.statet.ecommons.waltable.edit.editor.IEditErrorHandler;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
-import org.eclipse.statet.ecommons.waltable.style.Style;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -36,10 +36,10 @@ public class RenderErrorHandling extends AbstractEditErrorHandler {
 	/**
 	 * The default error styling used for rendering an error.
 	 */
-	protected IStyle defaultErrorStyle;
+	protected Style defaultErrorStyle;
 	{
-        this.defaultErrorStyle= new Style();
-        this.defaultErrorStyle.setAttributeValue(CellStyleAttributes.FOREGROUND_COLOR, GUIHelper.COLOR_RED);
+        this.defaultErrorStyle= new BasicStyle();
+        this.defaultErrorStyle.setAttributeValue(CellStyling.FOREGROUND_COLOR, GUIHelper.COLOR_RED);
 	}
 	
 	/**
@@ -60,7 +60,7 @@ public class RenderErrorHandling extends AbstractEditErrorHandler {
 	/**
 	 * The style that should be used to render an error.
 	 */
-	protected IStyle errorStyle;
+	protected Style errorStyle;
 	/**
 	 * The decoration provider that should be used for decorating the
 	 * editor control on error.
@@ -157,9 +157,9 @@ public class RenderErrorHandling extends AbstractEditErrorHandler {
 			this.originalFont= editorControl.getFont();
 			
 			//set the rendering information out of the error style
-			editorControl.setBackground(this.errorStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR));
-			editorControl.setForeground(this.errorStyle.getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR));
-			editorControl.setFont(this.errorStyle.getAttributeValue(CellStyleAttributes.FONT));
+			editorControl.setBackground(this.errorStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR));
+			editorControl.setForeground(this.errorStyle.getAttributeValue(CellStyling.FOREGROUND_COLOR));
+			editorControl.setFont(this.errorStyle.getAttributeValue(CellStyling.FONT));
 			
 			if (this.decorationProvider != null) {
 				this.decorationProvider.showDecoration();
@@ -173,7 +173,7 @@ public class RenderErrorHandling extends AbstractEditErrorHandler {
 	 * @param errorStyle The style that should be used to render an error.
 	 * 			Supported style attributes are foreground color, background color and font.
 	 */
-	public void setErrorStyle(final IStyle errorStyle) {
+	public void setErrorStyle(final Style errorStyle) {
 		this.errorStyle= errorStyle != null ? errorStyle : this.defaultErrorStyle;
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/AbstractCellEditor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/AbstractCellEditor.java
index 87e57096..0d419b02 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/AbstractCellEditor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/AbstractCellEditor.java
@@ -29,8 +29,13 @@ import org.eclipse.swt.widgets.Control;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.style.RegistryStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.data.convert.ConversionFailedException;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
 import org.eclipse.statet.ecommons.waltable.data.validate.IDataValidator;
@@ -41,11 +46,6 @@ import org.eclipse.statet.ecommons.waltable.edit.EditConfigHelper;
 import org.eclipse.statet.ecommons.waltable.edit.EditMode;
 import org.eclipse.statet.ecommons.waltable.edit.EditSelectionCommand;
 import org.eclipse.statet.ecommons.waltable.edit.ICellEditHandler;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleProxy;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
@@ -83,7 +83,7 @@ public abstract class AbstractCellEditor implements ICellEditor {
 	 * the editor control supports further styles, this needs to be specified
 	 * be the ICellEditor implementation itself.
 	 */
-	protected IStyle cellStyle;
+	protected Style cellStyle;
 	/**
 	 * The {@link IDisplayConverter} that should be used to convert the input value 
 	 * to the canonical value and vice versa.
@@ -104,7 +104,7 @@ public abstract class AbstractCellEditor implements ICellEditor {
 	/**
 	 * The cell whose editor should be activated.
 	 */
-	protected ILayerCell layerCell;
+	protected LayerCell layerCell;
 	/**
 	 * The {@link LabelStack} of the cell whose editor should be activated.
 	 */
@@ -118,12 +118,12 @@ public abstract class AbstractCellEditor implements ICellEditor {
 	 */
 	protected IEditErrorHandler validationEditErrorHandler;
 	/**
-	 * The {@link IConfigRegistry} containing the configuration of the
+	 * The {@link ConfigRegistry} containing the configuration of the
 	 * current NatTable instance. This is necessary because the editors in 
 	 * the current architecture are not aware of the NatTable instance they 
 	 * are running in.
 	 */
-	protected IConfigRegistry configRegistry;
+	protected ConfigRegistry configRegistry;
 	
 	/**
 	 * The {@link FocusListener} that will be added to the created editor control
@@ -139,7 +139,7 @@ public abstract class AbstractCellEditor implements ICellEditor {
 	
 	@Override
 	public final Control activateCell(final Composite parent, final Object originalCanonicalValue, final EditMode editMode, 
-			final ICellEditHandler editHandler, final ILayerCell cell, final IConfigRegistry configRegistry) {
+			final ICellEditHandler editHandler, final LayerCell cell, final ConfigRegistry configRegistry) {
 
 		this.closed= false;
 		this.parent= parent;
@@ -147,12 +147,13 @@ public abstract class AbstractCellEditor implements ICellEditor {
 		this.editMode= editMode;
 		this.layerCell= cell;
 		this.configRegistry= configRegistry;
-		this.labelStack= cell.getConfigLabels();
+		this.labelStack= cell.getLabels();
 		final List<String> configLabels= this.labelStack.getLabels();
-		this.displayConverter= configRegistry.getConfigAttribute(
+		this.displayConverter= configRegistry.getAttribute(
 				CellConfigAttributes.DISPLAY_CONVERTER, DisplayMode.EDIT, configLabels);
-		this.cellStyle= new CellStyleProxy(configRegistry, DisplayMode.EDIT, configLabels);
-		this.dataValidator= configRegistry.getConfigAttribute(
+		this.cellStyle= new RegistryStyle(configRegistry, CellConfigAttributes.CELL_STYLE,
+				DisplayMode.EDIT, configLabels);
+		this.dataValidator= configRegistry.getAttribute(
 				EditConfigAttributes.DATA_VALIDATOR, DisplayMode.EDIT, configLabels);
 		
 		this.conversionEditErrorHandler= EditConfigHelper.getEditErrorHandler(
@@ -165,7 +166,7 @@ public abstract class AbstractCellEditor implements ICellEditor {
 	
 	/**
 	 * This method will be called by {@link AbstractCellEditor#activateCell(Composite, Object, EditMode, 
-	 * ICellEditHandler, ILayerCell, IConfigRegistry)} after initializing the activation values and before
+	 * ICellEditHandler, LayerCell, ConfigRegistry)} after initializing the activation values and before
 	 * adding the default listeners. In this method the underlying editor control should be created and
 	 * initialized, hiding default configuration from editor implementors.
 	 * @param parent The parent Composite, needed for the creation of the editor control.
@@ -176,7 +177,7 @@ public abstract class AbstractCellEditor implements ICellEditor {
 	
 	
 	/**
-	 * @see ILayerCell#getColumnPosition()
+	 * @see LayerCell#getColumnPosition()
 	 */
 	@Override
 	public long getColumnPosition() {
@@ -184,7 +185,7 @@ public abstract class AbstractCellEditor implements ICellEditor {
 	}
 
 	/**
-	 * @see ILayerCell#getRowPosition()
+	 * @see LayerCell#getRowPosition()
 	 */
 	@Override
 	public long getRowPosition() {
@@ -386,12 +387,12 @@ public abstract class AbstractCellEditor implements ICellEditor {
 	}
 	
 	@Override
-	public boolean openInline(final IConfigRegistry configRegistry, final List<String> configLabels) {
+	public boolean openInline(final ConfigRegistry configRegistry, final List<String> configLabels) {
 		return EditConfigHelper.openInline(configRegistry, configLabels);
 	}
 	
 	@Override
-	public boolean supportMultiEdit(final IConfigRegistry configRegistry, final List<String> configLabels) {
+	public boolean supportMultiEdit(final ConfigRegistry configRegistry, final List<String> configLabels) {
 		return EditConfigHelper.supportMultiEdit(configRegistry, configLabels);				
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/CheckBoxCellEditor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/CheckBoxCellEditor.java
index 3f0cac63..db63dc94 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/CheckBoxCellEditor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/CheckBoxCellEditor.java
@@ -104,7 +104,7 @@ public class CheckBoxCellEditor extends AbstractCellEditor {
 			if (value instanceof Boolean) {
 				this.checked= ((Boolean)value).booleanValue();
 			} else if (value instanceof String) {
-				this.checked= Boolean.valueOf((String) value).booleanValue();
+				this.checked= Boolean.parseBoolean((String) value);
 			} else {
 				this.checked= false;
 			}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/ControlDecorationProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/ControlDecorationProvider.java
index d0afc196..8fee8863 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/ControlDecorationProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/ControlDecorationProvider.java
@@ -20,6 +20,7 @@ import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.PaintEvent;
 import org.eclipse.swt.events.PaintListener;
 import org.eclipse.swt.graphics.Image;
+import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Control;
 
 
@@ -171,8 +172,8 @@ public class ControlDecorationProvider {
 						
 						controlToDecorate.removePaintListener(this);
 						int position= SWT.TOP;
-						final org.eclipse.swt.graphics.Rectangle textBounds= controlToDecorate.getBounds();
-						final org.eclipse.swt.graphics.Rectangle parentClientArea= controlToDecorate.getParent().getClientArea();
+						final Rectangle textBounds= controlToDecorate.getBounds();
+						final Rectangle parentClientArea= controlToDecorate.getParent().getClientArea();
 						if ((parentClientArea.x + parentClientArea.width) > (textBounds.x + textBounds.width + errorImage.getBounds().width)) {
 							position |= SWT.RIGHT;
 						} else {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/DateCellEditor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/DateCellEditor.java
index fb324e46..3a6e28ca 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/DateCellEditor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/DateCellEditor.java
@@ -23,9 +23,9 @@ import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.DateTime;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
 import org.eclipse.statet.ecommons.waltable.edit.EditMode;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
 
 
 /**
@@ -133,9 +133,9 @@ public class DateCellEditor extends AbstractCellEditor {
 		final DateTime dateControl= new DateTime(parent, SWT.DATE | SWT.DROP_DOWN);
 		
 		//set style information configured in the associated cell style
-		dateControl.setBackground(this.cellStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR));
-		dateControl.setForeground(this.cellStyle.getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR));
-		dateControl.setFont(this.cellStyle.getAttributeValue(CellStyleAttributes.FONT));
+		dateControl.setBackground(this.cellStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR));
+		dateControl.setForeground(this.cellStyle.getAttributeValue(CellStyling.FOREGROUND_COLOR));
+		dateControl.setFont(this.cellStyle.getAttributeValue(CellStyling.FONT));
 		
 		//add a key listener that will commit or close the editor for special key strokes
 		dateControl.addKeyListener(new KeyAdapter() {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/ICellEditor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/ICellEditor.java
index 98cdcb2f..98408f3d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/ICellEditor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/ICellEditor.java
@@ -19,15 +19,15 @@ import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
 import org.eclipse.statet.ecommons.waltable.data.validate.IDataValidator;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 import org.eclipse.statet.ecommons.waltable.edit.EditController;
 import org.eclipse.statet.ecommons.waltable.edit.EditMode;
 import org.eclipse.statet.ecommons.waltable.edit.ICellEditHandler;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.IMouseEventMatcher;
 
 
@@ -54,7 +54,7 @@ public interface ICellEditor {
 	 * 			than rendering the editor on a subdialog.
 	 * @param editHandler The {@link ICellEditHandler} that will be used on commit.
 	 * @param cell The cell whose corresponding editor should be activated.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of the
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of the
 	 * 			current NatTable instance.
 	 * 			This is necessary because the editors in the current architecture
 	 * 			are not aware of the NatTable instance they are running in.
@@ -65,8 +65,8 @@ public interface ICellEditor {
 			Object originalCanonicalValue,
 			EditMode editMode,
 			ICellEditHandler editHandler,
-			ILayerCell cell,
-			IConfigRegistry configRegistry
+			LayerCell cell,
+			ConfigRegistry configRegistry
 	);
 	
 	
@@ -234,8 +234,8 @@ public interface ICellEditor {
 	 * <p>There might be editors that are only able to be opened in a dialog. These implementations
 	 * need to override this method to always return <code>false</code>, so the editor never
 	 * gets opened inline.</p>
-	 * @param configRegistry The {@link IConfigRegistry} to retrieve the configuration for
-	 * 			inline/dialog editing out of. Needed here because the instance {@link IConfigRegistry}
+	 * @param configRegistry The {@link ConfigRegistry} to retrieve the configuration for
+	 * 			inline/dialog editing out of. Needed here because the instance {@link ConfigRegistry}
 	 * 			might not be set on calling this method.
 	 * @param configLabels The labels out of the LabelStack of the cell whose editor should be activated.
 	 * 			Needed here because this method needs to be called prior to activation to determine
@@ -244,7 +244,7 @@ public interface ICellEditor {
 	 * 			if not.
 	 * @see EditConfigAttributes#OPEN_IN_DIALOG
 	 */
-	boolean openInline(IConfigRegistry configRegistry, List<String> configLabels);
+	boolean openInline(ConfigRegistry configRegistry, List<String> configLabels);
 	
 	/**
 	 * Determines whether this editor supports multi edit behaviour or not. If this method returns
@@ -254,8 +254,8 @@ public interface ICellEditor {
 	 * the configuration attribute {@link EditConfigAttributes#SUPPORT_MULTI_EDIT}. 
 	 * <p>You should consider returning <code>false</code> e.g. if the update operation is complex or 
 	 * you use conditional validation, where a value is validated against another value in the data model.
-	 * @param configRegistry The {@link IConfigRegistry} to retrieve the configuration for
-	 * 			multi edit support out of. Needed here because the instance {@link IConfigRegistry}
+	 * @param configRegistry The {@link ConfigRegistry} to retrieve the configuration for
+	 * 			multi edit support out of. Needed here because the instance {@link ConfigRegistry}
 	 * 			might not be set on calling this method.
 	 * @param configLabels The labels out of the LabelStack of the cell whose editor should be activated.
 	 * 			Needed here because this method needs to be called prior to activation to determine
@@ -264,7 +264,7 @@ public interface ICellEditor {
 	 * 			if the multi editing of this kind of cell editor is not supported.
 	 * @see EditConfigAttributes#SUPPORT_MULTI_EDIT
 	 */
-	boolean supportMultiEdit(IConfigRegistry configRegistry, List<String> configLabels);
+	boolean supportMultiEdit(ConfigRegistry configRegistry, List<String> configLabels);
 	
 	/**
 	 * This is a very special configuration to tell whether an ICellEditor should open a multi
@@ -327,8 +327,8 @@ public interface ICellEditor {
 	 * closing the editor, it needs to be ensured that the listeners are removed again. Otherwise
 	 * the listeners would be added again everytime the editor is activated.</li>
 	 * </ol>
-	 * This method will be called automatically by {@link EditController#editCell(ILayerCell, Composite, 
-	 * Object, IConfigRegistry)}.
+	 * This method will be called automatically by {@link EditController#editCell(LayerCell, Composite, 
+	 * Object, ConfigRegistry)}.
 	 */
 	void addEditorControlListeners();
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/IEditErrorHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/IEditErrorHandler.java
index 30fb3122..2d11b9af 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/IEditErrorHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/IEditErrorHandler.java
@@ -13,14 +13,14 @@
 
 package org.eclipse.statet.ecommons.waltable.edit.editor;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 
 
 /**
  * An {@link IEditErrorHandler} will be used if on data conversion or validation 
  * while editing via {@link ICellEditor} an error occurs. Such a handler is usually
- * registered in the {@link IConfigRegistry}, using the {@link EditConfigAttributes}.
+ * registered in the {@link ConfigRegistry}, using the {@link EditConfigAttributes}.
  * <p>
  * For some {@link ICellEditor}s they are also used for just in time conversion/validation
  * to render the wrong input immediately for feedback to the user. This is done e.g. in
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/PasswordCellEditor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/PasswordCellEditor.java
index eae99622..f76dee99 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/PasswordCellEditor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/PasswordCellEditor.java
@@ -17,16 +17,16 @@ import org.eclipse.swt.SWT;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Text;
 
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
 import org.eclipse.statet.ecommons.waltable.edit.EditMode;
 import org.eclipse.statet.ecommons.waltable.painter.cell.PasswordTextPainter;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
 
 
 /**
  * Specialised {@link TextCellEditor} that sets the echo char of the text control used by
  * this editor to a configured character. You can configure the echo character by setting
- * the attribute {@link CellStyleAttributes#PASSWORD_ECHO_CHAR} to the cell style to use. 
+ * the attribute {@link CellStyling#PASSWORD_ECHO_CHAR} to the cell style to use. 
  * If there is no echo character configured, the bullet character will be used.
  * 
  * <p>As the anonymization of the inserted value only relates to the {@link Text} control,
@@ -64,7 +64,7 @@ public class PasswordCellEditor extends TextCellEditor {
 				parent, style);
 		
 		//search for the configured echo character within the ConfigRegistry
-		final Character configEchoChar= this.cellStyle.getAttributeValue(CellStyleAttributes.PASSWORD_ECHO_CHAR);
+		final Character configEchoChar= this.cellStyle.getAttributeValue(CellStyling.PASSWORD_ECHO_CHAR);
 		//set the echo char of the Text control to the configured one or if there is
 		//none configured, set the bullet char
 		textControl.setEchoChar(configEchoChar != null ? configEchoChar : '\u2022');
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/TableCellEditor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/TableCellEditor.java
index e8681cea..658884cf 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/TableCellEditor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/TableCellEditor.java
@@ -45,16 +45,16 @@ import org.eclipse.swt.widgets.TableItem;
 import org.eclipse.swt.widgets.Text;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.data.convert.ConversionFailedException;
 import org.eclipse.statet.ecommons.waltable.data.validate.ValidationFailedException;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 import org.eclipse.statet.ecommons.waltable.edit.EditMode;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
-import org.eclipse.statet.ecommons.waltable.style.Style;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -132,10 +132,7 @@ public class TableCellEditor extends AbstractCellEditor {
 						return Messages.getString("AbstractCellEditor.validationFailure"); //$NON-NLS-1$
 					}
 				}
-				catch (final ConversionFailedException e) {
-					return e.getLocalizedMessage();
-				}
-				catch (final ValidationFailedException e) {
+				catch (final ConversionFailedException | ValidationFailedException e) {
 					return e.getLocalizedMessage();
 				}
 			}
@@ -270,7 +267,7 @@ public class TableCellEditor extends AbstractCellEditor {
 		
 		//set style information configured in the associated cell style
 		final Table tableControl= this.viewer.getTable();
-		tableControl.setBackground(this.cellStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR));
+		tableControl.setBackground(this.cellStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR));
 		
 		tableControl.setLinesVisible(true);
 		
@@ -626,33 +623,33 @@ public class TableCellEditor extends AbstractCellEditor {
 	 */
 	protected class InternalLabelProvider extends ColumnLabelProvider {
 		
-		private final IStyle normalStyle;
-		private IStyle conversionErrorStyle;
-		private IStyle validationErrorStyle;
+		private final Style normalStyle;
+		private Style conversionErrorStyle;
+		private Style validationErrorStyle;
 		
 		public InternalLabelProvider() {
 			this.normalStyle= TableCellEditor.this.cellStyle;
-			this.conversionErrorStyle= TableCellEditor.this.configRegistry.getConfigAttribute(
+			this.conversionErrorStyle= TableCellEditor.this.configRegistry.getAttribute(
 					EditConfigAttributes.CONVERSION_ERROR_STYLE, 
 					DisplayMode.EDIT, 
 					TableCellEditor.this.labelStack.getLabels());
 			
 			if (this.conversionErrorStyle == null) {
-				this.conversionErrorStyle= new Style();
+				this.conversionErrorStyle= new BasicStyle();
 		        this.conversionErrorStyle.setAttributeValue(
-		        		CellStyleAttributes.FOREGROUND_COLOR, 
+		        		CellStyling.FOREGROUND_COLOR, 
 		        		GUIHelper.COLOR_RED);
 			}
 			
-			this.validationErrorStyle= TableCellEditor.this.configRegistry.getConfigAttribute(
+			this.validationErrorStyle= TableCellEditor.this.configRegistry.getAttribute(
 					EditConfigAttributes.VALIDATION_ERROR_STYLE, 
 					DisplayMode.EDIT, 
 					TableCellEditor.this.labelStack.getLabels());
 			
 			if (this.validationErrorStyle == null) {
-				this.validationErrorStyle= new Style();
+				this.validationErrorStyle= new BasicStyle();
 		        this.validationErrorStyle.setAttributeValue(
-		        		CellStyleAttributes.FOREGROUND_COLOR, 
+		        		CellStyling.FOREGROUND_COLOR, 
 		        		GUIHelper.COLOR_RED);
 			}
 		}
@@ -662,7 +659,7 @@ public class TableCellEditor extends AbstractCellEditor {
 		 * @param element The element for which the style should be searched
 		 * @return The IStyle for the current state of the given element
 		 */
-		public IStyle getActiveCellStyle(final Object element) {
+		public Style getActiveCellStyle(final Object element) {
 			if (!((ValueWrapper)element).isValid()) {
 				return this.validationErrorStyle;
 			}
@@ -694,17 +691,17 @@ public class TableCellEditor extends AbstractCellEditor {
 		
 		@Override
 		public Color getForeground(final Object element) {
-			return getActiveCellStyle(element).getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR);
+			return getActiveCellStyle(element).getAttributeValue(CellStyling.FOREGROUND_COLOR);
 		}
 		
 		@Override
 		public Color getBackground(final Object element) {
-			return getActiveCellStyle(element).getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
+			return getActiveCellStyle(element).getAttributeValue(CellStyling.BACKGROUND_COLOR);
 		}
 		
 		@Override
 		public Font getFont(final Object element) {
-			return getActiveCellStyle(element).getAttributeValue(CellStyleAttributes.FONT);
+			return getActiveCellStyle(element).getAttributeValue(CellStyling.FONT);
 		}
 
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/TextCellEditor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/TextCellEditor.java
index c8c3cb46..c6dcea7f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/TextCellEditor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/editor/TextCellEditor.java
@@ -23,14 +23,14 @@ import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Text;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 import org.eclipse.statet.ecommons.waltable.edit.EditMode;
 import org.eclipse.statet.ecommons.waltable.edit.config.RenderErrorHandling;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
 
 
 /**
@@ -160,7 +160,7 @@ public class TextCellEditor extends AbstractCellEditor {
 		//Note: this is currently only implemented in here, as the TextCellEditor is
 		//		the only editor that supports just in time conversion/validation
 		if (this.inputConversionErrorHandler instanceof RenderErrorHandling) {
-			final IStyle conversionErrorStyle= this.configRegistry.getConfigAttribute(
+			final Style conversionErrorStyle= this.configRegistry.getAttribute(
 					EditConfigAttributes.CONVERSION_ERROR_STYLE, 
 					DisplayMode.EDIT, 
 					this.labelStack.getLabels());
@@ -169,7 +169,7 @@ public class TextCellEditor extends AbstractCellEditor {
 		}
 
 		if (this.inputValidationErrorHandler instanceof RenderErrorHandling) {
-			final IStyle validationErrorStyle= this.configRegistry.getConfigAttribute(
+			final Style validationErrorStyle= this.configRegistry.getAttribute(
 					EditConfigAttributes.VALIDATION_ERROR_STYLE, 
 					DisplayMode.EDIT, 
 					this.labelStack.getLabels());
@@ -219,9 +219,9 @@ public class TextCellEditor extends AbstractCellEditor {
 		final Text textControl= new Text(parent, style);
 		
 		//set style information configured in the associated cell style
-		textControl.setBackground(this.cellStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR));
-		textControl.setForeground(this.cellStyle.getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR));
-		textControl.setFont(this.cellStyle.getAttributeValue(CellStyleAttributes.FONT));
+		textControl.setBackground(this.cellStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR));
+		textControl.setForeground(this.cellStyle.getAttributeValue(CellStyling.FOREGROUND_COLOR));
+		textControl.setFont(this.cellStyle.getAttributeValue(CellStyling.FONT));
 		
 		textControl.setCursor(new Cursor(Display.getDefault(), SWT.CURSOR_IBEAM));
 		
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/AbstractDialogCellEditor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/AbstractDialogCellEditor.java
index 28d44415..b2ebd4f9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/AbstractDialogCellEditor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/AbstractDialogCellEditor.java
@@ -26,8 +26,10 @@ import org.eclipse.swt.widgets.Control;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.data.convert.ConversionFailedException;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
 import org.eclipse.statet.ecommons.waltable.data.validate.IDataValidator;
@@ -40,8 +42,6 @@ import org.eclipse.statet.ecommons.waltable.edit.EditTypeEnum;
 import org.eclipse.statet.ecommons.waltable.edit.ICellEditHandler;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
 import org.eclipse.statet.ecommons.waltable.edit.editor.IEditErrorHandler;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
@@ -70,7 +70,7 @@ public abstract class AbstractDialogCellEditor implements ICellEditor, ICellEdit
 	/**
 	 * The cell whose editor should be activated.
 	 */
-	protected ILayerCell layerCell;
+	protected LayerCell layerCell;
 	/**
 	 * The {@link ICellEditHandler} that will be used on commit.
 	 */
@@ -94,12 +94,12 @@ public abstract class AbstractDialogCellEditor implements ICellEditor, ICellEdit
 	 */
 	protected IEditErrorHandler validationEditErrorHandler;
 	/**
-	 * The {@link IConfigRegistry} containing the configuration of the
+	 * The {@link ConfigRegistry} containing the configuration of the
 	 * current NatTable instance. This is necessary because the editors in 
 	 * the current architecture are not aware of the NatTable instance they 
 	 * are running in.
 	 */
-	protected IConfigRegistry configRegistry;
+	protected ConfigRegistry configRegistry;
 	/**
 	 * Map that contains custom configurations for this {@link CellEditDialog}.
 	 * We do not use the {@link IDialogSettings} provided by JFace, because they are
@@ -139,17 +139,17 @@ public abstract class AbstractDialogCellEditor implements ICellEditor, ICellEdit
 	@Override
 	public Control activateCell(final Composite parent,
 			final Object originalCanonicalValue, final EditMode editMode,
-			final ICellEditHandler editHandler, final ILayerCell cell,
-			final IConfigRegistry configRegistry) {
+			final ICellEditHandler editHandler, final LayerCell cell,
+			final ConfigRegistry configRegistry) {
 
 		this.parent= parent;
 		this.layerCell= cell;
 		this.configRegistry= configRegistry;
 
-		final List<String> configLabels= cell.getConfigLabels().getLabels();
-		this.displayConverter= configRegistry.getConfigAttribute(
+		final List<String> configLabels= cell.getLabels().getLabels();
+		this.displayConverter= configRegistry.getAttribute(
 				CellConfigAttributes.DISPLAY_CONVERTER, DisplayMode.EDIT, configLabels);
-		this.dataValidator= configRegistry.getConfigAttribute(
+		this.dataValidator= configRegistry.getAttribute(
 				EditConfigAttributes.DATA_VALIDATOR, DisplayMode.EDIT, configLabels);
 		
 		this.conversionEditErrorHandler= EditConfigHelper.getEditErrorHandler(
@@ -368,13 +368,13 @@ public abstract class AbstractDialogCellEditor implements ICellEditor, ICellEdit
 	 * @see org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor#openInline(org.eclipse.statet.ecommons.waltable.config.IConfigRegistry, java.util.List)
 	 */
 	@Override
-	public boolean openInline(final IConfigRegistry configRegistry, final List<String> configLabels) {
+	public boolean openInline(final ConfigRegistry configRegistry, final List<String> configLabels) {
 		return false;
 	}
 
 	@Override
-	public boolean supportMultiEdit(final IConfigRegistry configRegistry, final List<String> configLabels) {
-		final Boolean supportMultiEdit= configRegistry.getConfigAttribute(
+	public boolean supportMultiEdit(final ConfigRegistry configRegistry, final List<String> configLabels) {
+		final Boolean supportMultiEdit= configRegistry.getAttribute(
 				EditConfigAttributes.SUPPORT_MULTI_EDIT, DisplayMode.EDIT, configLabels);
 		return (supportMultiEdit == null || supportMultiEdit);
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/CellEditDialog.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/CellEditDialog.java
index 68393142..4e4519b4 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/CellEditDialog.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/CellEditDialog.java
@@ -30,13 +30,13 @@ import org.eclipse.swt.widgets.Label;
 import org.eclipse.swt.widgets.Shell;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.edit.DialogEditHandler;
 import org.eclipse.statet.ecommons.waltable.edit.EditMode;
 import org.eclipse.statet.ecommons.waltable.edit.EditTypeEnum;
 import org.eclipse.statet.ecommons.waltable.edit.ICellEditHandler;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -69,15 +69,15 @@ public class CellEditDialog extends Dialog implements ICellEditDialog {
 	 * The cell that should be edited. Needed because editor activation
 	 * retrieves the configuration for editing directly out of the cell.
 	 */
-	protected final ILayerCell cell;
+	protected final LayerCell cell;
 	
 	/**
-	 * The {@link IConfigRegistry} containing the configuration of the current NatTable 
+	 * The {@link ConfigRegistry} containing the configuration of the current NatTable 
 	 * instance the command should be executed for. This is necessary because the edit 
 	 * controllers in the current architecture are not aware of the instance they are 
 	 * running in and therefore it is needed for activation of editors.
 	 */
-	protected final IConfigRegistry configRegistry;
+	protected final ConfigRegistry configRegistry;
 
 	/**
 	 * Map that contains custom configurations for this {@link CellEditDialog}.
@@ -97,7 +97,7 @@ public class CellEditDialog extends Dialog implements ICellEditDialog {
 	 * 			retrieves the configuration for editing directly out of the cell.
 	 * @param cellEditor The {@link ICellEditor} that will be used as editor control
 	 * 			within the dialog.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of 
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of 
 	 * 			the current NatTable instance the command should be executed for. This is 
 	 * 			necessary because the edit controllers in the current architecture are not 
 	 * 			aware of the instance they are running in and therefore it is needed for 
@@ -105,9 +105,9 @@ public class CellEditDialog extends Dialog implements ICellEditDialog {
 	 */
 	public CellEditDialog(final Shell parentShell,
 			final Object originalCanonicalValue,
-			final ILayerCell cell,
+			final LayerCell cell,
 			final ICellEditor cellEditor,
-			final IConfigRegistry configRegistry) {
+			final ConfigRegistry configRegistry) {
 
 		super(parentShell);
 		this.originalCanonicalValue= originalCanonicalValue;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/CellEditDialogFactory.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/CellEditDialogFactory.java
index 20ed98ed..42c68c1e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/CellEditDialogFactory.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/CellEditDialogFactory.java
@@ -15,13 +15,13 @@ package org.eclipse.statet.ecommons.waltable.edit.gui;
 
 import org.eclipse.swt.widgets.Shell;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.edit.DialogEditHandler;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 import org.eclipse.statet.ecommons.waltable.edit.EditMode;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
 import org.eclipse.statet.ecommons.waltable.tickupdate.ITickUpdateHandler;
 import org.eclipse.statet.ecommons.waltable.tickupdate.TickUpdateConfigAttributes;
 
@@ -48,7 +48,7 @@ public class CellEditDialogFactory {
 	 * @param cell The cell that should be edited. Needed because editor activation
 	 * 			retrieves the configuration for editing directly out of the cell.
 	 * @param cellEditor The cell editor that should be used for multi cell editing.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of 
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of 
 	 * 			the current NatTable instance the command should be executed for. This is 
 	 * 			necessary because the edit controllers in the current architecture are not 
 	 * 			aware of the instance they are running in and therefore it is needed for 
@@ -57,9 +57,9 @@ public class CellEditDialogFactory {
 	 */
 	public static ICellEditDialog createCellEditDialog(final Shell parentShell,
 			final Object originalCanonicalValue,
-			final ILayerCell cell,
+			final LayerCell cell,
 			final ICellEditor cellEditor,
-			final IConfigRegistry configRegistry) {
+			final ConfigRegistry configRegistry) {
 		
 		ICellEditDialog result= null;
 		
@@ -72,10 +72,10 @@ public class CellEditDialogFactory {
 			result= (ICellEditDialog) cellEditor;
 		}
 		else {
-			final ITickUpdateHandler tickUpdateHandler= configRegistry.getConfigAttribute(
+			final ITickUpdateHandler tickUpdateHandler= configRegistry.getAttribute(
 					TickUpdateConfigAttributes.UPDATE_HANDLER, 
 					DisplayMode.EDIT, 
-					cell.getConfigLabels().getLabels());
+					cell.getLabels().getLabels());
 			if (tickUpdateHandler != null && tickUpdateHandler.isApplicableFor(cell.getDataValue(0, null))) {
 				//if a tick update handler is applicable, return the TickUpdateCellEditDialog
 				result= new TickUpdateCellEditDialog(
@@ -88,10 +88,10 @@ public class CellEditDialogFactory {
 		}
 		
 		//check if there are custom edit dialog settings registered
-		result.setDialogSettings(configRegistry.getConfigAttribute(
+		result.setDialogSettings(configRegistry.getAttribute(
 				EditConfigAttributes.EDIT_DIALOG_SETTINGS, 
 				DisplayMode.EDIT, 
-				cell.getConfigLabels().getLabels()));
+				cell.getLabels().getLabels()));
 		
 		return result;
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/ICellEditDialog.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/ICellEditDialog.java
index 5571fa1d..b75fb0a5 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/ICellEditDialog.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/ICellEditDialog.java
@@ -15,7 +15,7 @@ package org.eclipse.statet.ecommons.waltable.edit.gui;
 
 import java.util.Map;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 import org.eclipse.statet.ecommons.waltable.edit.EditTypeEnum;
 
@@ -101,7 +101,7 @@ public interface ICellEditDialog {
 	 * Allows to customize the appearance of the dialog. This method will be called by the
 	 * framework at creation time of the dialog via the {@link CellEditDialogFactory}. 
 	 * <p>
-	 * The map containing the settings can be registered to the {@link IConfigRegistry} for 
+	 * The map containing the settings can be registered to the {@link ConfigRegistry} for 
 	 * the key {@link org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes#EDIT_DIALOG_SETTINGS}. The keys that are valid
 	 * for this map are specified below.
 	 * 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/TickUpdateCellEditDialog.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/TickUpdateCellEditDialog.java
index 65e03282..f8c66c33 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/TickUpdateCellEditDialog.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/edit/gui/TickUpdateCellEditDialog.java
@@ -26,15 +26,15 @@ import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Shell;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.data.validate.IDataValidator;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 import org.eclipse.statet.ecommons.waltable.edit.EditMode;
 import org.eclipse.statet.ecommons.waltable.edit.EditTypeEnum;
 import org.eclipse.statet.ecommons.waltable.edit.editor.AbstractCellEditor;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
 import org.eclipse.statet.ecommons.waltable.tickupdate.ITickUpdateHandler;
 import org.eclipse.statet.ecommons.waltable.tickupdate.TickUpdateConfigAttributes;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
@@ -96,7 +96,7 @@ public class TickUpdateCellEditDialog extends CellEditDialog {
 	 * 			retrieves the configuration for editing directly out of the cell.
 	 * @param cellEditor The {@link ICellEditor} that will be used as editor control
 	 * 			within the dialog.
-	 * @param configRegistry The {@link IConfigRegistry} containing the configuration of 
+	 * @param configRegistry The {@link ConfigRegistry} containing the configuration of 
 	 * 			the current NatTable instance the command should be executed for. This is 
 	 * 			necessary because the edit controllers in the current architecture are not 
 	 * 			aware of the instance they are running in and therefore it is needed for 
@@ -106,18 +106,18 @@ public class TickUpdateCellEditDialog extends CellEditDialog {
 	 */
 	public TickUpdateCellEditDialog(final Shell parentShell,
 			final Object originalCanonicalValue,
-			final ILayerCell cell,
+			final LayerCell cell,
 			final ICellEditor cellEditor,
-			final IConfigRegistry configRegistry,
+			final ConfigRegistry configRegistry,
 			final ITickUpdateHandler tickUpdateHandler) {
 		
 		super(parentShell, originalCanonicalValue, cell, cellEditor, configRegistry);
 		this.tickUpdateHandler= tickUpdateHandler;
 		
-		final Boolean useAdjustByConfig= configRegistry.getConfigAttribute(
+		final Boolean useAdjustByConfig= configRegistry.getAttribute(
 				TickUpdateConfigAttributes.USE_ADJUST_BY, 
 				DisplayMode.EDIT, 
-				cell.getConfigLabels().getLabels());
+				cell.getLabels().getLabels());
 		this.useAdjustBy= useAdjustByConfig != null ? useAdjustByConfig : false;
 	}
 
@@ -141,10 +141,10 @@ public class TickUpdateCellEditDialog extends CellEditDialog {
 				this.cell, 
 				this.configRegistry);
 		
-		this.validator= this.configRegistry.getConfigAttribute(
+		this.validator= this.configRegistry.getAttribute(
 				EditConfigAttributes.DATA_VALIDATOR, 
 				DisplayMode.EDIT, 
-				this.cell.getConfigLabels().getLabels());
+				this.cell.getLabels().getLabels());
 		
 		if (this.cellEditor instanceof AbstractCellEditor) {
 			//need to override the validator because increase decrease adjust don't need to validate immediately
@@ -218,7 +218,7 @@ public class TickUpdateCellEditDialog extends CellEditDialog {
 	@Override
 	public Object calculateValue(final Object currentValue, final Object processValue) {
 		final double delta= processValue instanceof Number 
-				? ((Number)processValue).doubleValue() : Double.valueOf((String)processValue).doubleValue();
+				? ((Number)processValue).doubleValue() : Double.parseDouble((String)processValue);
 		if (this.editType == EditTypeEnum.ADJUST) {
 		    if(delta >= 0) {
 		    	this.editType= EditTypeEnum.INCREASE;
@@ -279,7 +279,7 @@ public class TickUpdateCellEditDialog extends CellEditDialog {
 		}
 
 		@Override
-		public boolean validate(final ILayerCell cell, final IConfigRegistry configRegistry, final Object newValue) {
+		public boolean validate(final LayerCell cell, final ConfigRegistry configRegistry, final Object newValue) {
 			if (TickUpdateCellEditDialog.this.editType == EditTypeEnum.SET) {
 				return this.wrappedValidator.validate(cell, configRegistry, newValue);
 			}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/CompositeFreezeLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/CompositeFreezeLayer.java
deleted file mode 100644
index b67aad22..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/CompositeFreezeLayer.java
+++ /dev/null
@@ -1,198 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.freeze;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
-import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
-
-import java.util.Properties;
-import java.util.StringTokenizer;
-
-import org.eclipse.swt.graphics.Color;
-import org.eclipse.swt.graphics.GC;
-
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.freeze.config.DefaultFreezeGridBindings;
-import org.eclipse.statet.ecommons.waltable.grid.ClientAreaResizeCommand;
-import org.eclipse.statet.ecommons.waltable.grid.layer.DimensionallyDependentLayer;
-import org.eclipse.statet.ecommons.waltable.layer.AbstractLayer;
-import org.eclipse.statet.ecommons.waltable.layer.CompositeLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
-import org.eclipse.statet.ecommons.waltable.viewport.ViewportLayer;
-import org.eclipse.statet.ecommons.waltable.viewport.ViewportSelectDimPositionsCommandHandler;
-
-
-public class CompositeFreezeLayer extends CompositeLayer {
-	
-	
-	private final FreezeLayer freezeLayer;
-	private final ViewportLayer viewportLayer;
-	private final SelectionLayer selectionLayer;
-	
-	
-	public CompositeFreezeLayer(final FreezeLayer freezeLayer, final ViewportLayer viewportLayer, final SelectionLayer selectionLayer) {
-		this(freezeLayer, viewportLayer, selectionLayer, true);
-	}
-	
-	public CompositeFreezeLayer(final FreezeLayer freezeLayer, final ViewportLayer viewportLayer, final SelectionLayer selectionLayer,
-			final boolean useDefaultConfiguration) {
-		super(2, 2);
-		this.freezeLayer= freezeLayer;
-		this.viewportLayer= viewportLayer;
-		this.selectionLayer= selectionLayer;
-		
-		setChildLayer("FROZEN_REGION", freezeLayer, 0, 0); //$NON-NLS-1$
-		setChildLayer("FROZEN_ROW_REGION", new DimensionallyDependentLayer(viewportLayer.getScrollableLayer(), viewportLayer, freezeLayer), 1, 0); //$NON-NLS-1$
-		setChildLayer("FROZEN_COLUMN_REGION", new DimensionallyDependentLayer(viewportLayer.getScrollableLayer(), freezeLayer, viewportLayer), 0, 1); //$NON-NLS-1$
-		setChildLayer("NONFROZEN_REGION", viewportLayer, 1, 1); //$NON-NLS-1$
-		
-		registerCommandHandlers();
-		
-		if (useDefaultConfiguration) {
-			addConfiguration(new DefaultFreezeGridBindings());
-		}
-	}
-	
-	
-	@Override
-	protected ILayerPainter createPainter() {
-		return new FreezableLayerPainter();
-	}
-	
-	
-	public boolean isFrozen() {
-		return this.freezeLayer.isFrozen();
-	}
-	
-	@Override
-	public ILayerPainter getLayerPainter() {
-		return this.layerPainter;
-	}
-	
-	@Override
-	protected void registerCommandHandlers() {
-		registerCommandHandler(new FreezeCommandHandler(this.freezeLayer, this.viewportLayer, this.selectionLayer));
-		
-		final AbstractLayer frozenRowLayer= (AbstractLayer) getChildLayerByLayoutCoordinate(1, 0);
-		frozenRowLayer.registerCommandHandler(new ViewportSelectDimPositionsCommandHandler(
-				frozenRowLayer, VERTICAL ));
-		
-		final AbstractLayer frozenColumnLayer= (AbstractLayer) getChildLayerByLayoutCoordinate(0, 1);
-		frozenColumnLayer.registerCommandHandler(new ViewportSelectDimPositionsCommandHandler(
-				frozenRowLayer, HORIZONTAL ));
-	}
-	
-	
-	@Override
-	public boolean doCommand(final ILayerCommand command) {
-		//if this layer should handle a ClientAreaResizeCommand we have to ensure that
-		//it is only called on the ViewportLayer, as otherwise an undefined behaviour
-		//could occur because the ViewportLayer isn't informed about potential refreshes
-		if (command instanceof ClientAreaResizeCommand) {
-			this.viewportLayer.doCommand(command);
-		}
-		return super.doCommand(command);
-	}
-	
-	
-	// Persistence
-	
-	@Override
-	public void saveState(final String prefix, final Properties properties) {
-		PositionCoordinate coord= this.freezeLayer.getTopLeftPosition();
-		properties.setProperty(prefix + FreezeLayer.PERSISTENCE_TOP_LEFT_POSITION, 
-				coord.columnPosition + IPersistable.VALUE_SEPARATOR + coord.rowPosition);
-		
-		coord= this.freezeLayer.getBottomRightPosition();
-		properties.setProperty(prefix + FreezeLayer.PERSISTENCE_BOTTOM_RIGHT_POSITION, 
-				coord.columnPosition + IPersistable.VALUE_SEPARATOR + coord.rowPosition);
-		
-		super.saveState(prefix, properties);
-	}
-	
-	@Override
-	public void loadState(final String prefix, final Properties properties) {
-		String property= properties.getProperty(prefix + FreezeLayer.PERSISTENCE_TOP_LEFT_POSITION);
-		PositionCoordinate topLeftPosition= null;
-		if (property != null) {
-			final StringTokenizer tok= new StringTokenizer(property, IPersistable.VALUE_SEPARATOR);
-			final String columnPosition= tok.nextToken();
-			final String rowPosition= tok.nextToken();
-			topLeftPosition= new PositionCoordinate(this.freezeLayer, 
-					Long.valueOf(columnPosition), Long.valueOf(rowPosition));
-		}
-		
-		property= properties.getProperty(prefix + FreezeLayer.PERSISTENCE_BOTTOM_RIGHT_POSITION);
-		PositionCoordinate bottomRightPosition= null;
-		if (property != null) {
-			final StringTokenizer tok= new StringTokenizer(property, IPersistable.VALUE_SEPARATOR);
-			final String columnPosition= tok.nextToken();
-			final String rowPosition= tok.nextToken();
-			bottomRightPosition= new PositionCoordinate(this.freezeLayer, 
-					Long.valueOf(columnPosition), Long.valueOf(rowPosition));
-		}
-		
-		//only restore a freeze state if there is one persisted
-		if (topLeftPosition != null && bottomRightPosition != null) {
-			if (topLeftPosition.columnPosition == -1 && topLeftPosition.rowPosition == -1
-					&& bottomRightPosition.columnPosition == -1 && bottomRightPosition.rowPosition == -1) {
-				FreezeHelper.unfreeze(this.freezeLayer, this.viewportLayer);
-			} else {
-				FreezeHelper.freeze(this.freezeLayer, this.viewportLayer, topLeftPosition, bottomRightPosition);
-			}
-		}
-		
-		super.loadState(prefix, properties);
-	}
-	
-	
-	class FreezableLayerPainter extends CompositeLayerPainter {
-		
-		public FreezableLayerPainter() {
-		}
-		
-		@Override
-		public void paintLayer(final ILayer natLayer, final GC gc, final int xOffset, final int yOffset, final org.eclipse.swt.graphics.Rectangle rectangle, final IConfigRegistry configRegistry) {
-			super.paintLayer(natLayer, gc, xOffset, yOffset, rectangle, configRegistry);
-			
-			Color separatorColor= configRegistry.getConfigAttribute(IFreezeConfigAttributes.SEPARATOR_COLOR, DisplayMode.NORMAL);
-			if (separatorColor == null) {
-				separatorColor= GUIHelper.COLOR_BLUE;
-			}
-			
-			gc.setClipping(rectangle);
-			final Color oldFg= gc.getForeground();
-			gc.setForeground(separatorColor);
-			final long freezeWidth= CompositeFreezeLayer.this.freezeLayer.getWidth() - 1;
-			if (freezeWidth > 0) {
-				gc.drawLine(safe(xOffset + freezeWidth), yOffset, safe(xOffset + freezeWidth), safe(yOffset + getHeight() - 1));
-			}
-			final long freezeHeight= CompositeFreezeLayer.this.freezeLayer.getHeight() - 1;
-			if (freezeHeight > 0) {
-				gc.drawLine(xOffset, safe(yOffset + freezeHeight), safe(xOffset + getWidth() - 1), safe(yOffset + freezeHeight));
-			}
-			gc.setForeground(oldFg);
-		}
-		
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeEvent.java
deleted file mode 100644
index 117ef0c7..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeEvent.java
+++ /dev/null
@@ -1,48 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.freeze;
-
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralRefreshEvent;
-
-
-public class FreezeEvent extends StructuralRefreshEvent {
-
-	public FreezeEvent(final ILayer layer) {
-		super(layer);
-	}
-	
-	protected FreezeEvent(final FreezeEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public FreezeEvent cloneEvent() {
-		return new FreezeEvent(this);
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getColumnDiffs() {
-		return null;
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getRowDiffs() {
-		return null;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeEventHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeEventHandler.java
deleted file mode 100644
index 2cfe00ca..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeEventHandler.java
+++ /dev/null
@@ -1,126 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.freeze;
-
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEventHandler;
-import org.eclipse.statet.ecommons.waltable.layer.event.IStructuralChangeEvent;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff;
-
-
-public class FreezeEventHandler implements ILayerEventHandler<IStructuralChangeEvent> {
-
-	private final FreezeLayer freezeLayer;
-	
-	public FreezeEventHandler(final FreezeLayer freezeLayer) {
-		this.freezeLayer= freezeLayer;
-	}
-
-	@Override
-	public Class<IStructuralChangeEvent> getLayerEventClass() {
-		return IStructuralChangeEvent.class;
-	}
-
-	@Override
-	public void handleLayerEvent(final IStructuralChangeEvent event) {
-		final PositionCoordinate topLeftPosition= this.freezeLayer.getTopLeftPosition();
-		final PositionCoordinate bottomRightPosition= this.freezeLayer.getBottomRightPosition();
-		
-		// The handling of diffs have to be in sync with ViewportLayerDim#handleStructuralChanges
-		final Collection<StructuralDiff> columnDiffs= event.getColumnDiffs();
-		if (columnDiffs != null) {
-			int leftOffset= 0;
-			int rightOffset= 0;
-			int freezeMove= 0; // 0= unset, 1 == true, -1 == false
-			
-			for (final StructuralDiff diff : columnDiffs) {
-				final long start= diff.getBeforePositionRange().start;
-				switch (diff.getDiffType()) {
-				case ADD:
-					if (start < topLeftPosition.columnPosition) {
-						leftOffset+= diff.getAfterPositionRange().size();
-					}
-					if (start <= bottomRightPosition.columnPosition
-							|| (freezeMove == 1 && start == bottomRightPosition.columnPosition + 1) ) {
-						rightOffset+= diff.getAfterPositionRange().size();
-					}
-					continue;
-				case DELETE:
-					if (start < topLeftPosition.columnPosition) {
-						leftOffset-= Math.min(diff.getBeforePositionRange().end, topLeftPosition.columnPosition + 1) - start;
-					}
-					if (start <= bottomRightPosition.columnPosition) {
-						rightOffset-= Math.min(diff.getBeforePositionRange().end, bottomRightPosition.columnPosition + 1) - start;
-						if (freezeMove == 0) {
-							freezeMove= 1;
-						}
-					}
-					else {
-						freezeMove= -1;
-					}
-					continue;
-				default:
-					continue;
-				}
-			}
-			
-			topLeftPosition.columnPosition+= leftOffset;
-			bottomRightPosition.columnPosition+= rightOffset;
-		}
-		
-		final Collection<StructuralDiff> rowDiffs= event.getRowDiffs();
-		if (rowDiffs != null) {
-			int leftOffset= 0;
-			int rightOffset= 0;
-			int freezeMove= 0; // 0= unset, 1 == true, -1 == false
-			
-			for (final StructuralDiff diff : rowDiffs) {
-				final long start= diff.getBeforePositionRange().start;
-				switch (diff.getDiffType()) {
-				case ADD:
-					if (start < topLeftPosition.rowPosition) {
-						leftOffset+= diff.getAfterPositionRange().size();
-					}
-					if (start <= bottomRightPosition.rowPosition
-							|| (freezeMove == 1 && start == bottomRightPosition.rowPosition + 1) ) {
-						rightOffset+= diff.getAfterPositionRange().size();
-					}
-					continue;
-				case DELETE:
-					if (start < topLeftPosition.rowPosition) {
-						leftOffset-= Math.min(diff.getBeforePositionRange().end, topLeftPosition.rowPosition + 1) - start;
-					}
-					if (start <= bottomRightPosition.rowPosition) {
-						rightOffset-= Math.min(diff.getBeforePositionRange().end, bottomRightPosition.rowPosition + 1) - start;
-						if (freezeMove == 0) {
-							freezeMove= 1;
-						}
-					}
-					else {
-						freezeMove= -1;
-					}
-					continue;
-				default:
-					continue;
-				}
-			}
-			
-			topLeftPosition.rowPosition+= leftOffset;
-			bottomRightPosition.rowPosition+= rightOffset;
-		}
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/ReorderFrozenAreaCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/ReorderFrozenAreaCommand.java
deleted file mode 100644
index c9e36552..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/ReorderFrozenAreaCommand.java
+++ /dev/null
@@ -1,33 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.freeze;
-
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-public class ReorderFrozenAreaCommand implements ILayerCommand {
-
-	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
-		// TODO Auto-generated method stub
-		return true;
-	}
-	
-	@Override
-	public ReorderFrozenAreaCommand cloneCommand() {
-		return this;
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/ReorderFrozenAreaCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/ReorderFrozenAreaCommandHandler.java
deleted file mode 100644
index baf3e7d7..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/ReorderFrozenAreaCommandHandler.java
+++ /dev/null
@@ -1,32 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.freeze;
-
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-
-
-public class ReorderFrozenAreaCommandHandler extends AbstractLayerCommandHandler<ReorderFrozenAreaCommand> {
-	
-	
-	@Override
-	public boolean doCommand(final ReorderFrozenAreaCommand command) {
-		return false;
-	}
-	
-	@Override
-	public Class<ReorderFrozenAreaCommand> getCommandClass() {
-		return ReorderFrozenAreaCommand.class;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/UnfreezeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/UnfreezeEvent.java
deleted file mode 100644
index 7a87e7a7..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/UnfreezeEvent.java
+++ /dev/null
@@ -1,48 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.freeze;
-
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralRefreshEvent;
-
-
-public class UnfreezeEvent extends StructuralRefreshEvent {
-
-	public UnfreezeEvent(final ILayer layer) {
-		super(layer);
-	}
-	
-	protected UnfreezeEvent(final UnfreezeEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public UnfreezeEvent cloneEvent() {
-		return new UnfreezeEvent(this);
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getColumnDiffs() {
-		return null;
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getRowDiffs() {
-		return null;
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/InitializeGridCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/InitializeGridCommand.java
deleted file mode 100644
index ec1c649b..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/InitializeGridCommand.java
+++ /dev/null
@@ -1,37 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.grid;
-
-import org.eclipse.swt.widgets.Composite;
-
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
-
-
-/**
- * Command that is propagated when NatTable starts up. This gives every layer a
- * chance to initialize itself and compute its structural caches.
- */
-public class InitializeGridCommand extends AbstractContextFreeCommand {
-
-	private final Composite tableComposite;
-
-	public InitializeGridCommand(final Composite tableComposite) {
-		this.tableComposite= tableComposite;
-	}
-
-	public Composite getTableComposite() {
-		return this.tableComposite;
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DefaultBodyDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DefaultBodyDataProvider.java
deleted file mode 100644
index e35e6cd6..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DefaultBodyDataProvider.java
+++ /dev/null
@@ -1,28 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.grid.data;
-
-import java.util.List;
-
-import org.eclipse.statet.ecommons.waltable.data.ListDataProvider;
-import org.eclipse.statet.ecommons.waltable.data.ReflectiveColumnPropertyAccessor;
-
-
-public class DefaultBodyDataProvider<T> extends ListDataProvider<T> {
-
-	public DefaultBodyDataProvider(final List<T> rowData, final String[] propertyNames) {
-		super(rowData, new ReflectiveColumnPropertyAccessor<T>(propertyNames));
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/CornerGridLineCellLayerPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/CornerGridLineCellLayerPainter.java
deleted file mode 100644
index e78fee56..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/CornerGridLineCellLayerPainter.java
+++ /dev/null
@@ -1,122 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.grid.labeled;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
-import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
-
-import org.eclipse.swt.graphics.Color;
-import org.eclipse.swt.graphics.GC;
-import org.eclipse.swt.graphics.Rectangle;
-
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.painter.layer.CellLayerPainter;
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
-
-
-public class CornerGridLineCellLayerPainter extends CellLayerPainter {
-	
-	
-	private final Color gridColor;
-	
-	public CornerGridLineCellLayerPainter(final Color gridColor) {
-		this.gridColor= gridColor;
-	}
-	
-	public CornerGridLineCellLayerPainter() {
-		this.gridColor= GUIHelper.COLOR_GRAY;
-	}
-	
-	
-	public Color getGridColor() {
-		return this.gridColor;
-	}
-	
-	private ILayer getCornerLayer(final ILayer layer) {
-		return layer.getUnderlyingLayerByPosition(0, 0).getUnderlyingLayerByPosition(0, 0);
-	}
-	
-	
-	@Override
-	public void paintLayer(final ILayer natLayer, final GC gc, final int xOffset, final int yOffset, final Rectangle rectangle, final IConfigRegistry configRegistry) {
-		//Draw GridLines
-		drawGridLines(natLayer, gc, rectangle);
-		
-		super.paintLayer(natLayer, gc, xOffset, yOffset, rectangle, configRegistry);
-	}
-	
-	@Override
-	public LRectangle adjustCellBounds(final long columnPosition, final long rowPosition, final LRectangle bounds) {
-		return new LRectangle(bounds.x, bounds.y, bounds.width - 1, bounds.height - 1);
-	}
-	
-	protected void drawGridLines(final ILayer natLayer, final GC gc, final Rectangle rectangle) {
-		gc.setForeground(this.gridColor);
-		
-		drawHorizontalLines(natLayer, gc, rectangle);
-		drawVerticalLines(natLayer, gc, rectangle);
-	}
-	
-	private void drawHorizontalLines(final ILayer natLayer, final GC gc, final Rectangle rectangle) {
-		final int startX, endX;
-		{	final ILayerDim colDim= natLayer.getDim(HORIZONTAL);
-			startX= safe(rectangle.x + colDim.getPositionStart(
-					getCornerLayer(natLayer).getColumnCount() - 1 ) - 1 );
-			endX= safe(rectangle.x + Math.min(colDim.getSize() - 1, rectangle.width));
-		}
-		final ILayerDim dim= natLayer.getDim(VERTICAL);
-		final long lastPosition= getEndPosition(dim, rectangle.y + rectangle.height) - 1;
-		if (startX < endX) {
-			for (long position= dim.getPositionByPixel(rectangle.y); position < lastPosition; position++) {
-				final int size= dim.getPositionSize(position);
-				if (size > 0) {
-					final int y= safe(dim.getPositionStart(position) + dim.getPositionSize(position) - 1);
-					gc.drawLine(startX, y, endX, y);
-				}
-			}
-		}
-		{	final int y= safe(dim.getPositionStart(lastPosition) + dim.getPositionSize(lastPosition) - 1);
-			gc.drawLine(safe(rectangle.x), y, endX, y);
-		}
-	}
-	
-	private void drawVerticalLines(final ILayer natLayer, final GC gc, final Rectangle rectangle) {
-		final int startY, endY;
-		{	final ILayerDim rowDim= natLayer.getDim(VERTICAL);
-			startY= safe(rectangle.y + rowDim.getPositionStart(
-					getCornerLayer(natLayer).getRowCount() - 1 ) - 1 );
-			endY= safe(rectangle.y + Math.min(rowDim.getSize() - 1, rectangle.height));
-		}
-		
-		final ILayerDim dim= natLayer.getDim(HORIZONTAL);
-		final long lastPosition= getEndPosition(dim, rectangle.x + rectangle.width) - 1;
-		if (startY < endY) {
-			for (long position= dim.getPositionByPixel(rectangle.x); position < lastPosition; position++) {
-				final int size= dim.getPositionSize(position);
-				if (size > 0) {
-					final int x= safe(dim.getPositionStart(position) + size - 1);
-					gc.drawLine(x, startY, x, endY);
-				}
-			}
-		}
-		{	final int x= safe(dim.getPositionStart(lastPosition) + dim.getPositionSize(lastPosition) - 1);
-			gc.drawLine(x, safe(rectangle.y), x, endY);
-		}
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/LabelCornerLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/LabelCornerLayer.java
deleted file mode 100644
index 89120139..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/LabelCornerLayer.java
+++ /dev/null
@@ -1,120 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Stephan Wahlbrink and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
- # which is available at https://www.apache.org/licenses/LICENSE-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
- # 
- # Contributors:
- #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.grid.labeled;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
-
-import org.eclipse.core.runtime.IProgressMonitor;
-
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.grid.layer.CornerLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCellDim;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-
-
-public class LabelCornerLayer extends CornerLayer {
-	
-	
-	private final IDataProvider columnHeaderLabelProvider;
-	private final IDataProvider rowHeaderLabelProvider;
-	
-	
-	/**
-	 * @param baseLayer
-	 *            The data provider for this layer
-	 * @param horizontalLayerDependency
-	 *            The layer to link the horizontal dimension to, typically the row header layer
-	 * @param verticalLayerDependency
-	 *            The layer to link the vertical dimension to, typically the column header layer
-	 * @param useDefaultConfiguration
-	 *            If default configuration should be applied to this layer (at moment none)
-	 * @param layerPainter
-	 *            The painter for this layer or <code>null</code> to use the painter of the base layer
-	 */
-	public LabelCornerLayer(final ILayer baseLayer,
-			final ILayer horizontalLayerDependency, final ILayer verticalLayerDependency,
-			final IDataProvider columnHeaderLabelProvider, final IDataProvider rowHeaderLabelProvider,
-			final boolean useDefaultConfiguration, final ILayerPainter layerPainter) {
-		super(baseLayer, horizontalLayerDependency, verticalLayerDependency,
-				useDefaultConfiguration, layerPainter );
-		
-		this.columnHeaderLabelProvider= columnHeaderLabelProvider;
-		this.rowHeaderLabelProvider= rowHeaderLabelProvider;
-	}
-	
-	
-	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
-		final ILayerDim hDim= getDim(HORIZONTAL);
-		final ILayerDim vDim= getDim(VERTICAL);
-		final long columnId= hDim.getPositionId(columnPosition, columnPosition);
-		final long rowId= vDim.getPositionId(rowPosition, rowPosition);
-		
-		final long columnCount= getColumnCount();
-		final long rowCount= getRowCount();
-		if (rowPosition < rowCount - 1) {
-			return new LayerCell(this,
-					new LayerCellDim(HORIZONTAL, columnId, columnPosition, 0, columnCount),
-					new LayerCellDim(VERTICAL, rowId, rowPosition) ) {
-				@Override
-				public LabelStack getConfigLabels() {
-					return new LabelStack(GridRegion.COLUMN_HEADER_LABEL);
-				}
-				@Override
-				public Object getDataValue(final int flags, final IProgressMonitor monitor) {
-					return (LabelCornerLayer.this.columnHeaderLabelProvider != null) ? 
-							LabelCornerLayer.this.columnHeaderLabelProvider.getDataValue(
-									0, getRowPosition(), flags, monitor ) :
-							""; //$NON-NLS-1$
-				}
-			};
-		}
-		else if (columnPosition < columnCount - 1) {
-			return new LayerCell(this,
-					new LayerCellDim(HORIZONTAL, columnId, columnPosition),
-					new LayerCellDim(VERTICAL, rowId, rowPosition) ) {
-				@Override
-				public LabelStack getConfigLabels() {
-					return new LabelStack(GridRegion.ROW_HEADER_LABEL);
-				}
-				@Override
-				public Object getDataValue(final int flags, final IProgressMonitor monitor) {
-					return (LabelCornerLayer.this.rowHeaderLabelProvider != null) ? 
-							LabelCornerLayer.this.rowHeaderLabelProvider.getDataValue(
-									getColumnPosition(), 0, flags, monitor) :
-							""; //$NON-NLS-1$
-				}
-			};
-		}
-		else {
-			return new LayerCell(this,
-					new LayerCellDim(HORIZONTAL, columnId, columnPosition),
-					new LayerCellDim(VERTICAL, rowId, rowPosition) ) {
-				@Override
-				public LabelStack getConfigLabels() {
-					return new LabelStack(GridRegion.HEADER_PLACEHOLDER);
-				}
-			};
-		}
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/CornerLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/CornerLayer.java
deleted file mode 100644
index ab687f25..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/CornerLayer.java
+++ /dev/null
@@ -1,84 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.grid.layer;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
-
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCellDim;
-import org.eclipse.statet.ecommons.waltable.painter.layer.CellLayerPainter;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-
-
-/**
- * Layer for the top left header corner of the grid layer
- */
-public class CornerLayer extends DimensionallyDependentLayer {
-	
-	
-	/**
-	 * Creates a corner header layer using the default configuration and painter
-	 * 
-	 * @param baseLayer
-	 *            The data provider for this layer
-	 * @param horizontalLayerDependency
-	 *            The layer to link the horizontal dimension to, typically the row header layer
-	 * @param verticalLayerDependency
-	 *            The layer to link the vertical dimension to, typically the column header layer
-	 */
-	public CornerLayer(final ILayer baseLayer,
-			final ILayer horizontalLayerDependency, final ILayer verticalLayerDependency) {
-		this(baseLayer, horizontalLayerDependency, verticalLayerDependency, true, new CellLayerPainter());
-	}
-	
-	/**
-	 * @param baseLayer
-	 *            The data provider for this layer
-	 * @param horizontalLayerDependency
-	 *            The layer to link the horizontal dimension to, typically the row header layer
-	 * @param verticalLayerDependency
-	 *            The layer to link the vertical dimension to, typically the column header layer
-	 * @param useDefaultConfiguration
-	 *            If default configuration should be applied to this layer (at moment none)
-	 * @param layerPainter
-	 *            The painter for this layer or <code>null</code> to use the painter of the base layer
-	 */
-	public CornerLayer(final ILayer baseLayer,
-			final ILayer horizontalLayerDependency, final ILayer verticalLayerDependency,
-			final boolean useDefaultConfiguration, final ILayerPainter layerPainter) {
-		super(baseLayer, horizontalLayerDependency, verticalLayerDependency);
-		
-		this.layerPainter= layerPainter;
-	}
-	
-	
-	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
-		final ILayerDim hDim= getDim(HORIZONTAL);
-		final ILayerDim vDim= getDim(VERTICAL);
-		final long columnId= hDim.getPositionId(columnPosition, columnPosition);
-		final long rowId= vDim.getPositionId(rowPosition, rowPosition);
-		
-		return new LayerCell(this,
-				new LayerCellDim(HORIZONTAL, columnId,
-						columnPosition, 0, hDim.getPositionCount() ),
-				new LayerCellDim(VERTICAL, rowId,
-						rowPosition, 0, getVerticalLayerDependency().getRowCount()) );
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/AbstractLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/AbstractLayer.java
deleted file mode 100644
index e8b3327a..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/AbstractLayer.java
+++ /dev/null
@@ -1,348 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.LinkedHashMap;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map;
-import java.util.Properties;
-
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.config.ConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.config.IConfiguration;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.coordinate.PixelOutOfBoundsException;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEventHandler;
-import org.eclipse.statet.ecommons.waltable.painter.layer.GridLineCellLayerPainter;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
-import org.eclipse.statet.ecommons.waltable.ui.IClientAreaProvider;
-import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
-import org.eclipse.statet.internal.ecommons.waltable.LayerListenerList;
-
-
-/**
- * Base layer implementation with common methods for managing listeners and caching, etc.
- */
-public abstract class AbstractLayer implements ILayer {
-	
-	
-	private ILayerDim hDim;
-	private ILayerDim vDim;
-	
-	protected ILayerPainter layerPainter;
-	private IClientAreaProvider clientAreaProvider= IClientAreaProvider.DEFAULT;
-	
-	private final Map<Class<? extends ILayerCommand>, ILayerCommandHandler<? extends ILayerCommand>> commandHandlers= new LinkedHashMap<>();
-	private final Map<Class<? extends ILayerEvent>, ILayerEventHandler<? extends ILayerEvent>> eventHandlers= new HashMap<>();
-	
-	private final List<IPersistable> persistables= new LinkedList<>();
-	private final LayerListenerList listeners= new LayerListenerList();
-	private final Collection<IConfiguration> configurations= new ArrayList<>();
-	
-	
-	protected AbstractLayer() {
-		initDims();
-		
-		this.layerPainter= createPainter();
-	}
-	
-	
-	// Dims
-	
-	/**
-	 * Updates the layer dimensions.
-	 * 
-	 * Override this method to set custom layer dimension implementations.
-	 */
-	protected abstract void initDims();
-	
-	
-	/**
-	 * Sets the layer dimension of this layer for the orientation of the given dimension.
-	 * 
-	 * This method use usually called in {@link #initDims()}.
-	 * 
-	 * @param dim the layer dimension
-	 */
-	protected void setDim(/*@NonNull*/ final ILayerDim dim) {
-		if (dim == null) {
-			throw new NullPointerException("dim"); //$NON-NLS-1$
-		}
-		
-		if (dim.getOrientation() == HORIZONTAL) {
-			this.hDim= dim;
-		}
-		else {
-			this.vDim= dim;
-		}
-	}
-	
-	@Override
-	public ILayerDim getDim(final Orientation orientation) {
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
-		}
-		
-		return (orientation == HORIZONTAL) ? this.hDim : this.vDim;
-	}
-	
-	
-	protected ILayerPainter createPainter() {
-		return null;
-	}
-	
-	
-	// Dispose
-	
-	@Override
-	public void dispose() {
-	}
-	
-	
-	// Regions
-	
-	@Override
-	public LabelStack getRegionLabelsByXY(final long x, final long y) {
-		return new LabelStack();
-	}
-	
-	// Persistence
-	
-	@Override
-	public void saveState(final String prefix, final Properties properties) {
-		for (final IPersistable persistable : this.persistables) {
-			persistable.saveState(prefix, properties);
-		}
-	}
-	
-	@Override
-	public void loadState(final String prefix, final Properties properties) {
-		for (final IPersistable persistable : this.persistables) {
-			persistable.loadState(prefix, properties);
-		}
-	}
-	  
-	@Override
-	public void registerPersistable(final IPersistable persistable){
-		this.persistables.add(persistable);
-	}
-
-	@Override
-	public void unregisterPersistable(final IPersistable persistable){
-		this.persistables.remove(persistable);
-	}
-	
-	// Configuration
-	
-	public void addConfiguration(final IConfiguration configuration) {
-		this.configurations.add(configuration);
-	}
-
-	public void clearConfiguration() {
-		this.configurations.clear();
-	}
-	
-	@Override
-	public void configure(final ConfigRegistry configRegistry, final UiBindingRegistry uiBindingRegistry) {
-		for (final IConfiguration configuration : this.configurations) {
-			configuration.configureLayer(this);
-			configuration.configureRegistry(configRegistry);
-			configuration.configureUiBindings(uiBindingRegistry);
-		}
-	}
-	
-	// Commands
-	
-	@Override
-	@SuppressWarnings("unchecked")
-	public boolean doCommand(final ILayerCommand command) {
-		for (final Class<? extends ILayerCommand> commandClass : this.commandHandlers.keySet()) {
-			if (commandClass.isInstance(command)) {
-				final ILayerCommandHandler commandHandler= this.commandHandlers.get(commandClass);
-				if (commandHandler.doCommand(this, command.cloneCommand())) {
-					return true;
-				}
-			}
-		}
-		
-		return false;
-	}
-	
-	// Command handlers
-	
-	/**
-	 * Layers should use this method to register their command handlers
-	 * and call it from their constructor. This allows easy overriding if 
-	 * required of command handlers 
-	 */
-	protected void registerCommandHandlers() {
-		// No op
-	}
-	
-	@Override
-	public void registerCommandHandler(final ILayerCommandHandler<?> commandHandler) {
-		this.commandHandlers.put(commandHandler.getCommandClass(), commandHandler);
-	}
-	
-	@Override
-	public void unregisterCommandHandler(final Class<? extends ILayerCommand> commandClass) {
-		this.commandHandlers.remove(commandClass);
-	}
-	
-	// Events
-	
-	@Override
-	public void addLayerListener(final ILayerListener listener) {
-		this.listeners.add(listener);
-	}
-	
-	@Override
-	public void removeLayerListener(final ILayerListener listener) {
-		this.listeners.remove(listener);
-	}
-	
-	/**
-	 * Handle layer event notification. Convert it to your context
-	 * and propagate <i>UP</i>.
-	 *  
-	 * If you override this method you <strong>MUST NOT FORGET</strong> to raise
-	 * the event up the layer stack by calling <code>super.fireLayerEvent(event)</code>
-	 * - unless you plan to eat the event yourself.
-	 **/
-	@Override
-	@SuppressWarnings("unchecked")
-	public void handleLayerEvent(final ILayerEvent event) {
-		for (final Class<? extends ILayerEvent> eventClass : this.eventHandlers.keySet()) {
-			if (eventClass.isInstance(event)) {
-				final ILayerEventHandler eventHandler= this.eventHandlers.get(eventClass);
-				eventHandler.handleLayerEvent(event);
-			}
-		}
-		
-		// Pass on the event to our parent
-		if (event.convertToLocal(this)) {
-			fireLayerEvent(event);
-		}
-	}
-	
-	public void registerEventHandler(final ILayerEventHandler<?> eventHandler) {
-		this.eventHandlers.put(eventHandler.getLayerEventClass(), eventHandler);
-	}
-	
-	public void unregisterEventHandler(final ILayerEventHandler<?> eventHandler) {
-		this.eventHandlers.remove(eventHandler.getLayerEventClass());
-	}
-	
-	/**
-	 * Pass the event to all the {@link ILayerListener} registered on this layer.
-	 * A cloned copy is passed to each listener.
-	 */
-	@Override
-	public void fireLayerEvent(final ILayerEvent event) {
-		final ILayerListener[] currentListeners= this.listeners.getListeners();
-		final int last= currentListeners.length - 1;
-		if (last >= 0) {
-			// Fire cloned event to first n-1 listeners; fire original event to last listener
-			for (int i= 0; i < last; i++) {
-				currentListeners[i].handleLayerEvent(event.cloneEvent());
-			}
-			currentListeners[last].handleLayerEvent(event);
-		}
-	}
-	
-	/**
-	 * @return {@link ILayerPainter}. Defaults to {@link GridLineCellLayerPainter}
-	 */
-	@Override
-	public ILayerPainter getLayerPainter() {
-		if (this.layerPainter == null) {
-			this.layerPainter= new GridLineCellLayerPainter();
-		}
-		return this.layerPainter;
-	}
-	
-	protected void setLayerPainter(final ILayerPainter layerPainter) {
-		this.layerPainter= layerPainter;
-	}
-
-	// Client area
-	
-	@Override
-	public IClientAreaProvider getClientAreaProvider() {
-		return this.clientAreaProvider;
-	}
-	
-	@Override
-	public void setClientAreaProvider(final IClientAreaProvider clientAreaProvider) {
-		this.clientAreaProvider= clientAreaProvider;
-	}
-	
-	
-	@Override
-	public final long getColumnCount() {
-		return this.hDim.getPositionCount();
-	}
-	
-	@Override
-	public final long getWidth() {
-		return this.hDim.getSize();
-	}
-	
-	@Override
-	public final long getColumnPositionByX(final long x) {
-		try {
-			return this.hDim.getPositionByPixel(x);
-		}
-		catch (final PixelOutOfBoundsException e) {
-			return Long.MIN_VALUE;
-		}
-	}
-	
-	
-	@Override
-	public final long getRowCount() {
-		return this.vDim.getPositionCount();
-	}
-	
-	@Override
-	public final long getHeight() {
-		return this.vDim.getSize();
-	}
-	
-	@Override
-	public final long getRowPositionByY(final long y) {
-		try {
-			return this.vDim.getPositionByPixel(y);
-		}
-		catch (final PixelOutOfBoundsException e) {
-			return Long.MIN_VALUE;
-		}
-	}
-	
-	
-	@Override
-	public String toString() {
-		return getClass().getSimpleName();
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ForwardLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ForwardLayer.java
deleted file mode 100644
index a4684e75..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/ForwardLayer.java
+++ /dev/null
@@ -1,162 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
-
-import java.util.Properties;
-
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.config.ConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ForwardLayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCellDim;
-import org.eclipse.statet.ecommons.waltable.layer.event.IStructuralChangeEvent;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-import org.eclipse.statet.ecommons.waltable.ui.IClientAreaProvider;
-import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
-
-
-public abstract class ForwardLayer extends AbstractLayer {
-	
-	
-	private final ILayer underlyingLayer;
-	
-	
-	public ForwardLayer(/*@NonNull*/ final ILayer underlyingLayer) {
-		if (underlyingLayer == null) {
-			throw new NullPointerException("underlyingLayer"); //$NON-NLS-1$
-		}
-		this.underlyingLayer= underlyingLayer;
-		this.underlyingLayer.setClientAreaProvider(getClientAreaProvider());
-		this.underlyingLayer.addLayerListener(this);
-		
-		initDims();
-	}
-	
-	
-	@Override
-	protected void initDims() {
-		final ILayer underlying= getUnderlyingLayer();
-		if (underlying == null) {
-			return;
-		}
-		setDim(new ForwardLayerDim<>(this, underlying.getDim(HORIZONTAL)));
-		setDim(new ForwardLayerDim<>(this, underlying.getDim(VERTICAL)));
-	}
-	
-	protected void setUnderlyingLayer(/*@NonNull*/ final ILayer underlyingLayer) {
-	}
-	
-	protected final ILayer getUnderlyingLayer() {
-		return this.underlyingLayer;
-	}
-	
-	// Dispose
-	
-	@Override
-	public void dispose() {
-		this.underlyingLayer.dispose();
-	}
-	
-	// Persistence
-	
-	@Override
-	public void saveState(final String prefix, final Properties properties) {
-		this.underlyingLayer.saveState(prefix, properties);
-		super.saveState(prefix, properties);
-	}
-	
-	/**
-	 * Underlying layers <i>must</i> load state first.
-	 * If this is not done, {@link IStructuralChangeEvent} from underlying
-	 * layers will reset caches after state has been loaded
-	 */
-	@Override
-	public void loadState(final String prefix, final Properties properties) {
-		this.underlyingLayer.loadState(prefix, properties);
-		super.loadState(prefix, properties);
-	}
-	
-	// Configuration
-	
-	@Override
-	public void configure(final ConfigRegistry configRegistry, final UiBindingRegistry uiBindingRegistry) {
-		this.underlyingLayer.configure(configRegistry, uiBindingRegistry);
-		super.configure(configRegistry, uiBindingRegistry);
-	}
-
-	@Override
-	public ILayerPainter getLayerPainter() {
-		return (this.layerPainter != null) ? this.layerPainter : this.underlyingLayer.getLayerPainter();
-	}
-	
-	// Command
-	
-	@Override
-	public boolean doCommand(final ILayerCommand command) {
-		if (super.doCommand(command)) {
-			return true;
-		}
-		
-		if (this.underlyingLayer != null) {
-			return this.underlyingLayer.doCommand(command);
-		}
-		
-		return false;
-	}
-	
-	// Client area
-	
-	@Override
-	public void setClientAreaProvider(final IClientAreaProvider clientAreaProvider) {
-		super.setClientAreaProvider(clientAreaProvider);
-		if (getUnderlyingLayer() != null) {
-			getUnderlyingLayer().setClientAreaProvider(clientAreaProvider);
-		}
-	}
-	
-	
-	// Cell features
-	
-	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
-		final ILayerCell underlyingCell= this.underlyingLayer.getCellByPosition(
-				columnPosition, rowPosition );
-		
-		return createCell(
-				underlyingCell.getDim(HORIZONTAL),
-				underlyingCell.getDim(VERTICAL),
-				underlyingCell );
-	}
-	
-	protected ILayerCell createCell(final ILayerCellDim hDim, final ILayerCellDim vDim,
-			final ILayerCell underlyingCell) {
-		return new ForwardLayerCell(this, hDim, vDim, underlyingCell);
-	}
-	
-	// IRegionResolver
-	
-	@Override
-	public LabelStack getRegionLabelsByXY(final long x, final long y) {
-		return this.underlyingLayer.getRegionLabelsByXY(x, y);
-	}
-	
-	@Override
-	public ILayer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
-		return this.underlyingLayer;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/AbstractOverrider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/AbstractOverrider.java
index a21875e5..12d434e4 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/AbstractOverrider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/AbstractOverrider.java
@@ -20,7 +20,7 @@ import java.util.List;
 import java.util.Map;
 
 
-public abstract class AbstractOverrider implements IConfigLabelAccumulator {
+public abstract class AbstractOverrider implements CellLabelContributor {
 	
 	
 	private final Map<Serializable, List<String>> overrides= new HashMap<>();
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/AggregrateConfigLabelAccumulator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/AggregrateConfigLabelAccumulator.java
index 66e68a4e..2c345250 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/AggregrateConfigLabelAccumulator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/AggregrateConfigLabelAccumulator.java
@@ -17,18 +17,18 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
 
 
 /**
- * An {@link IConfigLabelAccumulator} that can aggregate labels from other <code>IConfigLabelAccumulator</code>s. 
+ * An {@link CellLabelContributor} that can aggregate labels from other <code>IConfigLabelAccumulator</code>s. 
  * All the labels provided by the aggregated accumulators are applied to the cell.
  */
-public class AggregrateConfigLabelAccumulator implements IConfigLabelAccumulator {
+public class AggregrateConfigLabelAccumulator implements CellLabelContributor {
     
-    private final List<IConfigLabelAccumulator> accumulators= new ArrayList<>();
+    private final List<CellLabelContributor> accumulators= new ArrayList<>();
     
-    public void add(final IConfigLabelAccumulator r) {
+    public void add(final CellLabelContributor r) {
         if (r == null)
 		 {
 			throw new IllegalArgumentException("null"); //$NON-NLS-1$
@@ -36,7 +36,7 @@ public class AggregrateConfigLabelAccumulator implements IConfigLabelAccumulator
         this.accumulators.add(r);
     }
 
-    public void add(final IConfigLabelAccumulator... r) {
+    public void add(final CellLabelContributor... r) {
     	if (r == null)
 		 {
 			throw new IllegalArgumentException("null"); //$NON-NLS-1$
@@ -45,9 +45,9 @@ public class AggregrateConfigLabelAccumulator implements IConfigLabelAccumulator
     }
 
     @Override
-	public void accumulateConfigLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
-        for (final IConfigLabelAccumulator accumulator : this.accumulators) {
-        	accumulator.accumulateConfigLabels(configLabels, columnPosition, rowPosition);
+	public void addLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
+        for (final CellLabelContributor accumulator : this.accumulators) {
+        	accumulator.addLabels(configLabels, columnPosition, rowPosition);
         }
     }
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/BodyOverrideConfigLabelAccumulator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/BodyOverrideConfigLabelAccumulator.java
deleted file mode 100644
index edf7320b..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/BodyOverrideConfigLabelAccumulator.java
+++ /dev/null
@@ -1,43 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.cell;
-
-import java.util.Arrays;
-import java.util.List;
-
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-
-
-/**
- * Applies the given labels to all the cells in the grid.
- * Used to apply styles to the entire grid.
- */
-public class BodyOverrideConfigLabelAccumulator implements IConfigLabelAccumulator {
-
-	private List<String> configLabels;
-
-	@Override
-	public void accumulateConfigLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
-		configLabels.getLabels().addAll(this.configLabels);
-	}
-
-	public void registerOverrides(final String... configLabels) {
-		this.configLabels= Arrays.asList(configLabels);
-	}
-
-	public void addOverride(final String configLabel) {
-		this.configLabels.add(configLabel);
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellDisplayConversionUtils.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellDisplayConversionUtils.java
index 605ebfa4..35a28026 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellDisplayConversionUtils.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellDisplayConversionUtils.java
@@ -14,24 +14,25 @@
 package org.eclipse.statet.ecommons.waltable.layer.cell;
 
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
 
 
 public final class CellDisplayConversionUtils {
 	
 	
-	public static String convertDataType(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	public static String convertDataType(final LayerCell cell, final ConfigRegistry configRegistry) {
 		return convertDataType(cell, cell.getDataValue(0, null), configRegistry);
 	}
 	
-	public static String convertDataType(final ILayerCell cell, final Object canonicalValue, final IConfigRegistry configRegistry) {
+	public static String convertDataType(final LayerCell cell, final Object canonicalValue, final ConfigRegistry configRegistry) {
 		Object displayValue;
 		
-		final IDisplayConverter displayConverter= configRegistry.getConfigAttribute(
+		final IDisplayConverter displayConverter= configRegistry.getAttribute(
 				CellConfigAttributes.DISPLAY_CONVERTER,
 				cell.getDisplayMode(),
-				cell.getConfigLabels().getLabels());
+				cell.getLabels().getLabels());
 		
 		if (displayConverter != null) {
 			displayValue= displayConverter.canonicalToDisplayValue(cell, configRegistry, canonicalValue);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/IConfigLabelAccumulator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellLabelContributor.java
index 1bd539bf..c841d6ee 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/IConfigLabelAccumulator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellLabelContributor.java
@@ -13,16 +13,20 @@
 
 package org.eclipse.statet.ecommons.waltable.layer.cell;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
 
 
 /**
  * Resolves the configuration/config label(s) which are tied to a given cell.
- * Various attributes can be registered in the {@link IConfigRegistry} against this
+ * Various attributes can be registered in the {@link ConfigRegistry} against this
  * label
  */
-public interface IConfigLabelAccumulator {
+@NonNullByDefault
+public interface CellLabelContributor {
+	
 	
 	/**
 	 * Add labels applicable to this cell position
@@ -31,6 +35,6 @@ public interface IConfigLabelAccumulator {
 	 * @param columnPosition of the cell for which labels are being gathered
 	 * @param rowPosition of the cell for which labels are being gathered
 	 */
-	public void accumulateConfigLabels(LabelStack configLabels, long columnPosition, long rowPosition);
+	void addLabels(LabelStack configLabels, long columnPosition, long rowPosition);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellOverrideLabelAccumulator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellOverrideLabelAccumulator.java
index 7c8527cf..51a421b0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellOverrideLabelAccumulator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/CellOverrideLabelAccumulator.java
@@ -16,8 +16,8 @@ package org.eclipse.statet.ecommons.waltable.layer.cell;
 import java.io.Serializable;
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
 
 
 /**
@@ -30,16 +30,16 @@ import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
 public class CellOverrideLabelAccumulator<T> extends AbstractOverrider {
 	
 	
-	private final IDataProvider dataProvider;
+	private final DataProvider dataProvider;
 	
 	
-	public CellOverrideLabelAccumulator(final IDataProvider dataProvider) {
+	public CellOverrideLabelAccumulator(final DataProvider dataProvider) {
 		this.dataProvider= dataProvider;
 	}
 	
 	
 	@Override
-	public void accumulateConfigLabels(final LabelStack configLabels, final long columnIndex, final long rowIndex) {
+	public void addLabels(final LabelStack configLabels, final long columnIndex, final long rowIndex) {
 		final List<String> cellLabels= getConfigLabels(
 				this.dataProvider.getDataValue(columnIndex, rowIndex, 0, null), columnIndex);
 		if (cellLabels == null) {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ClassNameConfigLabelAccumulator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ClassNameConfigLabelAccumulator.java
index 45f43346..4328fdfe 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ClassNameConfigLabelAccumulator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ClassNameConfigLabelAccumulator.java
@@ -13,25 +13,25 @@
 
 package org.eclipse.statet.ecommons.waltable.layer.cell;
 
-import org.eclipse.statet.ecommons.waltable.data.IRowDataProvider;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
 
 
 /**
  * Adds the Java class name of the cell's data value as a label.   
  */
-public class ClassNameConfigLabelAccumulator implements IConfigLabelAccumulator {
+public class ClassNameConfigLabelAccumulator implements CellLabelContributor {
 	
 	
-	private final IRowDataProvider<?> dataProvider;
+	private final DataProvider dataProvider;
 	
 	
-	public ClassNameConfigLabelAccumulator(final IRowDataProvider<?> dataProvider) {
+	public ClassNameConfigLabelAccumulator(final DataProvider dataProvider) {
 		this.dataProvider= dataProvider;
 	}
 	
 	@Override
-	public void accumulateConfigLabels(final LabelStack configLabel, final long columnPosition, final long rowPosition) {
+	public void addLabels(final LabelStack configLabel, final long columnPosition, final long rowPosition) {
 		final Object value= this.dataProvider.getDataValue(columnPosition, rowPosition, 0, null);
 		if (value != null) {
 			configLabel.addLabel(value.getClass().getName());
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ColumnLabelAccumulator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ColumnLabelAccumulator.java
deleted file mode 100644
index ea9e0968..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ColumnLabelAccumulator.java
+++ /dev/null
@@ -1,37 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.cell;
-
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-
-
-/**
- * Accumulator for column labels allowing to configure cells by their column position.
- * 
- * The label of a column is {@link #COLUMN_LABEL_PREFIX} + column position.
- */
-public class ColumnLabelAccumulator implements IConfigLabelAccumulator {
-
-	/**
-	 * The common prefix of column labels (value is {@value}).
-	 */
-	public static final String COLUMN_LABEL_PREFIX= "COLUMN_"; //$NON-NLS-1$
-
-
-	@Override
-	public void accumulateConfigLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
-		configLabels.addLabel(COLUMN_LABEL_PREFIX + columnPosition);
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ColumnOverrideLabelAccumulator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ColumnOverrideLabelAccumulator.java
index 63cfd696..98e1878a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ColumnOverrideLabelAccumulator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/ColumnOverrideLabelAccumulator.java
@@ -13,46 +13,44 @@
 
 package org.eclipse.statet.ecommons.waltable.layer.cell;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import java.io.Serializable;
 import java.util.List;
 import java.util.Map;
-import java.util.Properties;
-import java.util.Set;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
 
 
 /**
  * Registers/Adds configuration labels for a given column (by index).
- * Custom {@link ICellEditor}, {@link ICellPainter}, {@link IStyle} can then 
- * be registered in the {@link IConfigRegistry} against these labels.
+ * Custom {@link ICellEditor}, {@link LayerCellPainter}, {@link Style} can then 
+ * be registered in the {@link ConfigRegistry} against these labels.
  * 
  * Also @see {@link RowOverrideLabelAccumulator} 
  */
-public class ColumnOverrideLabelAccumulator extends AbstractOverrider implements IPersistable {
+public class ColumnOverrideLabelAccumulator extends AbstractOverrider implements Persistable {
 	
 	
 	public static final String PERSISTENCE_KEY= ".columnOverrideLabelAccumulator"; //$NON-NLS-1$
 	
 	
-	private final ILayer layer;
+	private final Layer layer;
 	
 	
-	public ColumnOverrideLabelAccumulator(final ILayer layer) {
+	public ColumnOverrideLabelAccumulator(final Layer layer) {
 		this.layer= layer;
 	}
 	
 	
 	@Override
-	public void accumulateConfigLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
+	public void addLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
 		final long columnIndex= this.layer.getDim(HORIZONTAL)
 				.getPositionId(columnPosition, columnPosition);
 		final List<String> overrides= getOverrides(Long.valueOf(columnIndex));
@@ -86,7 +84,7 @@ public class ColumnOverrideLabelAccumulator extends AbstractOverrider implements
 	 * prefix.columnOverrideLabelAccumulator.0= LABEL1,LABEL2
 	 */
 	@Override
-	public void saveState(final String prefix, final Properties properties) {
+	public void saveState(final String prefix, final Map<String, String> properties) {
 		final Map<Serializable, List<String>> overrides= getOverrides();
 
 		for (final Map.Entry<Serializable, List<String>> entry : overrides.entrySet()) {
@@ -101,22 +99,21 @@ public class ColumnOverrideLabelAccumulator extends AbstractOverrider implements
 				propertyValue= propertyValue.substring(0, propertyValue.length() - 1);
 			}
 			final String propertyKey= prefix + PERSISTENCE_KEY + DOT + entry.getKey();
-			properties.setProperty(propertyKey, propertyValue);
+			properties.put(propertyKey, propertyValue);
 		}
 	}
 
 	/**
 	 * Load the overrides state from the given properties file.
-	 * @see #saveState(String, Properties)
+	 * @see #saveState(String, Map)
 	 */
 	@Override
-	public void loadState(final String prefix, final Properties properties) {
-		final Set<Object> keySet= properties.keySet();
-		for (final Object key : keySet) {
-			final String keyString= (String) key;
-			if(keyString.contains(PERSISTENCE_KEY)){
-				final String labelsFromPropertyValue= properties.getProperty(keyString).trim();
-				final String columnIndexFromKey= keyString.substring(keyString.lastIndexOf(DOT) + 1);
+	public void loadState(final String prefix, final Map<String, String> properties) {
+		for (final var entry : properties.entrySet()) {
+			final var key= entry.getKey();
+			if (key.contains(PERSISTENCE_KEY)){
+				final String labelsFromPropertyValue= entry.getValue().trim();
+				final String columnIndexFromKey= key.substring(key.lastIndexOf(DOT) + 1);
 				registerColumnOverrides(Long.parseLong(columnIndexFromKey), labelsFromPropertyValue.split(VALUE_SEPARATOR));
 			}
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/SimpleConfigLabelAccumulator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/SimpleLabelContributor.java
index cafe3100..3619d170 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/SimpleConfigLabelAccumulator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/cell/SimpleLabelContributor.java
@@ -13,19 +13,25 @@
 
 package org.eclipse.statet.ecommons.waltable.layer.cell;
 
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
 
-public class SimpleConfigLabelAccumulator implements IConfigLabelAccumulator {
 
+@NonNullByDefault
+public class SimpleLabelContributor implements CellLabelContributor {
+	
+	
 	private final String configLabel;
-
-	public SimpleConfigLabelAccumulator(final String configLabel) {
+	
+	
+	public SimpleLabelContributor(final String configLabel) {
 		this.configLabel= configLabel;
 	}
-
+	
+	
 	@Override
-	public void accumulateConfigLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
+	public void addLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
 		configLabels.addLabel(this.configLabel);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultColumnHeaderLayerConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultColumnHeaderLayerConfiguration.java
index 3728658e..93b8b404 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultColumnHeaderLayerConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultColumnHeaderLayerConfiguration.java
@@ -14,8 +14,8 @@
 package org.eclipse.statet.ecommons.waltable.layer.config;
 
 import org.eclipse.statet.ecommons.waltable.config.AggregateConfiguration;
-import org.eclipse.statet.ecommons.waltable.grid.layer.ColumnHeaderLayer;
-import org.eclipse.statet.ecommons.waltable.resize.config.DefaultColumnResizeBindings;
+import org.eclipse.statet.ecommons.waltable.grid.core.layers.ColumnHeaderLayer;
+import org.eclipse.statet.ecommons.waltable.resize.ui.action.DefaultColumnResizeBindings;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultColumnHeaderStyleConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultColumnHeaderStyleConfiguration.java
index 808ec795..02907edd 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultColumnHeaderStyleConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultColumnHeaderStyleConfiguration.java
@@ -20,17 +20,17 @@ import org.eclipse.swt.graphics.FontData;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractRegistryConfiguration;
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.VerticalAlignment;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 import org.eclipse.statet.ecommons.waltable.painter.cell.TextPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.decorator.BeveledBorderDecorator;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
-import org.eclipse.statet.ecommons.waltable.style.Style;
-import org.eclipse.statet.ecommons.waltable.style.VerticalAlignment;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -44,30 +44,30 @@ public class DefaultColumnHeaderStyleConfiguration extends AbstractRegistryConfi
 	public Color bgColor= GUIHelper.COLOR_WIDGET_BACKGROUND;
 	public Color fgColor= GUIHelper.COLOR_WIDGET_FOREGROUND;
 	public Color gradientBgColor= GUIHelper.COLOR_WHITE;
-	public Color gradientFgColor= GUIHelper.getColor(136, 212, 215);
+	public Color gradientFgColor= new Color(136, 212, 215);
 	public HorizontalAlignment hAlign= HorizontalAlignment.CENTER;
 	public VerticalAlignment vAlign= VerticalAlignment.MIDDLE;
 	public BorderStyle borderStyle= null;
 
-	public ICellPainter cellPainter= new BeveledBorderDecorator(new TextPainter());
+	public LayerCellPainter layerCellPainter= new BeveledBorderDecorator(new TextPainter());
 
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_PAINTER, this.cellPainter, DisplayMode.NORMAL, GridRegion.COLUMN_HEADER);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_PAINTER, this.cellPainter, DisplayMode.NORMAL, GridRegion.CORNER);
+	public void configureRegistry(final ConfigRegistry configRegistry) {
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_PAINTER, this.layerCellPainter, DisplayMode.NORMAL, GridLabels.COLUMN_HEADER);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_PAINTER, this.layerCellPainter, DisplayMode.NORMAL, GridLabels.CORNER);
 
 		// Normal
-		final Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR, this.bgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.FOREGROUND_COLOR, this.fgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.GRADIENT_BACKGROUND_COLOR, this.gradientBgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.GRADIENT_FOREGROUND_COLOR, this.gradientFgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.HORIZONTAL_ALIGNMENT, this.hAlign);
-		cellStyle.setAttributeValue(CellStyleAttributes.VERTICAL_ALIGNMENT, this.vAlign);
-		cellStyle.setAttributeValue(CellStyleAttributes.BORDER_STYLE, this.borderStyle);
-		cellStyle.setAttributeValue(CellStyleAttributes.FONT, this.font);
+		final BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR, this.bgColor);
+		cellStyle.setAttributeValue(CellStyling.FOREGROUND_COLOR, this.fgColor);
+		cellStyle.setAttributeValue(CellStyling.GRADIENT_BACKGROUND_COLOR, this.gradientBgColor);
+		cellStyle.setAttributeValue(CellStyling.GRADIENT_FOREGROUND_COLOR, this.gradientFgColor);
+		cellStyle.setAttributeValue(CellStyling.HORIZONTAL_ALIGNMENT, this.hAlign);
+		cellStyle.setAttributeValue(CellStyling.VERTICAL_ALIGNMENT, this.vAlign);
+		cellStyle.setAttributeValue(CellStyling.BORDER_STYLE, this.borderStyle);
+		cellStyle.setAttributeValue(CellStyling.FONT, this.font);
 
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, GridRegion.COLUMN_HEADER);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, GridRegion.CORNER);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, GridLabels.COLUMN_HEADER);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, GridLabels.CORNER);
 	}
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultRowHeaderLayerConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultRowHeaderLayerConfiguration.java
index 812c9327..5504ca87 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultRowHeaderLayerConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultRowHeaderLayerConfiguration.java
@@ -14,16 +14,16 @@
 package org.eclipse.statet.ecommons.waltable.layer.config;
 
 import org.eclipse.statet.ecommons.waltable.config.AggregateConfiguration;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.grid.layer.RowHeaderLayer;
-import org.eclipse.statet.ecommons.waltable.resize.config.DefaultRowResizeBindings;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
+import org.eclipse.statet.ecommons.waltable.grid.core.layers.RowHeaderLayer;
+import org.eclipse.statet.ecommons.waltable.resize.ui.action.DefaultRowResizeBindings;
 
 
 /**
  * Default setup for the Row header area. Added by the {@link RowHeaderLayer}
  * Override the methods in this class to customize style / UI bindings.
  * 
- * @see GridRegion
+ * @see GridLabels
  */
 public class DefaultRowHeaderLayerConfiguration extends AggregateConfiguration {
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultRowHeaderStyleConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultRowHeaderStyleConfiguration.java
index ef03bc0a..3b55b20f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultRowHeaderStyleConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/config/DefaultRowHeaderStyleConfiguration.java
@@ -20,16 +20,16 @@ import org.eclipse.swt.graphics.FontData;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractRegistryConfiguration;
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.VerticalAlignment;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 import org.eclipse.statet.ecommons.waltable.painter.cell.TextPainter;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
-import org.eclipse.statet.ecommons.waltable.style.Style;
-import org.eclipse.statet.ecommons.waltable.style.VerticalAlignment;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -39,35 +39,35 @@ public class DefaultRowHeaderStyleConfiguration extends AbstractRegistryConfigur
 	public Color bgColor= GUIHelper.COLOR_WIDGET_BACKGROUND;
 	public Color fgColor= GUIHelper.COLOR_WIDGET_FOREGROUND;
 	public Color gradientBgColor= GUIHelper.COLOR_WHITE;
-	public Color gradientFgColor= GUIHelper.getColor(136, 212, 215);
+	public Color gradientFgColor= new Color(136, 212, 215);
 	public HorizontalAlignment hAlign= HorizontalAlignment.CENTER;
 	public VerticalAlignment vAlign= VerticalAlignment.MIDDLE;
 	public BorderStyle borderStyle= null;
 
-	public ICellPainter cellPainter= new TextPainter();
+	public LayerCellPainter layerCellPainter= new TextPainter();
 
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
+	public void configureRegistry(final ConfigRegistry configRegistry) {
 		configureRowHeaderCellPainter(configRegistry);
 		configureRowHeaderStyle(configRegistry);
 	}
 
-	protected void configureRowHeaderStyle(final IConfigRegistry configRegistry) {
-		final Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR, this.bgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.FOREGROUND_COLOR, this.fgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.GRADIENT_BACKGROUND_COLOR, this.gradientBgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.GRADIENT_FOREGROUND_COLOR, this.gradientFgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.HORIZONTAL_ALIGNMENT, this.hAlign);
-		cellStyle.setAttributeValue(CellStyleAttributes.VERTICAL_ALIGNMENT, this.vAlign);
-		cellStyle.setAttributeValue(CellStyleAttributes.BORDER_STYLE, this.borderStyle);
-		cellStyle.setAttributeValue(CellStyleAttributes.FONT, this.font);
+	protected void configureRowHeaderStyle(final ConfigRegistry configRegistry) {
+		final BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR, this.bgColor);
+		cellStyle.setAttributeValue(CellStyling.FOREGROUND_COLOR, this.fgColor);
+		cellStyle.setAttributeValue(CellStyling.GRADIENT_BACKGROUND_COLOR, this.gradientBgColor);
+		cellStyle.setAttributeValue(CellStyling.GRADIENT_FOREGROUND_COLOR, this.gradientFgColor);
+		cellStyle.setAttributeValue(CellStyling.HORIZONTAL_ALIGNMENT, this.hAlign);
+		cellStyle.setAttributeValue(CellStyling.VERTICAL_ALIGNMENT, this.vAlign);
+		cellStyle.setAttributeValue(CellStyling.BORDER_STYLE, this.borderStyle);
+		cellStyle.setAttributeValue(CellStyling.FONT, this.font);
 
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, GridRegion.ROW_HEADER);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, GridLabels.ROW_HEADER);
 	}
 
-	protected void configureRowHeaderCellPainter(final IConfigRegistry configRegistry) {
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_PAINTER, this.cellPainter, DisplayMode.NORMAL, GridRegion.ROW_HEADER);
+	protected void configureRowHeaderCellPainter(final ConfigRegistry configRegistry) {
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_PAINTER, this.layerCellPainter, DisplayMode.NORMAL, GridLabels.ROW_HEADER);
 	}
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/AbstractContextFreeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/AbstractContextFreeEvent.java
deleted file mode 100644
index 530c4c7d..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/AbstractContextFreeEvent.java
+++ /dev/null
@@ -1,26 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-public abstract class AbstractContextFreeEvent implements ILayerEvent {
-
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		return true;
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/CellVisualChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/CellVisualChangeEvent.java
deleted file mode 100644
index 84b3bce0..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/CellVisualChangeEvent.java
+++ /dev/null
@@ -1,82 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
-
-import java.util.Arrays;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-public class CellVisualChangeEvent implements IVisualChangeEvent {
-
-	protected ILayer layer;
-	
-	protected long columnPosition;
-	
-	protected long rowPosition;
-	
-	public CellVisualChangeEvent(final ILayer layer, final long columnPosition, final long rowPosition) {
-		this.layer= layer;
-		this.columnPosition= columnPosition;
-		this.rowPosition= rowPosition;
-	}
-	
-	protected CellVisualChangeEvent(final CellVisualChangeEvent event) {
-		this.layer= event.layer;
-		this.columnPosition= event.columnPosition;
-		this.rowPosition= event.rowPosition;
-	}
-	
-	@Override
-	public ILayer getLayer() {
-		return this.layer;
-	}
-	
-	public long getColumnPosition() {
-		return this.columnPosition;
-	}
-	
-	public long getRowPosition() {
-		return this.rowPosition;
-	}
-	
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		this.columnPosition= localLayer.getDim(HORIZONTAL).underlyingToLocalPosition(
-				this.layer.getDim(HORIZONTAL), this.columnPosition );
-		this.rowPosition= localLayer.getDim(VERTICAL).underlyingToLocalPosition(
-				this.layer.getDim(VERTICAL), this.rowPosition );
-		
-		this.layer= localLayer;
-		
-		return this.columnPosition >= 0 && this.rowPosition >= 0
-			&& this.columnPosition < this.layer.getColumnCount() && this.rowPosition < this.layer.getRowCount();
-	}
-	
-	@Override
-	public Collection<LRectangle> getChangedPositionRectangles() {
-		return Arrays.asList(new LRectangle[] { new LRectangle(this.columnPosition, this.rowPosition, 1, 1) });
-	}
-	
-	@Override
-	public CellVisualChangeEvent cloneEvent() {
-		return new CellVisualChangeEvent(this);
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/CellVisualUpdateEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/CellVisualUpdateEvent.java
deleted file mode 100644
index 49394fd4..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/CellVisualUpdateEvent.java
+++ /dev/null
@@ -1,68 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2013, 2021 Dirk Fauth and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Dirk Fauth <dirk.fauth@gmail.com> - initial API and implementation
- #=============================================================================*/ 
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-/**
- * Specialization of the CellVisualChangeEvent. The only difference is the handling
- * of this type of event in the NatTable event handling. While the CellVisualChangeEvent
- * causes a whole redraw operation of the visible part (which is necessary to update everything
- * if a data value has change, for example important for conditional styling), this event 
- * only forces to redraw the specified cell itself. This is for example necessary for hover styling,
- * where redrawing everything is not necessary and would cause lags in applying hover styling.
- */
-public class CellVisualUpdateEvent extends CellVisualChangeEvent {
-
-	/**
-	 * Create a new CellVisualUpdateEvent based on the given information.
-	 * 
-	 * @param layer The layer to which the given column and row position belong.
-	 * @param columnPosition The column position of the cell that needs to be redrawn.
-	 * @param rowPosition The row position of the cell that needs to be redrawn.
-	 */
-	public CellVisualUpdateEvent(final ILayer layer, final int columnPosition, final int rowPosition) {
-		super(layer, columnPosition, rowPosition);
-	}
-
-	/**
-	 * Create a new CellVisualUpdateEvent out of the given event.
-	 * Used internally for cloning purposes.
-	 * 
-	 * @param event The event to create the clone from.
-	 */
-	protected CellVisualUpdateEvent(final CellVisualChangeEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public CellVisualUpdateEvent cloneEvent() {
-		return new CellVisualUpdateEvent(this);
-	}
-	
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-//		if (!(localLayer instanceof DimensionallyDependentLayer)) {
-//			columnPosition= localLayer.underlyingToLocalColumnPosition(getLayer(), columnPosition);
-//			rowPosition= localLayer.underlyingToLocalRowPosition(getLayer(), rowPosition);
-//		}
-		
-		this.layer= localLayer;
-		
-		return this.columnPosition >= 0 && this.rowPosition >= 0
-			&& this.columnPosition < this.layer.getColumnCount() && this.rowPosition < this.layer.getRowCount();
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ColumnStructuralChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ColumnStructuralChangeEvent.java
deleted file mode 100644
index 4c52726c..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ColumnStructuralChangeEvent.java
+++ /dev/null
@@ -1,94 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-/**
- * Event indicating a change in the structure of the columns. 
- * This event carried ColumnDiffs (Collection&lt;StructuralDiff&gt;) indicating the columns which have changed. 
- */
-public abstract class ColumnStructuralChangeEvent extends ColumnVisualChangeEvent implements IStructuralChangeEvent {
-
-	/**
-	 * Creates a new ColumnStructuralChangeEvent based on the given information.
-	 * @param layer The ILayer to which the given column positions match.
-	 * @param columnPositionRanges The column position ranges for the columns that have changed.
-	 */
-	public ColumnStructuralChangeEvent(final ILayer layer, final LRange...columnPositionRanges) {
-		this(layer, Arrays.asList(columnPositionRanges));
-	}
-	
-	/**
-	 * Creates a new ColumnStructuralChangeEvent based on the given information.
-	 * @param layer The ILayer to which the given column positions match.
-	 * @param columnPositionRanges The column position ranges for the columns that have changed.
-	 */
-	public ColumnStructuralChangeEvent(final ILayer layer, final Collection<LRange> columnPositionRanges) {
-		super(layer, columnPositionRanges);
-	}
-	
-	/**
-	 * Creates a new ColumnStructuralChangeEvent based on the given instance.
-	 * Mainly needed for cloning.
-	 * @param event The ColumnStructuralChangeEvent out of which the new instance should be created.
-	 */
-	protected ColumnStructuralChangeEvent(final ColumnStructuralChangeEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public Collection<LRectangle> getChangedPositionRectangles() {
-		final Collection<LRectangle> changedPositionRectangles= new ArrayList<>();
-		
-		final Collection<LRange> columnPositionRanges= getColumnPositionRanges();
-		if (columnPositionRanges != null && columnPositionRanges.size() > 0) {
-			long leftmostColumnPosition= Long.MAX_VALUE;
-			for (final LRange lRange : columnPositionRanges) {
-				if (lRange.start < leftmostColumnPosition) {
-					leftmostColumnPosition= lRange.start;
-				}
-			}
-			
-			final long columnCount= getLayer().getColumnCount();
-			final long rowCount= getLayer().getRowCount();
-			changedPositionRectangles.add(new LRectangle(leftmostColumnPosition, 0, columnCount - leftmostColumnPosition, rowCount));
-		}
-		
-		return changedPositionRectangles;
-	}
-	
-	@Override
-	public boolean isHorizontalStructureChanged() {
-		return true;
-	}
-	
-	@Override
-	public boolean isVerticalStructureChanged() {
-		return false;
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getRowDiffs() {
-		return null;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ColumnStructuralRefreshEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ColumnStructuralRefreshEvent.java
deleted file mode 100644
index b9ed0ff4..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ColumnStructuralRefreshEvent.java
+++ /dev/null
@@ -1,40 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-/**
- * General event indicating that columns cached by the layers need refreshing. 
- * 
- * Note: As opposed to the the {@link ColumnStructuralChangeEvent} this event does not 
- * indicate the specific columns which have changed.
- */
-public class ColumnStructuralRefreshEvent extends StructuralRefreshEvent {
-
-	public ColumnStructuralRefreshEvent(final ILayer layer) {
-		super(layer);
-	}
-	
-	@Override
-	public boolean isHorizontalStructureChanged() {
-		return true;
-	}
-	
-	@Override
-	public boolean isVerticalStructureChanged() {
-		return false;
-	}
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ColumnVisualChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ColumnVisualChangeEvent.java
deleted file mode 100644
index bb1e89f7..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ColumnVisualChangeEvent.java
+++ /dev/null
@@ -1,119 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-/**
- * An event that indicates a visible change to one ore more columns in the layer.
- */
-public abstract class ColumnVisualChangeEvent implements IVisualChangeEvent {
-
-	/**
-	 * The ILayer to which the given column positions match
-	 */
-	private ILayer layer;
-	/**
-	 * The column position ranges for the columns that have changed.
-	 * They are related to the set ILayer.
-	 */
-	private Collection<LRange> columnPositionRanges;
-	
-	/**
-	 * Creates a new ColumnVisualChangeEvent based on the given information.
-	 * @param layer The ILayer to which the given column positions match.
-	 * @param columnPositionRanges The column position ranges for the columns that have changed.
-	 */
-	public ColumnVisualChangeEvent(final ILayer layer, final LRange...columnPositionRanges) {
-		this(layer, Arrays.asList(columnPositionRanges));
-	}
-	
-	/**
-	 * Creates a new ColumnVisualChangeEvent based on the given information.
-	 * @param layer The ILayer to which the given column positions match.
-	 * @param columnPositionRanges The column position ranges for the columns that have changed.
-	 */
-	public ColumnVisualChangeEvent(final ILayer layer, final Collection<LRange> columnPositionRanges) {
-		this.layer= layer;
-		this.columnPositionRanges= columnPositionRanges;
-	}
-	
-	/**
-	 * Creates a new ColumnVisualChangeEvent based on the given instance.
-	 * Mainly needed for cloning.
-	 * @param event The ColumnVisualChangeEvent out of which the new instance should be created.
-	 */
-	protected ColumnVisualChangeEvent(final ColumnVisualChangeEvent event) {
-		this.layer= event.layer;
-		this.columnPositionRanges= event.columnPositionRanges;
-	}
-	
-	@Override
-	public ILayer getLayer() {
-		return this.layer;
-	}
-	
-	/**
-	 * @return The column position ranges for the columns that have changed.
-	 */
-	public Collection<LRange> getColumnPositionRanges() {
-		return this.columnPositionRanges;
-	}
-	
-	/**
-	 * Sets the column position ranges for the columns that have changed. 
-	 * Only for internal use in cases where the constructor needs to calculate the column
-	 * position ranges within the child constructor.
-	 * @param columnPositionRanges The column position ranges for the columns that have changed.
-	 */
-	protected void setColumnPositionRanges(final Collection<LRange> columnPositionRanges) {
-		this.columnPositionRanges= columnPositionRanges;
-	}
-	
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		this.columnPositionRanges= localLayer.getDim(HORIZONTAL).underlyingToLocalPositions(
-				this.layer.getDim(HORIZONTAL), this.columnPositionRanges );
-		this.layer= localLayer;
-		
-		return this.columnPositionRanges != null && this.columnPositionRanges.size() > 0;
-	}
-	
-	@Override
-	public Collection<LRectangle> getChangedPositionRectangles() {
-		final Collection<LRectangle> changedPositionRectangles= new ArrayList<>();
-		
-		final long rowCount= this.layer.getRowCount();
-		for (final LRange lRange : this.columnPositionRanges) {
-			changedPositionRectangles.add(new LRectangle(lRange.start, 0, lRange.end - lRange.start, rowCount));
-		}
-		
-		return changedPositionRectangles;
-	}
-	
-	@Override
-	public String toString() {
-		return getClass().getSimpleName();
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ILayerEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ILayerEvent.java
deleted file mode 100644
index c0bddd77..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ILayerEvent.java
+++ /dev/null
@@ -1,42 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-/**
- * Event fired by the {@link ILayerCommandHandler} classes (usually to signal to handling of a {@link ILayerCommand}).
- * Every layer in the grid is given a chance to respond to an event via {@link ILayer#handleLayerEvent(ILayerEvent)}.
- * 
- *  @see ILayerEventHandler
- */
-public interface ILayerEvent {
-
-	/**
-	 * Convert the column/row positions carried by the event to the layer about to
-	 * handle the event.
-	 * @param localLayer layer about to receive the event
-	 * @return TRUE if successfully converted, FALSE otherwise
-	 */
-	public boolean convertToLocal(ILayer localLayer);
-
-	/**
-	 * @return A cloned copy of the event. This cloned copy is provided to each listener.
-	 */
-	public ILayerEvent cloneEvent();
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ILayerEventHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ILayerEventHandler.java
deleted file mode 100644
index 18b5fd5f..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ILayerEventHandler.java
+++ /dev/null
@@ -1,23 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-
-public interface ILayerEventHandler <T extends ILayerEvent> {
-
-	public void handleLayerEvent(T event);
-	
-	public Class<T> getLayerEventClass();
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/PropertyUpdateEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/PropertyUpdateEvent.java
deleted file mode 100644
index b31475dc..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/PropertyUpdateEvent.java
+++ /dev/null
@@ -1,86 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import java.beans.PropertyChangeEvent;
-import java.util.Arrays;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-public class PropertyUpdateEvent<T> implements IVisualChangeEvent {
-
-	private final PropertyChangeEvent propertyChangeEvent= null;
-	private final T sourceBean;
-	private final String propertyName;
-	private final Object newValue;
-	private final Object oldValue;
-
-	private ILayer layer;
-
-	public PropertyUpdateEvent(final ILayer layer, final T sourceBean, final String propertyName, final Object oldValue, final Object newValue) {
-		this.layer= layer;
-		this.sourceBean= sourceBean;
-		this.propertyName= propertyName;
-		this.oldValue= oldValue;
-		this.newValue= newValue;
-	}
-
-	// Interface methods
-
-	@Override
-	public ILayerEvent cloneEvent() {
-		return new PropertyUpdateEvent<>(this.layer, this.sourceBean, this.propertyName, this.oldValue, this.newValue);
-	}
-
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		this.layer= localLayer;
-		return true;
-	}
-
-	@Override
-	public Collection<LRectangle> getChangedPositionRectangles() {
-		return Arrays.asList(new LRectangle(0, 0, this.layer.getWidth(), this.layer.getHeight()));
-	}
-
-	@Override
-	public ILayer getLayer() {
-		return this.layer;
-	}
-
-	// Accessors
-
-	public PropertyChangeEvent getPropertyChangeEvent() {
-		return this.propertyChangeEvent;
-	}
-
-	public T getSourceBean() {
-		return this.sourceBean;
-	}
-
-	public String getPropertyName() {
-		return this.propertyName;
-	}
-
-	public Object getNewValue() {
-		return this.newValue;
-	}
-
-	public Object getOldValue() {
-		return this.oldValue;
-	}
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ResizeStructuralRefreshEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ResizeStructuralRefreshEvent.java
deleted file mode 100644
index 77ea7bf4..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/ResizeStructuralRefreshEvent.java
+++ /dev/null
@@ -1,50 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Dirk Fauth and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Dirk Fauth - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import java.util.ArrayList;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-/**
- * Special {@link StructuralRefreshEvent} that returns empty lists for column and 
- * row diffs to avoid complete resetting of changes made to the NatTable by the user
- * (e.g. resetting changed column order like reported in https://bugs.eclipse.org/bugs/show_bug.cgi?id=384795).
- * 
- * <p>This event should only be fired be the {@link DataLayer} if columns or rows are configured
- * to use percentage sizing.
- */
-public class ResizeStructuralRefreshEvent extends StructuralRefreshEvent {
-
-	public ResizeStructuralRefreshEvent(final ILayer layer) {
-		super(layer);
-	}
-
-	protected ResizeStructuralRefreshEvent(final ResizeStructuralRefreshEvent event) {
-		super(event);
-	}
-
-	@Override
-	public Collection<StructuralDiff> getColumnDiffs() {
-		return new ArrayList<>();
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getRowDiffs() {
-		return new ArrayList<>();
-	}
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowStructuralChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowStructuralChangeEvent.java
deleted file mode 100644
index 03ef0d3a..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowStructuralChangeEvent.java
+++ /dev/null
@@ -1,70 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-/**
- * @see ColumnStructuralChangeEvent
- */
-public abstract class RowStructuralChangeEvent extends RowVisualChangeEvent implements IStructuralChangeEvent {
-
-	public RowStructuralChangeEvent(final ILayer layer, final LRange...rowPositionRanges) {
-		this(layer, Arrays.asList(rowPositionRanges));
-	}
-	
-	public RowStructuralChangeEvent(final ILayer layer, final Collection<LRange> rowPositionRanges) {
-		super(layer, rowPositionRanges);
-	}
-	
-	protected RowStructuralChangeEvent(final RowStructuralChangeEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public Collection<LRectangle> getChangedPositionRectangles() {
-		final Collection<LRectangle> changedPositionRectangles= new ArrayList<>();
-		
-		final long columnCount= getLayer().getColumnCount();
-		final long rowCount= getLayer().getRowCount();
-		for (final LRange lRange : getRowPositionRanges()) {
-			changedPositionRectangles.add(new LRectangle(0, lRange.start, columnCount, rowCount - lRange.start));
-		}
-		
-		return changedPositionRectangles;
-	}
-	
-	@Override
-	public boolean isHorizontalStructureChanged() {
-		return false;
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getColumnDiffs() {
-		return null;
-	}
-	
-	@Override
-	public boolean isVerticalStructureChanged() {
-		return true;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowStructuralRefreshEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowStructuralRefreshEvent.java
deleted file mode 100644
index b3b9b621..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowStructuralRefreshEvent.java
+++ /dev/null
@@ -1,37 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-/**
- * @see ColumnStructuralRefreshEvent
- */
-public class RowStructuralRefreshEvent extends StructuralRefreshEvent {
-
-	public RowStructuralRefreshEvent(final ILayer layer) {
-		super(layer);
-	}
-	
-	@Override
-	public boolean isVerticalStructureChanged() {
-		return true;
-	}
-	
-	@Override
-	public boolean isHorizontalStructureChanged() {
-		return false;
-	}
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowUpdateEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowUpdateEvent.java
deleted file mode 100644
index cce92f75..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowUpdateEvent.java
+++ /dev/null
@@ -1,39 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-public class RowUpdateEvent extends RowVisualChangeEvent {
-	
-	public RowUpdateEvent(final ILayer layer, final long rowPosition) {
-		this(layer, new LRange(rowPosition));
-	}
-	
-	public RowUpdateEvent(final ILayer layer, final LRange rowPositionRange) {
-		super(layer, rowPositionRange);
-	}
-	
-	public RowUpdateEvent(final RowUpdateEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public RowUpdateEvent cloneEvent() {
-		return new RowUpdateEvent(this);
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowVisualChangeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowVisualChangeEvent.java
deleted file mode 100644
index 0bf8fd5d..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/RowVisualChangeEvent.java
+++ /dev/null
@@ -1,83 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-public abstract class RowVisualChangeEvent implements IVisualChangeEvent {
-	
-	private ILayer layer;
-	
-	private Collection<LRange> rowPositionRanges= new ArrayList<>();
-	
-	public RowVisualChangeEvent(final ILayer layer, final LRange...rowPositionRanges) {
-		this(layer, Arrays.asList(rowPositionRanges));
-	}
-	
-	public RowVisualChangeEvent(final ILayer layer, final Collection<LRange> rowPositionRanges) {
-		this.layer= layer;
-		this.rowPositionRanges= rowPositionRanges;
-	}
-	
-	// Copy constructor
-	protected RowVisualChangeEvent(final RowVisualChangeEvent event) {
-		this.layer= event.layer;
-		this.rowPositionRanges= event.rowPositionRanges;
-	}
-	
-	@Override
-	public ILayer getLayer() {
-		return this.layer;
-	}
-	
-	public Collection<LRange> getRowPositionRanges() {
-		return this.rowPositionRanges;
-	}
-	
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		this.rowPositionRanges= localLayer.getDim(VERTICAL).underlyingToLocalPositions(
-				this.layer.getDim(VERTICAL), this.rowPositionRanges );
-		this.layer= localLayer;
-		
-		return this.rowPositionRanges != null && this.rowPositionRanges.size() > 0;
-	}
-	
-	@Override
-	public Collection<LRectangle> getChangedPositionRectangles() {
-		final Collection<LRectangle> changedPositionRectangles= new ArrayList<>();
-		
-		final long columnCount= this.layer.getColumnCount();
-		for (final LRange lRange : this.rowPositionRanges) {
-			changedPositionRectangles.add(new LRectangle(0, lRange.start, columnCount, lRange.end - lRange.start));
-		}
-		
-		return changedPositionRectangles;
-	}
-	
-	@Override
-	public String toString() {
-		return getClass().getSimpleName();
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/StructuralRefreshEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/StructuralRefreshEvent.java
deleted file mode 100644
index d3e80d0f..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/StructuralRefreshEvent.java
+++ /dev/null
@@ -1,82 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import java.util.Arrays;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-/**
- * General event indicating that structures cached by the layers need refreshing.
- * <p>
- * TIP: Consider throwing a more focused event (subclass) if you need to do this.
- */
-public class StructuralRefreshEvent implements IStructuralChangeEvent {
-
-	private ILayer layer;
-
-	public StructuralRefreshEvent(final ILayer layer) {
-		this.layer= layer;
-	}
-	
-	protected StructuralRefreshEvent(final StructuralRefreshEvent event) {
-		this.layer= event.layer;
-	}
-	
-	@Override
-	public ILayer getLayer() {
-		return this.layer;
-	}
-
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		this.layer= localLayer;
-		
-		return true;
-	}
-	
-	@Override
-	public Collection<LRectangle> getChangedPositionRectangles() {
-		return Arrays.asList(new LRectangle[] { new LRectangle(0, 0, this.layer.getColumnCount(), this.layer.getRowCount()) });
-	}
-	
-	@Override
-	public boolean isHorizontalStructureChanged() {
-		return true;
-	}
-	
-	@Override
-	public boolean isVerticalStructureChanged() {
-		return true;
-	}
-
-	@Override
-	public Collection<StructuralDiff> getColumnDiffs() {
-		return null;
-	}
-
-	@Override
-	public Collection<StructuralDiff> getRowDiffs() {
-		return null;
-	}
-
-	@Override
-	public ILayerEvent cloneEvent() {
-		return this;
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/VisualRefreshEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/VisualRefreshEvent.java
deleted file mode 100644
index aab43c4d..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/event/VisualRefreshEvent.java
+++ /dev/null
@@ -1,57 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.layer.event;
-
-import java.util.Arrays;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-
-
-public class VisualRefreshEvent implements IVisualChangeEvent {
-
-	private ILayer layer;
-
-	public VisualRefreshEvent(final ILayer layer) {
-		this.layer= layer;
-	}
-	
-	protected VisualRefreshEvent(final VisualRefreshEvent event) {
-		this.layer= event.layer;
-	}
-	
-	@Override
-	public ILayer getLayer() {
-		return this.layer;
-	}
-
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		this.layer= localLayer;
-		
-		return true;
-	}
-	
-	@Override
-	public Collection<LRectangle> getChangedPositionRectangles() {
-		return Arrays.asList(new LRectangle[] { new LRectangle(0, 0, this.layer.getColumnCount(), this.layer.getRowCount()) });
-	}
-	
-	@Override
-	public ILayerEvent cloneEvent() {
-		return new VisualRefreshEvent(this);
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AbstractCellPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AbstractCellPainter.java
index e453d801..c3a6bf0a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AbstractCellPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AbstractCellPainter.java
@@ -15,16 +15,17 @@ package org.eclipse.statet.ecommons.waltable.painter.cell;
 
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 
 
-public abstract class AbstractCellPainter implements ICellPainter {
+public abstract class AbstractCellPainter implements LayerCellPainter {
 
 	@Override
-	public ICellPainter getCellPainterAt(final long x, final long y, final ILayerCell cell, final GC gc,
-			final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public LayerCellPainter getCellPainterAt(final long x, final long y, final LayerCell cell, final GC gc,
+			final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		return this;
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AbstractTextPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AbstractTextPainter.java
index 224a75e5..3c977129 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AbstractTextPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AbstractTextPainter.java
@@ -22,14 +22,14 @@ import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.style.TextDecorationLine;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
 import org.eclipse.statet.ecommons.waltable.layer.cell.CellDisplayConversionUtils;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
-import org.eclipse.statet.ecommons.waltable.style.TextDecorationEnum;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -51,7 +51,7 @@ public abstract class AbstractTextPainter extends BackgroundPainter {
 	 */
 	private static final Pattern NEW_LINE_PATTERN= Pattern.compile("\\n\\r|\\r\\n|\\n|\\r"); //$NON-NLS-1$
 
-	private static final String NEW_LINE_SEPARATOR= System.getProperty("line.separator"); //$NON-NLS-1$
+	private static final String NEW_LINE_SEPARATOR= System.lineSeparator();
 
 	private static final int DEFAULT_SPACING= 3;
 	
@@ -164,9 +164,9 @@ public abstract class AbstractTextPainter extends BackgroundPainter {
 	}
 
 	/**
-	 * Convert the data value of the cell using the {@link IDisplayConverter} from the {@link IConfigRegistry}
+	 * Convert the data value of the cell using the {@link IDisplayConverter} from the {@link ConfigRegistry}
 	 */
-	protected String convertDataType(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	protected String convertDataType(final LayerCell cell, final ConfigRegistry configRegistry) {
 		return CellDisplayConversionUtils.convertDataType(cell, configRegistry);
 	}
 
@@ -175,10 +175,10 @@ public abstract class AbstractTextPainter extends BackgroundPainter {
 	 * @param gc
 	 * @param cellStyle
 	 */
-	protected void setupGCFromConfig(final GC gc, final IStyle cellStyle) {
-		final Color fg= cellStyle.getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR);
-		final Color bg= cellStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
-		final Font font= cellStyle.getAttributeValue(CellStyleAttributes.FONT);
+	protected void setupGCFromConfig(final GC gc, final Style cellStyle) {
+		final Color fg= cellStyle.getAttributeValue(CellStyling.FOREGROUND_COLOR);
+		final Color bg= cellStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR);
+		final Font font= cellStyle.getAttributeValue(CellStyling.FONT);
 
 		gc.setAntialias(GUIHelper.DEFAULT_ANTIALIAS);
 		gc.setTextAntialias(GUIHelper.DEFAULT_TEXT_ANTIALIAS);
@@ -193,11 +193,10 @@ public abstract class AbstractTextPainter extends BackgroundPainter {
 	 * @return <code>true</code> if there is a underline text decoration configured, 
 	 * 			<code>false</code> otherwise.
 	 */
-	protected boolean renderUnderlined(final IStyle cellStyle) {
-		final TextDecorationEnum decoration= cellStyle.getAttributeValue(CellStyleAttributes.TEXT_DECORATION);
-		if (decoration != null) {
-				return (decoration.equals(TextDecorationEnum.UNDERLINE) 
-						|| decoration.equals(TextDecorationEnum.UNDERLINE_STRIKETHROUGH));
+	protected boolean renderUnderlined(final Style cellStyle) {
+		final var lines= cellStyle.getAttributeValue(CellStyling.TEXT_DECORATION_LINES);
+		if (lines != null) {
+			return (lines.contains(TextDecorationLine.UNDERLINE));
 		}
 		return this.underline;
 	}
@@ -208,11 +207,10 @@ public abstract class AbstractTextPainter extends BackgroundPainter {
 	 * @return <code>true</code> if there is a strikethrough text decoration configured, 
 	 * 			<code>false</code> otherwise.
 	 */
-	protected boolean renderStrikethrough(final IStyle cellStyle) {
-		final TextDecorationEnum decoration= cellStyle.getAttributeValue(CellStyleAttributes.TEXT_DECORATION);
-		if (decoration != null) {
-			return (decoration.equals(TextDecorationEnum.STRIKETHROUGH) 
-						|| decoration.equals(TextDecorationEnum.UNDERLINE_STRIKETHROUGH));
+	protected boolean renderStrikethrough(final Style cellStyle) {
+		final var lines= cellStyle.getAttributeValue(CellStyling.TEXT_DECORATION_LINES);
+		if (lines != null) {
+			return (lines.contains(TextDecorationLine.STRIKETHROUGH)); 
 		}
 		return this.strikethrough;
 	}
@@ -274,7 +272,7 @@ public abstract class AbstractTextPainter extends BackgroundPainter {
 	 * @param text the text that should be modified for display
 	 * @return the modified text
 	 */
-	protected String getTextToDisplay(final ILayerCell cell, final GC gc, final long availableLength, String text) {
+	protected String getTextToDisplay(final LayerCell cell, final GC gc, final long availableLength, String text) {
 		final StringBuilder output= new StringBuilder();
 
 		text= text.trim();
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AutomaticRowHeightTextPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AutomaticRowHeightTextPainter.java
index 31ab61fc..65c42942 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AutomaticRowHeightTextPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/AutomaticRowHeightTextPainter.java
@@ -13,8 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.painter.cell;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.data.core.DataLayer;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BackgroundImagePainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BackgroundImagePainter.java
index d06d488e..ce5da6d9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BackgroundImagePainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BackgroundImagePainter.java
@@ -21,9 +21,10 @@ import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Pattern;
 import org.eclipse.swt.widgets.Display;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 
 
 /**
@@ -41,24 +42,24 @@ public class BackgroundImagePainter extends CellPainterWrapper {
 	 * @param separatorColor to be used for drawing left and right borders for the cell.
 	 * 	Set to null if the borders are not required.
 	 */
-	public BackgroundImagePainter(final ICellPainter interiorPainter, final Image bgImage, final Color separatorColor) {
+	public BackgroundImagePainter(final LayerCellPainter interiorPainter, final Image bgImage, final Color separatorColor) {
 		super(interiorPainter);
 		this.bgImage= bgImage;
 		this.separatorColor= separatorColor;
 	}
 
 	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return super.getPreferredWidth(cell, gc, configRegistry) + 4;
 	}
 
 	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return super.getPreferredHeight(cell, gc, configRegistry) + 4;
 	}
 
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle lRectangle, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle lRectangle, final ConfigRegistry configRegistry) {
 		// Save GC settings
 		final Color originalBackground= gc.getBackground();
 		final Color originalForeground= gc.getForeground();
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BackgroundPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BackgroundPainter.java
index dd1a9be9..4b604d5b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BackgroundPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BackgroundPainter.java
@@ -18,17 +18,18 @@ import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.sa
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.ConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
+import org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
 
 
 /**
  * Paints the background of the cell using the color from the cell style.
- * If no background color is registered in the {@link ConfigRegistry} the painting
+ * If no background color is registered in the {@link BasicConfigRegistry} the painting
  * is skipped.
  * <p>
  * Example: The {@link TextPainter} inherits this and uses the paint method
@@ -40,12 +41,12 @@ public class BackgroundPainter extends CellPainterWrapper {
 
 	public BackgroundPainter() {}
 
-	public BackgroundPainter(final ICellPainter painter) {
+	public BackgroundPainter(final LayerCellPainter painter) {
 		super(painter);
 	}
 
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle bounds, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle bounds, final ConfigRegistry configRegistry) {
 		final Color backgroundColor= getBackgroundColour(cell, configRegistry);
 		if (backgroundColor != null) {
 			final Color originalBackground= gc.getBackground();
@@ -59,8 +60,8 @@ public class BackgroundPainter extends CellPainterWrapper {
 		super.paintCell(cell, gc, bounds, configRegistry);
 	}
 	
-	protected Color getBackgroundColour(final ILayerCell cell, final IConfigRegistry configRegistry) {
-		return CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
+	protected Color getBackgroundColour(final LayerCell cell, final ConfigRegistry configRegistry) {
+		return CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyling.BACKGROUND_COLOR);
 	}
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BlendedBackgroundPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BlendedBackgroundPainter.java
index aa44ca7f..62834ca7 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BlendedBackgroundPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/BlendedBackgroundPainter.java
@@ -18,13 +18,14 @@ import java.util.List;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.RGB;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleProxy;
+import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.RegistryStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -56,7 +57,7 @@ public class BlendedBackgroundPainter extends TextPainter {
 	}
 
 	@Override
-	protected Color getBackgroundColour(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	protected Color getBackgroundColour(final LayerCell cell, final ConfigRegistry configRegistry) {
 		return blendBackgroundColour(cell, configRegistry, this.gridBackgroundColour);
 	}
 
@@ -65,22 +66,23 @@ public class BlendedBackgroundPainter extends TextPainter {
 	 * have been registered, they are all blended together.
 	 *
 	 * @param cell
-	 *            the {@link org.eclipse.statet.ecommons.waltable.layer.cell.ForwardLayerCell} to get a background colour for.
+	 *            the {@link org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerCell} to get a background colour for.
 	 * @param configRegistry
-	 *            an {@link org.eclipse.statet.ecommons.waltable.config.IConfigRegistry}.
+	 *            an {@link org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry}.
 	 * @param baseColor
 	 *            Colours are not blended with this colour.
 	 * @return A blended background colour.
 	 */
-	public static Color blendBackgroundColour(final ILayerCell cell, final IConfigRegistry configRegistry, final RGB baseColor) {
+	public static Color blendBackgroundColour(final LayerCell cell, final ConfigRegistry configRegistry, final RGB baseColor) {
 
 		// Get all of the background colours registered for the cell in normal mode.
 		final List<Color> colours= CellStyleUtil.getAllBackgroundColors(cell, configRegistry, DisplayMode.NORMAL);
 
 		// If the cell is selected, get it's selected background colour and add to the blending mix.
-		if (cell.getDisplayMode().equals(DisplayMode.SELECT)) {
-			final IStyle cellStyle= new CellStyleProxy(configRegistry, DisplayMode.SELECT, cell.getConfigLabels().getLabels());
-			colours.add(cellStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR));
+		if (cell.getDisplayMode().equals(DisplayMode.SELECTED)) {
+			final Style cellStyle= new RegistryStyle(configRegistry, CellConfigAttributes.CELL_STYLE,
+					DisplayMode.SELECTED, cell.getLabels().getLabels());
+			colours.add(cellStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR));
 		}
 
 		if (colours.size() == 0) {
@@ -102,7 +104,7 @@ public class BlendedBackgroundPainter extends TextPainter {
 				}
 			}
 
-			return GUIHelper.getColor(rgb);
+			return new Color(rgb);
 		}
 	}
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ButtonCellPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ButtonCellPainter.java
index b3acc9ea..4935404f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ButtonCellPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ButtonCellPainter.java
@@ -23,11 +23,12 @@ import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.widgets.Display;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.event.CellVisualChangeEvent;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.CellVisualChangeEvent;
 import org.eclipse.statet.ecommons.waltable.painter.cell.decorator.BeveledBorderDecorator;
 import org.eclipse.statet.ecommons.waltable.ui.NatEventData;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
@@ -37,8 +38,8 @@ import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
  * Paints a button and simulates a button click. It also notifies its listeners when it is clicked.  
  */
 public class ButtonCellPainter extends AbstractCellPainter implements IMouseAction {
-	private final ICellPainter buttonRaisedPainter;
-	private final ICellPainter buttonPressedPainter;
+	private final LayerCellPainter buttonRaisedPainter;
+	private final LayerCellPainter buttonPressedPainter;
 
 	private int buttonFlashTime= 150;
 
@@ -51,7 +52,7 @@ public class ButtonCellPainter extends AbstractCellPainter implements IMouseActi
 	 * @param interiorPainter to paint the contents of the cell. 
 	 * 	This will be decorated with a button like look and feel. 
 	 */
-	public ButtonCellPainter(final ICellPainter interiorPainter) {
+	public ButtonCellPainter(final LayerCellPainter interiorPainter) {
 		this.buttonPressedPainter= new BeveledBorderDecorator(interiorPainter, false);
 		this.buttonRaisedPainter= new BeveledBorderDecorator(interiorPainter);
 	}
@@ -60,13 +61,13 @@ public class ButtonCellPainter extends AbstractCellPainter implements IMouseActi
 	 * @param buttonRaisedPainter cell painter to use for painting the button raised state.
 	 * @param buttonPressedPainter cell painter to use for painting the button pressed state.
 	 */
-	public ButtonCellPainter(final ICellPainter buttonRaisedPainter, final ICellPainter buttonPressedPainter) {
+	public ButtonCellPainter(final LayerCellPainter buttonRaisedPainter, final LayerCellPainter buttonPressedPainter) {
 		this.buttonRaisedPainter= buttonRaisedPainter;
 		this.buttonPressedPainter= buttonPressedPainter;
 	}
 
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle bounds, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle bounds, final ConfigRegistry configRegistry) {
 		if (this.recentlyClicked && this.columnPosClicked == cell.getColumnPosition() && this.rowPosClicked == cell.getRowPosition()){
 			this.buttonPressedPainter.paintCell(cell, gc, bounds, configRegistry);
 		} else {
@@ -75,16 +76,16 @@ public class ButtonCellPainter extends AbstractCellPainter implements IMouseActi
 	}
 
 	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return cell.getBounds().height;
 	}
 
 	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return cell.getBounds().width;
 	}
 
-	private TimerTask getButtonFlashTimerTask(final ILayer layer){
+	private TimerTask getButtonFlashTimerTask(final Layer layer){
 		return new TimerTask() {
 			@Override
 			public void run() {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/CellPainterWrapper.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/CellPainterWrapper.java
index 41218d4e..1eb5563d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/CellPainterWrapper.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/CellPainterWrapper.java
@@ -15,35 +15,36 @@ package org.eclipse.statet.ecommons.waltable.painter.cell;
 
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 
 
 public abstract class CellPainterWrapper extends AbstractCellPainter {
 
-	private ICellPainter wrappedPainter;
+	private LayerCellPainter wrappedPainter;
 
 	public CellPainterWrapper() {}
 
-	public CellPainterWrapper(final ICellPainter painter) {
+	public CellPainterWrapper(final LayerCellPainter painter) {
 		this.wrappedPainter= painter;
 	}
 
-	public void setWrappedPainter(final ICellPainter painter) {
+	public void setWrappedPainter(final LayerCellPainter painter) {
 		this.wrappedPainter= painter;
 	}
 
-	public ICellPainter getWrappedPainter() {
+	public LayerCellPainter getWrappedPainter() {
 		return this.wrappedPainter;
 	}
 
-	public LRectangle getWrappedPainterBounds(final ILayerCell cell, final GC gc, final LRectangle bounds, final IConfigRegistry configRegistry) {
+	public LRectangle getWrappedPainterBounds(final LayerCell cell, final GC gc, final LRectangle bounds, final ConfigRegistry configRegistry) {
 		return bounds;
 	}
 
 	@Override
-	public ICellPainter getCellPainterAt(final long x, final long y, final ILayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public LayerCellPainter getCellPainterAt(final long x, final long y, final LayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		final LRectangle wrappedPainterBounds= getWrappedPainterBounds(cell, gc, adjustedCellBounds, configRegistry);
 		if (this.wrappedPainter != null && wrappedPainterBounds.contains(x, y)) {
 			return this.wrappedPainter.getCellPainterAt(x, y, cell, gc, wrappedPainterBounds, configRegistry);
@@ -53,17 +54,17 @@ public abstract class CellPainterWrapper extends AbstractCellPainter {
 	}
 
 	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return this.wrappedPainter != null ? this.wrappedPainter.getPreferredWidth(cell, gc, configRegistry) : 0;
 	}
 
 	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return this.wrappedPainter != null ? this.wrappedPainter.getPreferredHeight(cell, gc, configRegistry) : 0;
 	}
 
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		if (this.wrappedPainter != null) {
 			this.wrappedPainter.paintCell(cell, gc, adjustedCellBounds, configRegistry);
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/CheckBoxPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/CheckBoxPainter.java
index 054ca81e..936f539a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/CheckBoxPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/CheckBoxPainter.java
@@ -16,9 +16,9 @@ package org.eclipse.statet.ecommons.waltable.painter.cell;
 import org.eclipse.swt.graphics.Image;
 
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -47,19 +47,19 @@ public class CheckBoxPainter extends ImagePainter {
 	}
 
 	@Override
-	protected Image getImage(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	protected Image getImage(final LayerCell cell, final ConfigRegistry configRegistry) {
 		return isChecked(cell, configRegistry) ? this.checkedImg : this.uncheckedImg;
 	}
 
-	protected boolean isChecked(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	protected boolean isChecked(final LayerCell cell, final ConfigRegistry configRegistry) {
 		return convertDataType(cell, configRegistry).booleanValue();
 	}
 
-	protected Boolean convertDataType(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	protected Boolean convertDataType(final LayerCell cell, final ConfigRegistry configRegistry) {
 		if (cell.getDataValue(0, null) instanceof Boolean) {
 			return (Boolean) cell.getDataValue(0, null);
 		}
-		final IDisplayConverter displayConverter= configRegistry.getConfigAttribute(CellConfigAttributes.DISPLAY_CONVERTER, cell.getDisplayMode(), cell.getConfigLabels().getLabels());
+		final IDisplayConverter displayConverter= configRegistry.getAttribute(CellConfigAttributes.DISPLAY_CONVERTER, cell.getDisplayMode(), cell.getLabels().getLabels());
 		Boolean convertedValue= null;
 		if (displayConverter != null) {
 			convertedValue= (Boolean) displayConverter.canonicalToDisplayValue(cell, configRegistry, cell.getDataValue(0, null));
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ColumnHeaderCheckBoxPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ColumnHeaderCheckBoxPainter.java
index 7ce2f68c..d2612d8e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ColumnHeaderCheckBoxPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ColumnHeaderCheckBoxPainter.java
@@ -16,11 +16,11 @@ package org.eclipse.statet.ecommons.waltable.painter.cell;
 import org.eclipse.swt.graphics.Image;
 
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerUtils;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LayerUtil;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -31,9 +31,9 @@ public class ColumnHeaderCheckBoxPainter extends ImagePainter {
 	private final Image semicheckedImg;
 	private final Image uncheckedImg;
 	
-	private final ILayer columnDataLayer;
+	private final Layer columnDataLayer;
 
-	public ColumnHeaderCheckBoxPainter(final ILayer columnDataLayer) {
+	public ColumnHeaderCheckBoxPainter(final Layer columnDataLayer) {
 		this(
 				columnDataLayer,
 				GUIHelper.getImage("checked"), //$NON-NLS-1$
@@ -42,7 +42,7 @@ public class ColumnHeaderCheckBoxPainter extends ImagePainter {
 		);
 	}
 
-	public ColumnHeaderCheckBoxPainter(final ILayer columnLayer, final Image checkedImg, final Image semicheckedImage, final Image uncheckedImg) {
+	public ColumnHeaderCheckBoxPainter(final Layer columnLayer, final Image checkedImg, final Image semicheckedImage, final Image uncheckedImg) {
 		this.columnDataLayer= columnLayer;
 		this.checkedImg= checkedImg;
 		this.semicheckedImg= semicheckedImage;
@@ -58,8 +58,8 @@ public class ColumnHeaderCheckBoxPainter extends ImagePainter {
 	}
 
 	@Override
-	protected Image getImage(final ILayerCell cell, final IConfigRegistry configRegistry) {
-		final long columnPosition= LayerUtil.convertColumnPosition(cell.getLayer(), cell.getColumnPosition(), this.columnDataLayer);
+	protected Image getImage(final LayerCell cell, final ConfigRegistry configRegistry) {
+		final long columnPosition= LayerUtils.convertColumnPosition(cell.getLayer(), cell.getColumnPosition(), this.columnDataLayer);
 		
 		final long checkedCellsCount= getCheckedCellsCount(columnPosition, configRegistry);
 		
@@ -74,11 +74,11 @@ public class ColumnHeaderCheckBoxPainter extends ImagePainter {
 		}
 	}
 
-	public long getCheckedCellsCount(final long columnPosition, final IConfigRegistry configRegistry) {
+	public long getCheckedCellsCount(final long columnPosition, final ConfigRegistry configRegistry) {
 		long checkedCellsCount= 0;
 		
 		for (long rowPosition= 0; rowPosition < this.columnDataLayer.getRowCount(); rowPosition++) {
-			final ILayerCell columnCell= this.columnDataLayer.getCellByPosition(columnPosition, rowPosition);
+			final LayerCell columnCell= this.columnDataLayer.getCellByPosition(columnPosition, rowPosition);
 			if (isChecked(columnCell, configRegistry)) {
 				checkedCellsCount++;
 			}
@@ -86,15 +86,15 @@ public class ColumnHeaderCheckBoxPainter extends ImagePainter {
 		return checkedCellsCount;
 	}
 
-	protected boolean isChecked(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	protected boolean isChecked(final LayerCell cell, final ConfigRegistry configRegistry) {
 		return convertDataType(cell, configRegistry).booleanValue();
 	}
 
-	protected Boolean convertDataType(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	protected Boolean convertDataType(final LayerCell cell, final ConfigRegistry configRegistry) {
 		if (cell.getDataValue(0, null) instanceof Boolean) {
 			return (Boolean) cell.getDataValue(0, null);
 		}
-		final IDisplayConverter displayConverter= configRegistry.getConfigAttribute(CellConfigAttributes.DISPLAY_CONVERTER, cell.getDisplayMode(), cell.getConfigLabels().getLabels());
+		final IDisplayConverter displayConverter= configRegistry.getAttribute(CellConfigAttributes.DISPLAY_CONVERTER, cell.getDisplayMode(), cell.getLabels().getLabels());
 		Boolean convertedValue= null;
 		if (displayConverter != null) {
 			try {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/DiagCellPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/DiagCellPainter.java
index 2d21683b..1405a78d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/DiagCellPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/DiagCellPainter.java
@@ -20,9 +20,9 @@ import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -41,7 +41,7 @@ public class DiagCellPainter extends BackgroundPainter {
 	
 	
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle bounds, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle bounds, final ConfigRegistry configRegistry) {
 		super.paintCell(cell, gc, bounds, configRegistry);
 		
 		gc.setForeground(this.color);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/GradientBackgroundPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/GradientBackgroundPainter.java
index e9b1874f..b2c88f29 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/GradientBackgroundPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/GradientBackgroundPainter.java
@@ -15,24 +15,26 @@ package org.eclipse.statet.ecommons.waltable.painter.cell;
 
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
+import org.eclipse.swt.graphics.Rectangle;
 
-import org.eclipse.statet.ecommons.waltable.config.ConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
+import org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
 
 
 /**
  * Paints the background of the cell with a gradient sweeping using the style configuration.
  * To configure the gradient sweeping the following style attributes need to be configured
- * in the {@link ConfigRegistry}: 
+ * in the {@link BasicConfigRegistry}: 
  * <ul>
- * 	<li>{@link CellStyleAttributes#GRADIENT_FOREGROUND_COLOR} or {@link CellStyleAttributes#FOREGROUND_COLOR}</li>
- * 	<li>{@link CellStyleAttributes#GRADIENT_BACKGROUND_COLOR} or {@link CellStyleAttributes#BACKGROUND_COLOR}</li>
+ * 	<li>{@link CellStyling#GRADIENT_FOREGROUND_COLOR} or {@link CellStyling#FOREGROUND_COLOR}</li>
+ * 	<li>{@link CellStyling#GRADIENT_BACKGROUND_COLOR} or {@link CellStyling#BACKGROUND_COLOR}</li>
  * </ul>
- * If none of these values are registered in the {@link ConfigRegistry} the painting is skipped.
+ * If none of these values are registered in the {@link BasicConfigRegistry} the painting is skipped.
  * <p>
  * Can be used as a cell painter or a decorator.
  */
@@ -65,26 +67,26 @@ public class GradientBackgroundPainter extends CellPainterWrapper {
 	/**
 	 * Creates a {@link GradientBackgroundPainter} as wrapper for the given painter with a gradient sweeping from
 	 * left to right.
-	 * @param painter The {@link ICellPainter} that is wrapped by this {@link GradientBackgroundPainter}
+	 * @param painter The {@link LayerCellPainter} that is wrapped by this {@link GradientBackgroundPainter}
 	 */
-	public GradientBackgroundPainter(final ICellPainter painter) {
+	public GradientBackgroundPainter(final LayerCellPainter painter) {
 		this(painter, false);
 	}
 
 	/**
 	 * Creates a {@link GradientBackgroundPainter} as wrapper for the given painter where the sweeping direction
 	 * can be set.
-	 * @param painter The {@link ICellPainter} that is wrapped by this {@link GradientBackgroundPainter}
+	 * @param painter The {@link LayerCellPainter} that is wrapped by this {@link GradientBackgroundPainter}
 	 * @param vertical if <code>true</code> sweeps from top to bottom, else 
 	 *        sweeps from left to right. <code>false</code> is default
 	 */
-	public GradientBackgroundPainter(final ICellPainter painter, final boolean vertical) {
+	public GradientBackgroundPainter(final LayerCellPainter painter, final boolean vertical) {
 		super(painter);
 		this.vertical= vertical;
 	}
 
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle bounds, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle bounds, final ConfigRegistry configRegistry) {
 		final Color foregroundColor= getForeGroundColour(cell, configRegistry);
 		final Color backgroundColor= getBackgroundColour(cell, configRegistry);
 		if (backgroundColor != null && foregroundColor != null) {
@@ -93,7 +95,7 @@ public class GradientBackgroundPainter extends CellPainterWrapper {
 
 			gc.setForeground(foregroundColor);
 			gc.setBackground(backgroundColor);
-			final org.eclipse.swt.graphics.Rectangle rect= GraphicsUtils.safe(bounds);
+			final Rectangle rect= GraphicsUtils.safe(bounds);
 			gc.fillGradientRectangle(rect.x, rect.y, rect.width, rect.height, this.vertical);
 
 			gc.setForeground(originalForeground);
@@ -104,33 +106,33 @@ public class GradientBackgroundPainter extends CellPainterWrapper {
 	}
 	
 	/**
-	 * Searches the foreground color to be used for gradient sweeping. First checks the {@link org.eclipse.statet.ecommons.waltable.config.ConfigRegistry} if there
-	 * is a value for the attribute {@link CellStyleAttributes#GRADIENT_FOREGROUND_COLOR} is registered. If there is one
-	 * this value will be returned, if not it is checked if there is a value registered for {@link CellStyleAttributes#FOREGROUND_COLOR}
+	 * Searches the foreground color to be used for gradient sweeping. First checks the {@link org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry} if there
+	 * is a value for the attribute {@link CellStyling#GRADIENT_FOREGROUND_COLOR} is registered. If there is one
+	 * this value will be returned, if not it is checked if there is a value registered for {@link CellStyling#FOREGROUND_COLOR}
 	 * and returned. If there is no value registered for any of these attributes, <code>null</code> will be returned which
 	 * will skip the painting.
-	 * @param cell The {@link org.eclipse.statet.ecommons.waltable.layer.cell.ForwardLayerCell} for which the style attributes should be retrieved out of the {@link org.eclipse.statet.ecommons.waltable.config.ConfigRegistry}
-	 * @param configRegistry The {@link org.eclipse.statet.ecommons.waltable.config.ConfigRegistry} to retrieve the attribute values from.
+	 * @param cell The {@link org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerCell} for which the style attributes should be retrieved out of the {@link org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry}
+	 * @param configRegistry The {@link org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry} to retrieve the attribute values from.
 	 * @return The {@link Color} to use as foreground color of the gradient sweeping or <code>null</code> if none was configured.
 	 */
-	protected Color getForeGroundColour(final ILayerCell cell, final IConfigRegistry configRegistry) {
-		final Color fgColor= CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyleAttributes.GRADIENT_FOREGROUND_COLOR);
-		return fgColor != null ? fgColor : CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR);
+	protected Color getForeGroundColour(final LayerCell cell, final ConfigRegistry configRegistry) {
+		final Color fgColor= CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyling.GRADIENT_FOREGROUND_COLOR);
+		return fgColor != null ? fgColor : CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyling.FOREGROUND_COLOR);
 	}
 	
 	/**
-	 * Searches the background color to be used for gradient sweeping. First checks the {@link org.eclipse.statet.ecommons.waltable.config.ConfigRegistry} if there
-	 * is a value for the attribute {@link CellStyleAttributes#GRADIENT_BACKGROUND_COLOR} is registered. If there is one
-	 * this value will be returned, if not it is checked if there is a value registered for {@link CellStyleAttributes#BACKGROUND_COLOR}
+	 * Searches the background color to be used for gradient sweeping. First checks the {@link org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry} if there
+	 * is a value for the attribute {@link CellStyling#GRADIENT_BACKGROUND_COLOR} is registered. If there is one
+	 * this value will be returned, if not it is checked if there is a value registered for {@link CellStyling#BACKGROUND_COLOR}
 	 * and returned. If there is no value registered for any of these attributes, <code>null</code> will be returned which
 	 * will skip the painting.
-	 * @param cell The {@link org.eclipse.statet.ecommons.waltable.layer.cell.ForwardLayerCell} for which the style attributes should be retrieved out of the {@link org.eclipse.statet.ecommons.waltable.config.ConfigRegistry}
-	 * @param configRegistry The {@link org.eclipse.statet.ecommons.waltable.config.ConfigRegistry} to retrieve the attribute values from.
+	 * @param cell The {@link org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerCell} for which the style attributes should be retrieved out of the {@link org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry}
+	 * @param configRegistry The {@link org.eclipse.statet.ecommons.waltable.core.config.BasicConfigRegistry} to retrieve the attribute values from.
 	 * @return The {@link Color} to use as background color of the gradient sweeping or <code>null</code> if none was configured.
 	 */
-	protected Color getBackgroundColour(final ILayerCell cell, final IConfigRegistry configRegistry) {
-		final Color bgColor= CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyleAttributes.GRADIENT_BACKGROUND_COLOR);
-		return bgColor != null ? bgColor : CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
+	protected Color getBackgroundColour(final LayerCell cell, final ConfigRegistry configRegistry) {
+		final Color bgColor= CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyling.GRADIENT_BACKGROUND_COLOR);
+		return bgColor != null ? bgColor : CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyling.BACKGROUND_COLOR);
 	}
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/GraphicsUtils.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/GraphicsUtils.java
index cff1e2d0..d7f3cb75 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/GraphicsUtils.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/GraphicsUtils.java
@@ -23,6 +23,8 @@ import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Display;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+
 
 /**
  * This class contains utility methods for drawing graphics
@@ -32,13 +34,6 @@ import org.eclipse.swt.widgets.Display;
 public class GraphicsUtils {
 	
 	
-	public static final int check(final long pixel) {
-		if (pixel < Integer.MIN_VALUE || pixel > Integer.MAX_VALUE) {
-			throw new IndexOutOfBoundsException();
-		}
-		return (int) pixel;
-	}
-	
 	public static final int safe(final long pixel) {
 		return (pixel <= Integer.MIN_VALUE) ? Integer.MIN_VALUE :
 			((pixel >= Integer.MAX_VALUE) ? Integer.MAX_VALUE : (int) pixel);
@@ -50,7 +45,7 @@ public class GraphicsUtils {
 		return new Rectangle(sx, sy, safe(x + width) - sx, safe(y + height) - sy);
 	}
 	
-	public static final Rectangle safe(final org.eclipse.statet.ecommons.waltable.coordinate.LRectangle rect) {
+	public static final Rectangle safe(final LRectangle rect) {
 		return safe(rect.x, rect.y, rect.width, rect.height);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ImagePainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ImagePainter.java
index a05997de..8f6e8f31 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ImagePainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/ImagePainter.java
@@ -17,13 +17,15 @@ import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.sa
 
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Image;
+import org.eclipse.swt.graphics.Rectangle;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
 
 
 /**
@@ -48,7 +50,7 @@ public class ImagePainter extends BackgroundPainter {
 	}
 
 	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		final Image image= getImage(cell, configRegistry);
 		if (image != null) {
 			return image.getBounds().width;
@@ -58,7 +60,7 @@ public class ImagePainter extends BackgroundPainter {
 	}
 
 	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		final Image image= getImage(cell, configRegistry);
 		if (image != null) {
 			return image.getBounds().height;
@@ -68,11 +70,11 @@ public class ImagePainter extends BackgroundPainter {
 	}
 
 	@Override
-	public ICellPainter getCellPainterAt(final long x, final long y, final ILayerCell cell, final GC gc, final LRectangle bounds, final IConfigRegistry configRegistry) {
+	public LayerCellPainter getCellPainterAt(final long x, final long y, final LayerCell cell, final GC gc, final LRectangle bounds, final ConfigRegistry configRegistry) {
 		final Image image= getImage(cell, configRegistry);
 		if (image != null) {
-			final org.eclipse.swt.graphics.Rectangle imageBounds= image.getBounds();
-			final IStyle cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
+			final Rectangle imageBounds= image.getBounds();
+			final Style cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
 			final long x0= bounds.x + CellStyleUtil.getHorizontalAlignmentPadding(cellStyle, bounds, imageBounds.width);
 			final long y0= bounds.y + CellStyleUtil.getVerticalAlignmentPadding(cellStyle, bounds, imageBounds.height);
 			if (	x >= x0 &&
@@ -86,23 +88,23 @@ public class ImagePainter extends BackgroundPainter {
 	}
 	
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle bounds, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle bounds, final ConfigRegistry configRegistry) {
 		if (this.paintBg) {
 			super.paintCell(cell, gc, bounds, configRegistry);
 		}
 
 		final Image image= getImage(cell, configRegistry);
 		if (image != null) {
-			final org.eclipse.swt.graphics.Rectangle imageBounds= image.getBounds();
-			final IStyle cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
+			final Rectangle imageBounds= image.getBounds();
+			final Style cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
 			gc.drawImage(image,
 					safe(bounds.x + CellStyleUtil.getHorizontalAlignmentPadding(cellStyle, bounds, imageBounds.width)),
 					safe(bounds.y + CellStyleUtil.getVerticalAlignmentPadding(cellStyle, bounds, imageBounds.height)));
 		}
 	}
 	
-	protected Image getImage(final ILayerCell cell, final IConfigRegistry configRegistry) {
-		return this.image != null ? this.image : CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyleAttributes.IMAGE);
+	protected Image getImage(final LayerCell cell, final ConfigRegistry configRegistry) {
+		return this.image != null ? this.image : CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyling.IMAGE);
 	}
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/PasswordTextPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/PasswordTextPainter.java
index f88cb257..54026a4b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/PasswordTextPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/PasswordTextPainter.java
@@ -15,20 +15,20 @@ package org.eclipse.statet.ecommons.waltable.painter.cell;
 
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
 import org.eclipse.statet.ecommons.waltable.edit.editor.PasswordCellEditor;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
 
 
 /**
  * Specialized {@link TextPainter} that will paint the text that should be showed within
  * a cell anonymized. Like in {@link PasswordCellEditor} every character will be replaced 
  * with another echo character. The echo character can be configured by setting the 
- * attribute {@link CellStyleAttributes#PASSWORD_ECHO_CHAR} to the cell style to use. 
+ * attribute {@link CellStyling#PASSWORD_ECHO_CHAR} to the cell style to use. 
  * If no echo character is configured, the bullet character will be used as echo character.
  * 
  * @see PasswordCellEditor
@@ -66,10 +66,10 @@ public class PasswordTextPainter extends TextPainter {
 
 	
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle lRectangle, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle lRectangle, final ConfigRegistry configRegistry) {
 		//check for the configuration of a echo character in the corresponding cell style
-		final IStyle cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
-		final Character configEchoChar= cellStyle.getAttributeValue(CellStyleAttributes.PASSWORD_ECHO_CHAR);
+		final Style cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
+		final Character configEchoChar= cellStyle.getAttributeValue(CellStyling.PASSWORD_ECHO_CHAR);
 		if (configEchoChar != null) {
 			this.echoChar= configEchoChar;
 		}
@@ -77,7 +77,7 @@ public class PasswordTextPainter extends TextPainter {
 	}
 	
 	@Override
-	protected String getTextToDisplay(final ILayerCell cell, final GC gc, final long availableLength, final String text) {
+	protected String getTextToDisplay(final LayerCell cell, final GC gc, final long availableLength, final String text) {
 		final String result= super.getTextToDisplay(cell, gc, availableLength, text);
 		//replace all characters with the configured echo character
 		return result.replaceAll(".", this.echoChar.toString()); //$NON-NLS-1$
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/PercentageBarCellPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/PercentageBarCellPainter.java
index 541f3add..b0f348d3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/PercentageBarCellPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/PercentageBarCellPainter.java
@@ -13,10 +13,12 @@
 
 package org.eclipse.statet.ecommons.waltable.painter.cell;
 
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle.LineStyle;
 import org.eclipse.statet.ecommons.waltable.painter.cell.decorator.LineBorderDecorator;
 import org.eclipse.statet.ecommons.waltable.painter.cell.decorator.PaddingDecorator;
 import org.eclipse.statet.ecommons.waltable.painter.cell.decorator.PercentageBarDecorator;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
 public class PercentageBarCellPainter extends CellPainterWrapper {
@@ -26,6 +28,8 @@ public class PercentageBarCellPainter extends CellPainterWrapper {
     }
 
     public PercentageBarCellPainter(final long outerPadding) {
-        super(new PaddingDecorator(new LineBorderDecorator(new PercentageBarDecorator(new TextPainter(false, false)), new BorderStyle()), outerPadding));
+        super(new PaddingDecorator(new LineBorderDecorator(new PercentageBarDecorator(new TextPainter(false, false)),
+        		new BorderStyle(1, GUIHelper.COLOR_BLACK, LineStyle.SOLID)),
+        		outerPadding));
     }
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/TextPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/TextPainter.java
index 62a4a276..826bebf0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/TextPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/TextPainter.java
@@ -13,19 +13,20 @@
 
 package org.eclipse.statet.ecommons.waltable.painter.cell;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
 
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.GC;
+import org.eclipse.swt.graphics.Rectangle;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.resize.DimPositionResizeCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.resize.core.DimPositionResizeCommand;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
 
 
 /**
@@ -93,29 +94,29 @@ public class TextPainter extends AbstractTextPainter {
 	
 	
 	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry){
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry){
 		setupGCFromConfig(gc, CellStyleUtil.getCellStyle(cell, configRegistry));
 		return getWidthFromCache(gc, convertDataType(cell, configRegistry)) + (this.spacing*2) + 1;
 	}
 
 	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		setupGCFromConfig(gc, CellStyleUtil.getCellStyle(cell, configRegistry));
 		return gc.textExtent(convertDataType(cell, configRegistry)).y + (this.spacing*2) + 1;
 	}
 
 
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle lRectangle, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle lRectangle, final ConfigRegistry configRegistry) {
 		if (this.paintBg) {
 			super.paintCell(cell, gc, lRectangle, configRegistry);
 		}
 
 		if (this.paintFg) {
-			final org.eclipse.swt.graphics.Rectangle originalClipping= gc.getClipping();
+			final Rectangle originalClipping= gc.getClipping();
 			gc.setClipping(safe(lRectangle).intersection(originalClipping));
 	
-			final IStyle cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
+			final Style cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
 			setupGCFromConfig(gc, cellStyle);
 			
 			final boolean underline= renderUnderlined(cellStyle);
@@ -135,7 +136,7 @@ public class TextPainter extends AbstractTextPainter {
 			final long contentToCellDiff= (cell.getBounds().height - lRectangle.height);
 	
 			if (performRowResize(contentHeight, lRectangle)) {
-				final ILayer layer= cell.getLayer();
+				final Layer layer= cell.getLayer();
 				layer.doCommand(new DimPositionResizeCommand(layer.getDim(VERTICAL), 
 						cell.getRowPosition(), 
 						(int) Math.min(contentHeight + contentToCellDiff, 0x7fff) ));
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/TreeCheckBoxPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/TreeCheckBoxPainter.java
index 9b45b600..a8ec71dd 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/TreeCheckBoxPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/TreeCheckBoxPainter.java
@@ -15,9 +15,9 @@ package org.eclipse.statet.ecommons.waltable.painter.cell;
 
 import org.eclipse.swt.graphics.Image;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.edit.CheckBoxStateEnum;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -50,7 +50,7 @@ public abstract class TreeCheckBoxPainter extends ImagePainter {
 	}
 
 	@Override
-	protected Image getImage(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	protected Image getImage(final LayerCell cell, final ConfigRegistry configRegistry) {
 		switch (getCheckBoxState(cell)) {
 		case CHECKED:
 			return this.checkedImg;
@@ -61,6 +61,6 @@ public abstract class TreeCheckBoxPainter extends ImagePainter {
 		}
 	}
 	
-	protected abstract CheckBoxStateEnum getCheckBoxState(ILayerCell cell);
+	protected abstract CheckBoxStateEnum getCheckBoxState(LayerCell cell);
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/BeveledBorderDecorator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/BeveledBorderDecorator.java
index d51dec1c..72f12e0e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/BeveledBorderDecorator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/BeveledBorderDecorator.java
@@ -17,12 +17,13 @@ import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.sa
 
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
+import org.eclipse.swt.graphics.Rectangle;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.CellPainterWrapper;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -42,7 +43,7 @@ public class BeveledBorderDecorator extends CellPainterWrapper {
 	 * 
 	 * @param interiorPainter The painter which should be wrapped by this decorator.
 	 */
-	public BeveledBorderDecorator(final ICellPainter interiorPainter) {
+	public BeveledBorderDecorator(final LayerCellPainter interiorPainter) {
 		super(interiorPainter);
 	}
 
@@ -53,28 +54,28 @@ public class BeveledBorderDecorator extends CellPainterWrapper {
 	 * 			By default this flag is set to <code>true</code>. Set it to <code>false</code> if
 	 * 			the cell should be rendered sunk.
 	 */
-	public BeveledBorderDecorator(final ICellPainter interiorPainter, final boolean uplift) {
+	public BeveledBorderDecorator(final LayerCellPainter interiorPainter, final boolean uplift) {
 		super(interiorPainter);
 		this.uplift= uplift;
 	}
 	
 	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return super.getPreferredWidth(cell, gc, configRegistry) + 4;
 	}
 	
 	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return super.getPreferredHeight(cell, gc, configRegistry) + 4;
 	}
 
 	@Override
-	public LRectangle getWrappedPainterBounds(final ILayerCell cell, final GC gc, final LRectangle bounds, final IConfigRegistry configRegistry) {
+	public LRectangle getWrappedPainterBounds(final LayerCell cell, final GC gc, final LRectangle bounds, final ConfigRegistry configRegistry) {
 		return new LRectangle(bounds.x + 2, bounds.y + 2, bounds.width - 4, bounds.height - 4);
 	}
 	
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		final LRectangle interiorBounds= getWrappedPainterBounds(cell, gc, adjustedCellBounds, configRegistry);
 		super.paintCell(cell, gc, interiorBounds, configRegistry);
 		
@@ -83,7 +84,7 @@ public class BeveledBorderDecorator extends CellPainterWrapper {
 		
 		//TODO: Need to look at the border style
 		
-		final org.eclipse.swt.graphics.Rectangle rect= safe(adjustedCellBounds);
+		final Rectangle rect= safe(adjustedCellBounds);
 		// Up
 		gc.setForeground(this.uplift ? GUIHelper.COLOR_WIDGET_LIGHT_SHADOW : GUIHelper.COLOR_WIDGET_DARK_SHADOW);
 		gc.drawLine(rect.x, rect.y, rect.x + rect.width - 1, rect.y);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/CellPainterDecorator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/CellPainterDecorator.java
index c3fb9880..60141c45 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/CellPainterDecorator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/CellPainterDecorator.java
@@ -18,11 +18,11 @@ import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.sa
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
 import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeEnum;
 
@@ -30,20 +30,20 @@ import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeEnum;
 /**
  * Decorates a cell painter with another cell painter.
  */
-public class CellPainterDecorator implements ICellPainter {
+public class CellPainterDecorator implements LayerCellPainter {
 
 	/**
-	 * The base {@link ICellPainter} that is decorated.
+	 * The base {@link LayerCellPainter} that is decorated.
 	 */
-	private final ICellPainter baseCellPainter;
+	private final LayerCellPainter baseCellPainter;
 	/**
 	 * The edge of the cell at which the decoration is applied.
 	 */
 	private final CellEdgeEnum cellEdge;
 	/**
-	 * The {@link ICellPainter} that is used to render the decoration.
+	 * The {@link LayerCellPainter} that is used to render the decoration.
 	 */
-	private final ICellPainter decoratorCellPainter;
+	private final LayerCellPainter decoratorCellPainter;
 	/**
 	 * The spacing to use between base painter and decoration painter.
 	 * Note: If you want to add <b>padding</b> between the decoration and the cell border
@@ -64,36 +64,36 @@ public class CellPainterDecorator implements ICellPainter {
     /**
      * Will create a {@link CellPainterDecorator} with the default spacing of 2 between base and 
      * decoration painter, where the base painter is rendered dependent to the decoration.
-     * @param baseCellPainter The base {@link ICellPainter} that should be decorated
+     * @param baseCellPainter The base {@link LayerCellPainter} that should be decorated
      * @param cellEdge The edge of the cell at which the decoration should be applied
-     * @param decoratorCellPainter The {@link ICellPainter} that should be used to render the decoration.
+     * @param decoratorCellPainter The {@link LayerCellPainter} that should be used to render the decoration.
      */
-	public CellPainterDecorator(final ICellPainter baseCellPainter, final CellEdgeEnum cellEdge, final ICellPainter decoratorCellPainter) {
+	public CellPainterDecorator(final LayerCellPainter baseCellPainter, final CellEdgeEnum cellEdge, final LayerCellPainter decoratorCellPainter) {
 		this(baseCellPainter, cellEdge, 2, decoratorCellPainter);
 	}
 
     /**
      * Will create a {@link CellPainterDecorator} with the default spacing of 2 between base and 
      * decoration painter. If paintDecorationDependent is set to <code>false</code>, the spacing will be ignored.
-     * @param baseCellPainter The base {@link ICellPainter} that should be decorated
+     * @param baseCellPainter The base {@link LayerCellPainter} that should be decorated
      * @param cellEdge The edge of the cell at which the decoration should be applied
-     * @param decoratorCellPainter The {@link ICellPainter} that should be used to render the decoration.
+     * @param decoratorCellPainter The {@link LayerCellPainter} that should be used to render the decoration.
      * @param paintDecorationDependent Flag to specify whether the base painter should render dependent to the 
      * 			decoration painter or not.
      */
-	public CellPainterDecorator(final ICellPainter baseCellPainter, final CellEdgeEnum cellEdge, final ICellPainter decoratorCellPainter, final boolean paintDecorationDependent) {
+	public CellPainterDecorator(final LayerCellPainter baseCellPainter, final CellEdgeEnum cellEdge, final LayerCellPainter decoratorCellPainter, final boolean paintDecorationDependent) {
 		this(baseCellPainter, cellEdge, 2, decoratorCellPainter, paintDecorationDependent);
 	}
 	
     /**
      * Will create a {@link CellPainterDecorator} with the given amount of pixels as spacing between base and 
      * decoration painter, where the base painter is rendered dependent to the decoration.
-     * @param baseCellPainter The base {@link ICellPainter} that should be decorated
+     * @param baseCellPainter The base {@link LayerCellPainter} that should be decorated
      * @param cellEdge The edge of the cell at which the decoration should be applied
      * @param spacing The amount of pixels that should be used as spacing between decoration and base painter
-     * @param decoratorCellPainter The {@link ICellPainter} that should be used to render the decoration.
+     * @param decoratorCellPainter The {@link LayerCellPainter} that should be used to render the decoration.
      */
-	public CellPainterDecorator(final ICellPainter baseCellPainter, final CellEdgeEnum cellEdge, final long spacing, final ICellPainter decoratorCellPainter) {
+	public CellPainterDecorator(final LayerCellPainter baseCellPainter, final CellEdgeEnum cellEdge, final long spacing, final LayerCellPainter decoratorCellPainter) {
 		this(baseCellPainter, cellEdge, spacing, decoratorCellPainter, true);
 	}
 	
@@ -101,13 +101,13 @@ public class CellPainterDecorator implements ICellPainter {
      * Will create a {@link CellPainterDecorator} with the given amount of pixels as spacing between base and 
      * decoration painter. If paintDecorationDependent is set to <code>false</code>, the spacing will be ignored
      * while the decoration is mainly rendered over the base painter.
-     * @param baseCellPainter The base {@link ICellPainter} that should be decorated
+     * @param baseCellPainter The base {@link LayerCellPainter} that should be decorated
      * @param cellEdge The edge of the cell at which the decoration should be applied
-     * @param decoratorCellPainter The {@link ICellPainter} that should be used to render the decoration.
+     * @param decoratorCellPainter The {@link LayerCellPainter} that should be used to render the decoration.
      * @param paintDecorationDependent Flag to specify whether the base painter should render dependent to the 
      * 			decoration painter or not.
      */
-	public CellPainterDecorator(final ICellPainter baseCellPainter, final CellEdgeEnum cellEdge, final long spacing, final ICellPainter decoratorCellPainter, final boolean paintDecorationDependent) {
+	public CellPainterDecorator(final LayerCellPainter baseCellPainter, final CellEdgeEnum cellEdge, final long spacing, final LayerCellPainter decoratorCellPainter, final boolean paintDecorationDependent) {
 		this.baseCellPainter= baseCellPainter;
 		this.cellEdge= cellEdge;
 		this.spacing= spacing;
@@ -125,7 +125,7 @@ public class CellPainterDecorator implements ICellPainter {
 	}
 	
     @Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		switch (this.cellEdge) {
 		case TOP_LEFT:
 		case TOP_RIGHT:
@@ -148,7 +148,7 @@ public class CellPainterDecorator implements ICellPainter {
 	}
 
     @Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		switch (this.cellEdge) {
 		case TOP_LEFT:
 		case TOP_RIGHT:
@@ -171,13 +171,13 @@ public class CellPainterDecorator implements ICellPainter {
 	}
 
     @Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		final LRectangle baseCellPainterBounds= this.paintDecorationDependent ? 
 				getBaseCellPainterBounds(cell, gc, adjustedCellBounds, configRegistry) : adjustedCellBounds;
 		final LRectangle decoratorCellPainterBounds= getDecoratorCellPainterBounds(cell, gc, adjustedCellBounds, configRegistry);
 		
 		final Color originalBg= gc.getBackground();
-		gc.setBackground(CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR));
+		gc.setBackground(CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyling.BACKGROUND_COLOR));
 		
 		gc.fillRectangle(safe(adjustedCellBounds));
 		
@@ -191,7 +191,7 @@ public class CellPainterDecorator implements ICellPainter {
 	 * 
 	 * @return The LRectangle which can be used by the base cell painter. 
 	 */
-	public LRectangle getBaseCellPainterBounds(final ILayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public LRectangle getBaseCellPainterBounds(final LayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		final long preferredDecoratorWidth= this.decoratorCellPainter.getPreferredWidth(cell, gc, configRegistry);
 		final long preferredDecoratorHeight= this.decoratorCellPainter.getPreferredHeight(cell, gc, configRegistry);
 		
@@ -266,7 +266,7 @@ public class CellPainterDecorator implements ICellPainter {
 	/**
 	 * @return The LRectangle to paint the decoration.
 	 */
-	public LRectangle getDecoratorCellPainterBounds(final ILayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public LRectangle getDecoratorCellPainterBounds(final LayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		final long preferredDecoratorWidth= this.decoratorCellPainter.getPreferredWidth(cell, gc, configRegistry);
 		final long preferredDecoratorHeight= this.decoratorCellPainter.getPreferredHeight(cell, gc, configRegistry);
 		
@@ -327,7 +327,7 @@ public class CellPainterDecorator implements ICellPainter {
 	}
 	
 	@Override
-	public ICellPainter getCellPainterAt(final long x, final long y, final ILayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public LayerCellPainter getCellPainterAt(final long x, final long y, final LayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		final LRectangle decoratorCellPainterBounds= getDecoratorCellPainterBounds(cell, gc, adjustedCellBounds, configRegistry);
 		if (decoratorCellPainterBounds.contains(x, y)) {
 			return this.decoratorCellPainter.getCellPainterAt(x, y, cell, gc, decoratorCellPainterBounds, configRegistry);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/CustomLineBorderDecorator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/CustomLineBorderDecorator.java
deleted file mode 100644
index d586f173..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/CustomLineBorderDecorator.java
+++ /dev/null
@@ -1,250 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Dirk Fauth and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Dirk Fauth <dirk.fauth@gmail.com> - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.painter.cell.decorator;
-
-import java.util.List;
-
-import org.eclipse.swt.graphics.Color;
-import org.eclipse.swt.graphics.GC;
-import org.eclipse.swt.graphics.Point;
-
-import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.painter.cell.CellPainterWrapper;
-import org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
-
-
-/**
- * {@link NatTable} decorator class which is used to draw borders for cells whose LabelStack
- * contains border related labels.
- * <p>Compared to the LineBorderDecorator which paints a border for every side of a cell,
- * with this implementation you are free to choose for which side a border should be painted
- * or not.</p>
- */
-public class CustomLineBorderDecorator extends CellPainterWrapper {
-
-	/**
-	 * Label for adding a border at the top of a cell.
-	 */
-	public static final String TOP_LINE_BORDER_LABEL= "topLineBorderLabel"; //$NON-NLS-1$
-	/**
-	 * Label for adding a border at the bottom of a cell.
-	 */
-	public static final String BOTTOM_LINE_BORDER_LABEL= "bottomLineBorderLabel"; //$NON-NLS-1$
-	/**
-	 * Label for adding a border at the left of a cell.
-	 */
-	public static final String LEFT_LINE_BORDER_LABEL= "leftLineBorderLabel"; //$NON-NLS-1$
-	/**
-	 * Label for adding a border at the right of a cell.
-	 */
-	public static final String RIGHT_LINE_BORDER_LABEL= "rightLineBorderLabel"; //$NON-NLS-1$
-	
-	/**
-	 * The default border style which will be used if no border style is configured via
-	 * cell style configuration. Can be <code>null</code> if there should be no border
-	 * rendered by default.
-	 */
-	private final BorderStyle defaultBorderStyle;
-
-	/**
-	 * Creates a new LabelLineBorderDecorator wrapping the given interior painter and no
-	 * default border style.
-	 * @param interiorPainter The painter to be wrapped by this decorator.
-	 */
-	public CustomLineBorderDecorator(final ICellPainter interiorPainter) {
-		this(interiorPainter, null);
-	}
-	
-	/**
-	 * Creates a new LabelLineBorderDecorator wrapping the given interior painter using
-	 * the given BorderStyle as default.
-	 * @param interiorPainter The painter to be wrapped by this decorator.
-	 * @param defaultBorderStyle The BorderStyle to use as default if there is no BorderStyle
-	 * 			configured via cell styles. Can be <code>null</code>.
-	 */
-	public CustomLineBorderDecorator(final ICellPainter interiorPainter, final BorderStyle defaultBorderStyle) {
-		super(interiorPainter);
-		this.defaultBorderStyle= defaultBorderStyle;
-	}
-
-	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
-		final BorderStyle borderStyle= getBorderStyle(cell, configRegistry);
-		final long borderThickness= borderStyle != null ? borderStyle.getThickness() : 0;
-		
-		long borderLineCount= 0;
-		//check how many border lines are configured for that cell
-		final List<String> labels= cell.getConfigLabels().getLabels();
-		if (labels.contains(RIGHT_LINE_BORDER_LABEL)) {
-			borderLineCount++;
-		}
-		if (labels.contains(LEFT_LINE_BORDER_LABEL)) {
-			borderLineCount++;
-		}
-		
-		return super.getPreferredWidth(cell, gc, configRegistry) + (borderThickness * borderLineCount);
-	}
-	
-	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
-		final BorderStyle borderStyle= getBorderStyle(cell, configRegistry);
-		final long borderThickness= borderStyle != null ? borderStyle.getThickness() : 0;
-		
-		long borderLineCount= 0;
-		//check how many border lines are configured for that cell
-		final List<String> labels= cell.getConfigLabels().getLabels();
-		if (labels.contains(TOP_LINE_BORDER_LABEL)) {
-			borderLineCount++;
-		}
-		if (labels.contains(BOTTOM_LINE_BORDER_LABEL)) {
-			borderLineCount++;
-		}
-		
-		return super.getPreferredHeight(cell, gc, configRegistry) + (borderThickness * borderLineCount);
-	}
-
-	private BorderStyle getBorderStyle(final ILayerCell cell, final IConfigRegistry configRegistry) {
-		final IStyle cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
-		BorderStyle borderStyle= cellStyle.getAttributeValue(CellStyleAttributes.BORDER_STYLE);
-		if (borderStyle == null) {
-			borderStyle= this.defaultBorderStyle;
-		}
-		return borderStyle;
-	}
-
-	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle lRectangle, final IConfigRegistry configRegistry) {
-		final BorderStyle borderStyle= getBorderStyle(cell, configRegistry);
-		final int borderThickness= borderStyle != null ? borderStyle.getThickness() : 0;
-		
-		//check how many border lines are configured for that cell
-		final List<String> labels= cell.getConfigLabels().getLabels();
-
-		long leftBorderThickness= 0;
-		long rightBorderThickness= 0;
-		long topBorderThickness= 0;
-		long bottomBorderThickness= 0;
-		
-		if (labels.contains(LEFT_LINE_BORDER_LABEL)) {
-			leftBorderThickness= borderThickness;
-		}
-		if (labels.contains(RIGHT_LINE_BORDER_LABEL)) {
-			rightBorderThickness= borderThickness;
-		}
-		if (labels.contains(TOP_LINE_BORDER_LABEL)) {
-			topBorderThickness= borderThickness;
-		}
-		if (labels.contains(BOTTOM_LINE_BORDER_LABEL)) {
-			bottomBorderThickness= borderThickness;
-		}
-
-		final LRectangle interiorBounds =
-			new LRectangle(
-					lRectangle.x + leftBorderThickness,
-					lRectangle.y + topBorderThickness,
-					(lRectangle.width - leftBorderThickness - rightBorderThickness),
-					(lRectangle.height - topBorderThickness - bottomBorderThickness)
-			);
-		super.paintCell(cell, gc, interiorBounds, configRegistry);
-		
-		if (borderStyle == null || borderThickness <= 0 || 
-				(leftBorderThickness == 0 && rightBorderThickness == 0 
-						&& topBorderThickness == 0 && bottomBorderThickness == 0)) {
-			return;
-		}
-		
-		// Save GC settings
-		final Color originalForeground= gc.getForeground();
-		final int originalLineWidth= gc.getLineWidth();
-		final int originalLineStyle= gc.getLineStyle();
-
-		gc.setLineWidth(borderThickness);
-
-		final LRectangle borderArea= new LRectangle(lRectangle.x, lRectangle.y, lRectangle.width, lRectangle.height);
-		if (borderThickness >= 1) {
-			int shift= 0;
-			int correction= 0;
-
-			if ((borderThickness % 2) == 0) {
-				shift= borderThickness / 2;
-			} else {
-				shift= borderThickness / 2;
-				correction= 1;
-			}
-
-			if (leftBorderThickness >= 1) {
-				borderArea.x+= shift;
-				borderArea.width-= shift;
-			}
-			
-			if (rightBorderThickness >= 1) {
-				borderArea.width-= shift + correction;
-			}
-			
-			if (topBorderThickness >= 1) {
-				borderArea.y+= shift;
-				borderArea.height-= shift;
-			}
-			
-			if (bottomBorderThickness >= 1) {
-				borderArea.height-= shift + correction;
-			}
-		}
-
-		gc.setLineStyle(SWTUtil.toSWT(borderStyle.getLineStyle()));
-		gc.setForeground(borderStyle.getColor());
-		
-		final org.eclipse.swt.graphics.Rectangle rect= GraphicsUtils.safe(borderArea);
-		//if all borders are set draw a rectangle
-		if (leftBorderThickness > 0 && rightBorderThickness > 0 
-						&& topBorderThickness > 0 && bottomBorderThickness > 0) {
-			gc.drawRectangle(rect);
-		}
-		//else draw a line for every set border
-		else {
-			final Point topLeftPos= new Point(rect.x, rect.y); 
-			final Point topRightPos= new Point(rect.x + rect.width, rect.y); 
-			final Point bottomLeftPos= new Point(rect.x, rect.y + rect.height); 
-			final Point bottomRightPos= new Point(rect.x + rect.width, rect.y + rect.height); 
-			
-			if (leftBorderThickness > 0) {
-				gc.drawLine(topLeftPos.x, topLeftPos.y, bottomLeftPos.x, bottomLeftPos.y);
-			}
-			if (rightBorderThickness > 0) {
-				gc.drawLine(topRightPos.x, topRightPos.y, bottomRightPos.x, bottomRightPos.y);
-			}
-			if (topBorderThickness > 0) {
-				gc.drawLine(topLeftPos.x, topLeftPos.y, topRightPos.x, topRightPos.y);
-			}
-			if (bottomBorderThickness > 0) {
-				gc.drawLine(bottomLeftPos.x, bottomLeftPos.y, bottomRightPos.x, bottomRightPos.y);
-			}
-		}
-
-		// Restore GC settings
-		gc.setForeground(originalForeground);
-		gc.setLineWidth(originalLineWidth);
-		gc.setLineStyle(originalLineStyle);
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/LineBorderDecorator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/LineBorderDecorator.java
index acdeb7cd..c76b620e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/LineBorderDecorator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/LineBorderDecorator.java
@@ -16,35 +16,35 @@ package org.eclipse.statet.ecommons.waltable.painter.cell.decorator;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
 import org.eclipse.statet.ecommons.waltable.painter.cell.CellPainterWrapper;
 import org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
 
 
 public class LineBorderDecorator extends CellPainterWrapper {
 
 	private final BorderStyle defaultBorderStyle;
 
-	public LineBorderDecorator(final ICellPainter interiorPainter) {
+	public LineBorderDecorator(final LayerCellPainter interiorPainter) {
 		this(interiorPainter, null);
 	}
 	
-	public LineBorderDecorator(final ICellPainter interiorPainter, final BorderStyle defaultBorderStyle) {
+	public LineBorderDecorator(final LayerCellPainter interiorPainter, final BorderStyle defaultBorderStyle) {
 		super(interiorPainter);
 		this.defaultBorderStyle= defaultBorderStyle;
 	}
 
 
 	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		final BorderStyle borderStyle= getBorderStyle(cell, configRegistry);
 		final long padding= borderStyle != null ? Math.max(borderStyle.getOffset() + borderStyle.getThickness(), 0) : 0;
 		
@@ -52,16 +52,16 @@ public class LineBorderDecorator extends CellPainterWrapper {
 	}
 	
 	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		final BorderStyle borderStyle= getBorderStyle(cell, configRegistry);
 		final long padding= borderStyle != null ? Math.max(borderStyle.getOffset() + borderStyle.getThickness(), 0) : 0;
 		
 		return super.getPreferredHeight(cell, gc, configRegistry) + (padding * 2);
 	}
 
-	private BorderStyle getBorderStyle(final ILayerCell cell, final IConfigRegistry configRegistry) {
-		final IStyle cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
-		BorderStyle borderStyle= cellStyle.getAttributeValue(CellStyleAttributes.BORDER_STYLE);
+	private BorderStyle getBorderStyle(final LayerCell cell, final ConfigRegistry configRegistry) {
+		final Style cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
+		BorderStyle borderStyle= cellStyle.getAttributeValue(CellStyling.BORDER_STYLE);
 		if (borderStyle == null) {
 			borderStyle= this.defaultBorderStyle;
 		}
@@ -69,7 +69,7 @@ public class LineBorderDecorator extends CellPainterWrapper {
 	}
 
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle lRectangle, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle lRectangle, final ConfigRegistry configRegistry) {
 		final BorderStyle borderStyle= getBorderStyle(cell, configRegistry);
 		
 		final long padding= borderStyle != null ? Math.max(borderStyle.getOffset() + borderStyle.getThickness(), 0) : 0;
@@ -93,14 +93,8 @@ public class LineBorderDecorator extends CellPainterWrapper {
 		
 		final long borderOffset= borderStyle.getOffset();
 		final int borderThickness= borderStyle.getThickness();
-		final LRectangle borderArea= new LRectangle(
-						lRectangle.x + borderOffset,
-						lRectangle.y + borderOffset,
-						lRectangle.width - (borderOffset * 2),
-						lRectangle.height - (borderOffset * 2)
-				);
-		{
-			long shift= 0;
+		final LRectangle borderArea;
+		{	long shift= 0;
 			long areaShift= 0;
 			if ((borderThickness % 2) == 0) {
 				shift= borderThickness / 2;
@@ -109,14 +103,15 @@ public class LineBorderDecorator extends CellPainterWrapper {
 				shift= borderThickness / 2;
 				areaShift= (shift * 2) + 1;
 			}
-			borderArea.x+= shift;
-			borderArea.y+= shift;
-			borderArea.width-= areaShift;
-			borderArea.height-= areaShift;
+			borderArea= new LRectangle(
+						lRectangle.x + borderOffset + shift,
+						lRectangle.y + borderOffset + shift,
+						lRectangle.width - (borderOffset * 2) - areaShift,
+						lRectangle.height - (borderOffset * 2) - areaShift );
 		}
-
+		
 		gc.setLineWidth(borderThickness);
-		gc.setLineStyle(SWTUtil.toSWT(borderStyle.getLineStyle()));
+		gc.setLineStyle(SwtUtils.toSWT(borderStyle.getLineStyle()));
 		gc.setForeground(borderStyle.getColor());
 		gc.drawRectangle(GraphicsUtils.safe(borderArea));
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/PaddingDecorator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/PaddingDecorator.java
index f931c99a..450a7472 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/PaddingDecorator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/PaddingDecorator.java
@@ -18,16 +18,16 @@ import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.sa
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.style.VerticalAlignment;
 import org.eclipse.statet.ecommons.waltable.painter.cell.CellPainterWrapper;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
-import org.eclipse.statet.ecommons.waltable.style.VerticalAlignment;
 
 
 public class PaddingDecorator extends CellPainterWrapper {
@@ -39,15 +39,15 @@ public class PaddingDecorator extends CellPainterWrapper {
 	private final long leftPadding;
 	
 	
-	public PaddingDecorator(final ICellPainter interiorPainter) {
+	public PaddingDecorator(final LayerCellPainter interiorPainter) {
 		this(interiorPainter, 2);
 	}
 	
-	public PaddingDecorator(final ICellPainter interiorPainter, final long padding) {
+	public PaddingDecorator(final LayerCellPainter interiorPainter, final long padding) {
 		this(interiorPainter, padding, padding, padding, padding);
 	}
 	
-	public PaddingDecorator(final ICellPainter interiorPainter, final long topPadding, final long rightPadding, final long bottomPadding, final long leftPadding) {
+	public PaddingDecorator(final LayerCellPainter interiorPainter, final long topPadding, final long rightPadding, final long bottomPadding, final long leftPadding) {
 		super(interiorPainter);
 		this.topPadding= topPadding;
 		this.rightPadding= rightPadding;
@@ -57,17 +57,17 @@ public class PaddingDecorator extends CellPainterWrapper {
 	
 	
 	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return this.leftPadding + super.getPreferredWidth(cell, gc, configRegistry) + this.rightPadding;
 	}
 	
 	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return this.topPadding + super.getPreferredHeight(cell, gc, configRegistry) + this.bottomPadding;
 	}
 	
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		final Color originalBg= gc.getBackground();
 		final Color cellStyleBackground= getBackgroundColor(cell, configRegistry);
 		if (cellStyleBackground != null) {
@@ -94,16 +94,16 @@ public class PaddingDecorator extends CellPainterWrapper {
 		);
 	}
 	
-	protected Color getBackgroundColor(final ILayerCell cell, final IConfigRegistry configRegistry) {
-		return CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);		
+	protected Color getBackgroundColor(final LayerCell cell, final ConfigRegistry configRegistry) {
+		return CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(CellStyling.BACKGROUND_COLOR);		
 	}
 	
 	@Override
-	public ICellPainter getCellPainterAt(final long x, final long y, final ILayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final IConfigRegistry configRegistry) {
+	public LayerCellPainter getCellPainterAt(final long x, final long y, final LayerCell cell, final GC gc, final LRectangle adjustedCellBounds, final ConfigRegistry configRegistry) {
 		//need to take the alignment into account
-		final IStyle cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
+		final Style cellStyle= CellStyleUtil.getCellStyle(cell, configRegistry);
 		
-		final HorizontalAlignment horizontalAlignment= cellStyle.getAttributeValue(CellStyleAttributes.HORIZONTAL_ALIGNMENT);
+		final HorizontalAlignment horizontalAlignment= cellStyle.getAttributeValue(CellStyling.HORIZONTAL_ALIGNMENT);
 		long horizontalAlignmentPadding= 0;
 		switch (horizontalAlignment) {
 			case LEFT: horizontalAlignmentPadding= this.leftPadding;
@@ -112,7 +112,7 @@ public class PaddingDecorator extends CellPainterWrapper {
 						break;
 		}
 		
-		final VerticalAlignment verticalAlignment= cellStyle.getAttributeValue(CellStyleAttributes.VERTICAL_ALIGNMENT);
+		final VerticalAlignment verticalAlignment= cellStyle.getAttributeValue(CellStyling.VERTICAL_ALIGNMENT);
 		long verticalAlignmentPadding= 0;
 		switch (verticalAlignment) {
 			case TOP: verticalAlignmentPadding= this.topPadding;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/PercentageBarDecorator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/PercentageBarDecorator.java
index 0b0e6912..7240af49 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/PercentageBarDecorator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/PercentageBarDecorator.java
@@ -19,17 +19,17 @@ import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Pattern;
 import org.eclipse.swt.graphics.RGB;
+import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.graphics.Region;
 import org.eclipse.swt.widgets.Display;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.CellPainterWrapper;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
 /**
@@ -41,22 +41,22 @@ public class PercentageBarDecorator extends CellPainterWrapper {
 	public static final ConfigAttribute<Color> PERCENTAGE_BAR_COMPLETE_REGION_END_COLOR= new ConfigAttribute<>();
 	public static final ConfigAttribute<Color> PERCENTAGE_BAR_INCOMPLETE_REGION_COLOR= new ConfigAttribute<>();
 	
-	private static final Color DEFAULT_COMPLETE_REGION_START_COLOR= GUIHelper.getColor(new RGB(187, 216, 254));
-	private static final Color DEFAULT_COMPLETE_REGION_END_COLOR= GUIHelper.getColor(new RGB(255, 255, 255));
+	private static final Color DEFAULT_COMPLETE_REGION_START_COLOR= new Color(new RGB(187, 216, 254));
+	private static final Color DEFAULT_COMPLETE_REGION_END_COLOR= new Color(new RGB(255, 255, 255));
 	
-	public PercentageBarDecorator(final ICellPainter interiorPainter) {
+	public PercentageBarDecorator(final LayerCellPainter interiorPainter) {
 		super(interiorPainter);
 	}
 
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle lRectangle, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle lRectangle, final ConfigRegistry configRegistry) {
 		final Pattern originalBackgroundPattern= gc.getBackgroundPattern();
 
 		double factor= Math.min(1.0, ((Double) cell.getDataValue(0, null)).doubleValue());
 		factor= Math.max(0.0, factor);
 
 		final LRectangle bar= new LRectangle(lRectangle.x, lRectangle.y, (long) (lRectangle.width * factor), lRectangle.height);
-		final org.eclipse.swt.graphics.Rectangle rect= safe(bar);
+		final Rectangle rect= safe(bar);
 		final LRectangle bounds= cell.getBounds();
 		
 		Color color1= CellStyleUtil.getCellStyle(cell, configRegistry).getAttributeValue(PERCENTAGE_BAR_COMPLETE_REGION_START_COLOR);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/XPBackgroundDecorator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/XPBackgroundDecorator.java
index bea7648f..e0e8b5c3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/XPBackgroundDecorator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/painter/cell/decorator/XPBackgroundDecorator.java
@@ -18,11 +18,11 @@ import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.sa
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.BackgroundPainter;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -38,32 +38,32 @@ public class XPBackgroundDecorator extends BackgroundPainter {
 	public final Color highlightColor2;
 	public final Color highlightColor3;
 
-	public XPBackgroundDecorator(final ICellPainter interiorPainter) {
+	public XPBackgroundDecorator(final LayerCellPainter interiorPainter) {
 		super(interiorPainter);
 		
-		this.separatorColor= GUIHelper.getColor(199, 197, 178);
+		this.separatorColor= new Color(199, 197, 178);
 		
-		this.gradientColor1= GUIHelper.getColor(226, 222, 205);
-		this.gradientColor2= GUIHelper.getColor(214, 210, 194);
-		this.gradientColor3= GUIHelper.getColor(203, 199, 184);
+		this.gradientColor1= new Color(226, 222, 205);
+		this.gradientColor2= new Color(214, 210, 194);
+		this.gradientColor3= new Color(203, 199, 184);
 		
-		this.highlightColor1= GUIHelper.getColor(250, 171, 0);
-		this.highlightColor2= GUIHelper.getColor(252, 194, 71);
-		this.highlightColor3= GUIHelper.getColor(250, 178, 24);
+		this.highlightColor1= new Color(250, 171, 0);
+		this.highlightColor2= new Color(252, 194, 71);
+		this.highlightColor3= new Color(250, 178, 24);
 	}
 
 	@Override
-	public long getPreferredWidth(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredWidth(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return super.getPreferredWidth(cell, gc, configRegistry) + 4;
 	}
 	
 	@Override
-	public long getPreferredHeight(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	public long getPreferredHeight(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		return super.getPreferredHeight(cell, gc, configRegistry) + 4;
 	}
 
 	@Override
-	public void paintCell(final ILayerCell cell, final GC gc, final LRectangle lRectangle, final IConfigRegistry configRegistry) {
+	public void paintCell(final LayerCell cell, final GC gc, final LRectangle lRectangle, final ConfigRegistry configRegistry) {
 		// Draw background
 		super.paintCell(cell, gc, lRectangle, configRegistry);
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/ColorPersistor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/ColorPersistor.java
index 43152b78..eb748ba6 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/ColorPersistor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/ColorPersistor.java
@@ -13,9 +13,9 @@
 
 package org.eclipse.statet.ecommons.waltable.persistence;
 
-import static org.eclipse.statet.ecommons.waltable.persistence.IPersistable.DOT;
+import static org.eclipse.statet.ecommons.waltable.core.Persistable.DOT;
 
-import java.util.Properties;
+import java.util.Map;
 
 import org.eclipse.jface.resource.DataFormatException;
 import org.eclipse.jface.resource.StringConverter;
@@ -23,28 +23,26 @@ import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.widgets.Display;
 
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
-
 
 public class ColorPersistor {
 
 	public static final String STYLE_PERSISTENCE_PREFIX= "color"; //$NON-NLS-1$
 	public static final Color DEFAULT_COLOR= Display.getDefault().getSystemColor(SWT.COLOR_WHITE);
 
-	public static void saveColor(String prefix, final Properties properties, final Color color) {
+	public static void saveColor(String prefix, final Map<String, String> properties, final Color color) {
 		prefix= prefix + DOT + STYLE_PERSISTENCE_PREFIX;
 
 		if (color == null) {
 			return;
 		}
-		properties.setProperty(prefix, asString(color));
+		properties.put(prefix, asString(color));
 	}
 
 
-	public static Color loadColor(String prefix, final Properties properties) {
+	public static Color loadColor(String prefix, final Map<String, String> properties) {
 		prefix= prefix + DOT + STYLE_PERSISTENCE_PREFIX;
 
-		final String colorAsString= properties.getProperty(prefix);
+		final String colorAsString= properties.get(prefix);
 		if (colorAsString == null) {
 			return null;
 		} else {
@@ -64,7 +62,7 @@ public class ColorPersistor {
 	 */
 	public static Color asColor(final String colorAsString) {
 		try {
-			return GUIHelper.getColor(StringConverter.asRGB(colorAsString));
+			return new Color(StringConverter.asRGB(colorAsString));
 		} catch (final DataFormatException e) {
 			return DEFAULT_COLOR;
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/DisplayPersistenceDialogCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/DisplayPersistenceDialogCommand.java
index d2b717e3..d2c3d0e2 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/DisplayPersistenceDialogCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/DisplayPersistenceDialogCommand.java
@@ -14,7 +14,7 @@
 package org.eclipse.statet.ecommons.waltable.persistence;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
 
 public class DisplayPersistenceDialogCommand extends AbstractContextFreeCommand {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/DisplayPersistenceDialogCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/DisplayPersistenceDialogCommandHandler.java
index a60c8cd7..a650d264 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/DisplayPersistenceDialogCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/DisplayPersistenceDialogCommandHandler.java
@@ -15,10 +15,11 @@ package org.eclipse.statet.ecommons.waltable.persistence;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 import java.util.Properties;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
 import org.eclipse.statet.ecommons.waltable.persistence.gui.PersistenceDialog;
 
 
@@ -33,7 +34,7 @@ public class DisplayPersistenceDialogCommandHandler extends AbstractLayerCommand
 	/**
 	 * The Properties instance that should be used for saving and loading.
 	 */
-	private Properties properties;
+	private Map<String, String> properties;
 	
 	/**
 	 * List of {@link IStateChangedListener}s that will be notified if states are changed
@@ -52,7 +53,7 @@ public class DisplayPersistenceDialogCommandHandler extends AbstractLayerCommand
 	 * It can be accessed via getProperties() for further usage.
 	 */
 	public DisplayPersistenceDialogCommandHandler() {
-		this(new Properties(), null);
+		this((Map)new Properties(), null);
 	}
 
 	/**
@@ -66,7 +67,7 @@ public class DisplayPersistenceDialogCommandHandler extends AbstractLayerCommand
 	 * 			in the opened dialog.
 	 */
 	public DisplayPersistenceDialogCommandHandler(final NatTable natTable) {
-		this(new Properties(), natTable);
+		this((Map)new Properties(), natTable);
 	}
 
 	/**
@@ -74,7 +75,7 @@ public class DisplayPersistenceDialogCommandHandler extends AbstractLayerCommand
 	 * instance.
 	 * @param properties The Properties instance that should be used for saving and loading.
 	 */
-	public DisplayPersistenceDialogCommandHandler(final Properties properties) {
+	public DisplayPersistenceDialogCommandHandler(final Map<String, String> properties) {
 		this(properties, null);
 	}
 
@@ -88,7 +89,7 @@ public class DisplayPersistenceDialogCommandHandler extends AbstractLayerCommand
 	 * 			default configuration. This default configuration can't be modified anymore
 	 * 			in the opened dialog.
 	 */
-	public DisplayPersistenceDialogCommandHandler(final Properties properties, final NatTable natTable) {
+	public DisplayPersistenceDialogCommandHandler(final Map<String, String> properties, final NatTable natTable) {
 		if (properties == null) {
 			throw new IllegalArgumentException("properties can not be null!"); //$NON-NLS-1$
 		}
@@ -96,7 +97,7 @@ public class DisplayPersistenceDialogCommandHandler extends AbstractLayerCommand
 		
 		if (natTable != null) {
 			natTable.saveState("", this.properties); //$NON-NLS-1$
-			this.properties.setProperty(PersistenceDialog.ACTIVE_VIEW_CONFIGURATION_KEY, ""); //$NON-NLS-1$
+			this.properties.put(PersistenceDialog.ACTIVE_VIEW_CONFIGURATION_KEY, ""); //$NON-NLS-1$
 		}
 	}
 	
@@ -117,14 +118,14 @@ public class DisplayPersistenceDialogCommandHandler extends AbstractLayerCommand
 	/**
 	 * @return The Properties instance that is used for saving and loading.
 	 */
-	public Properties getProperties() {
+	public Map<String, String> getProperties() {
 		return this.properties;
 	}
 
 	/**
 	 * @param properties The Properties instance that should be used for saving and loading.
 	 */
-	public void setProperties(final Properties properties) {
+	public void setProperties(final Map<String, String> properties) {
 		if (properties == null) {
 			throw new IllegalArgumentException("properties can not be null!"); //$NON-NLS-1$
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/PersistenceHelper.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/PersistenceHelper.java
index 662018bc..acb94c05 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/PersistenceHelper.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/PersistenceHelper.java
@@ -17,9 +17,10 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.List;
-import java.util.Properties;
+import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
 import org.eclipse.statet.ecommons.waltable.persistence.gui.PersistenceDialog;
 
 
@@ -36,13 +37,13 @@ public class PersistenceHelper {
 	 * 				Can be interpreted as state configuration name.
 	 * @param properties The properties containing the state configuration.
 	 */
-	public static void deleteState(final String prefix, final Properties properties) {
+	public static void deleteState(final String prefix, final Map<String, String> properties) {
 		if (properties != null) {
 			//build the key prefix to search for
 			//always add the dot as states without a prefix are stored with a leading dot
 			//and for named states it might be possible that there are some starting with
 			//the same prefix, so the dot clarifies the prefix
-			final String keyPrefix= prefix + IPersistable.DOT;
+			final String keyPrefix= prefix + Persistable.DOT;
 			
 			//collect the keys to remove
 			final List<Object> keysToRemove= new ArrayList<>();
@@ -67,7 +68,7 @@ public class PersistenceHelper {
 	 * @param properties The Properties to retrieve the containing states of
 	 * @return Collection of all state prefixes that are contained in the given properties.
 	 */
-	public static Collection<String> getAvailableStates(final Properties properties) {
+	public static Collection<String> getAvailableStates(final Map<String, String> properties) {
 		final Set<String> stateNames= new HashSet<>();
 		if (properties != null && !properties.isEmpty()) {
 			for (final Object key : properties.keySet()) {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/StylePersistor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/StylePersistor.java
index 85397841..55cbc876 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/StylePersistor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/StylePersistor.java
@@ -13,25 +13,26 @@
 
 package org.eclipse.statet.ecommons.waltable.persistence;
 
-import static org.eclipse.statet.ecommons.waltable.persistence.IPersistable.DOT;
-import static org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes.BACKGROUND_COLOR;
-import static org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes.BORDER_STYLE;
-import static org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes.FONT;
-import static org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes.FOREGROUND_COLOR;
-import static org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes.HORIZONTAL_ALIGNMENT;
-import static org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes.VERTICAL_ALIGNMENT;
+import static org.eclipse.statet.ecommons.waltable.core.Persistable.DOT;
+import static org.eclipse.statet.ecommons.waltable.core.style.CellStyling.BACKGROUND_COLOR;
+import static org.eclipse.statet.ecommons.waltable.core.style.CellStyling.BORDER_STYLE;
+import static org.eclipse.statet.ecommons.waltable.core.style.CellStyling.FONT;
+import static org.eclipse.statet.ecommons.waltable.core.style.CellStyling.FOREGROUND_COLOR;
+import static org.eclipse.statet.ecommons.waltable.core.style.CellStyling.HORIZONTAL_ALIGNMENT;
+import static org.eclipse.statet.ecommons.waltable.core.style.CellStyling.VERTICAL_ALIGNMENT;
 
-import java.util.Properties;
+import java.util.Map;
 
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.graphics.FontData;
 
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
-import org.eclipse.statet.ecommons.waltable.style.Style;
-import org.eclipse.statet.ecommons.waltable.style.VerticalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.style.VerticalAlignment;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -60,7 +61,7 @@ public class StylePersistor {
 
 	// Save
 
-	public static void saveStyle(String prefix, final Properties properties, final Style style) {
+	public static void saveStyle(String prefix, final Map<String, String> properties, final Style style) {
 		prefix= prefix + DOT + STYLE_PERSISTENCE_PREFIX;
 
 		saveColor(prefix + DOT + BG_COLOR_PREFIX, properties, style.getAttributeValue(BACKGROUND_COLOR));
@@ -74,35 +75,35 @@ public class StylePersistor {
 		saveBorder(prefix, properties, style.getAttributeValue(BORDER_STYLE));
 	}
 
-	protected static void saveVAlign(final String prefix, final Properties properties, final VerticalAlignment vAlign) {
+	protected static void saveVAlign(final String prefix, final Map<String, String> properties, final VerticalAlignment vAlign) {
 		if (vAlign == null) {
 			return;
 		}
-		properties.setProperty(prefix + DOT + V_ALIGNMENT_PREFIX, vAlign.name());
+		properties.put(prefix + DOT + V_ALIGNMENT_PREFIX, vAlign.name());
 	}
 
-	protected static void saveHAlign(final String prefix, final Properties properties, final HorizontalAlignment hAlign) {
+	protected static void saveHAlign(final String prefix, final Map<String, String> properties, final HorizontalAlignment hAlign) {
 		if (hAlign == null) {
 			return;
 		}
-		properties.setProperty(prefix + DOT + H_ALIGNMENT_PREFIX, hAlign.name());
+		properties.put(prefix + DOT + H_ALIGNMENT_PREFIX, hAlign.name());
 	}
 
-	protected static void saveBorder(final String prefix, final Properties properties, final BorderStyle borderStyle) {
+	protected static void saveBorder(final String prefix, final Map<String, String> properties, final BorderStyle borderStyle) {
 		if (borderStyle == null) {
 			return;
 		}
-		properties.setProperty(prefix + DOT + BORDER_PREFIX, String.valueOf(borderStyle.toString()));
+		properties.put(prefix + DOT + BORDER_PREFIX, String.valueOf(borderStyle.toString()));
 	}
 
-	protected static void saveFont(final String prefix, final Properties properties, final Font font) {
+	protected static void saveFont(final String prefix, final Map<String, String> properties, final Font font) {
 		if (font == null) {
 			return;
 		}
-		properties.setProperty(prefix + DOT + FONT_PREFIX, String.valueOf(font.getFontData()[0].toString()));
+		properties.put(prefix + DOT + FONT_PREFIX, String.valueOf(font.getFontData()[0].toString()));
 	}
 
-	protected static void saveColor(final String prefix, final Properties properties, final Color color) {
+	protected static void saveColor(final String prefix, final Map<String, String> properties, final Color color) {
 		if (color == null) {
 			return;
 		}
@@ -111,87 +112,87 @@ public class StylePersistor {
 
 	// Load
 
-	public static Style loadStyle(String prefix, final Properties properties) {
-		final Style style= new Style();
+	public static BasicStyle loadStyle(String prefix, final Map<String, String> properties) {
+		final var style= new BasicStyle();
 		prefix= prefix + DOT + STYLE_PERSISTENCE_PREFIX;
 
 		// BG Color
 		final String bgColorPrefix= prefix + DOT + BG_COLOR_PREFIX;
 		final Color bgColor= loadColor(bgColorPrefix, properties);
 		if (bgColor != null) {
-			style.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR, bgColor);
+			style.setAttributeValue(CellStyling.BACKGROUND_COLOR, bgColor);
 		}
 
 		// FG Color
 		final String fgColorPrefix= prefix + DOT + FG_COLOR_PREFIX;
 		final Color fgColor= loadColor(fgColorPrefix, properties);
 		if (fgColor != null) {
-			style.setAttributeValue(CellStyleAttributes.FOREGROUND_COLOR, fgColor);
+			style.setAttributeValue(CellStyling.FOREGROUND_COLOR, fgColor);
 		}
 
 		// Alignment
 		final String hAlignPrefix= prefix + DOT + H_ALIGNMENT_PREFIX;
 		final HorizontalAlignment hAlign= loadHAlignment(hAlignPrefix, properties);
 		if (hAlign != null) {
-			style.setAttributeValue(CellStyleAttributes.HORIZONTAL_ALIGNMENT, hAlign);
+			style.setAttributeValue(CellStyling.HORIZONTAL_ALIGNMENT, hAlign);
 		}
 
 		final String vAlignPrefix= prefix + DOT + V_ALIGNMENT_PREFIX;
 		final VerticalAlignment vAlign= loadVAlignment(vAlignPrefix, properties);
 		if (vAlign != null) {
-			style.setAttributeValue(CellStyleAttributes.VERTICAL_ALIGNMENT, vAlign);
+			style.setAttributeValue(CellStyling.VERTICAL_ALIGNMENT, vAlign);
 		}
 
 		// Font
 		final String fontPrefix= prefix + DOT + FONT_PREFIX;
 		final Font font= loadFont(fontPrefix, properties);
 		if (font != null) {
-			style.setAttributeValue(CellStyleAttributes.FONT, font);
+			style.setAttributeValue(CellStyling.FONT, font);
 		}
 
 		// Border Style
 		final String borderPrefix= prefix + DOT + BORDER_PREFIX;
 		final BorderStyle borderStyle= loadBorderStyle(borderPrefix, properties);
 		if (borderStyle != null) {
-			style.setAttributeValue(CellStyleAttributes.BORDER_STYLE, borderStyle);
+			style.setAttributeValue(CellStyling.BORDER_STYLE, borderStyle);
 		}
 
 		return style;
 	}
 
-	private static BorderStyle loadBorderStyle(final String borderPrefix, final Properties properties) {
-		final String borderStyle= properties.getProperty(borderPrefix);
+	private static BorderStyle loadBorderStyle(final String borderPrefix, final Map<String, String> properties) {
+		final String borderStyle= properties.get(borderPrefix);
 		if (borderStyle != null) {
 			return new BorderStyle(borderStyle);
 		}
 		return null;
 	}
 
-	private static Font loadFont(final String fontPrefix, final Properties properties) {
-		final String fontdata= properties.getProperty(fontPrefix);
+	private static Font loadFont(final String fontPrefix, final Map<String, String> properties) {
+		final String fontdata= properties.get(fontPrefix);
 		if (fontdata != null) {
 			return GUIHelper.getFont(new FontData(fontdata));
 		}
 		return null;
 	}
 
-	private static HorizontalAlignment loadHAlignment(final String hAlignPrefix, final Properties properties) {
-		final String enumName= properties.getProperty(hAlignPrefix);
+	private static HorizontalAlignment loadHAlignment(final String hAlignPrefix, final Map<String, String> properties) {
+		final String enumName= properties.get(hAlignPrefix);
 		if (enumName != null) {
 			return HorizontalAlignment.valueOf(enumName);
 		}
 		return null;
 	}
 
-	private static VerticalAlignment loadVAlignment(final String vAlignPrefix, final Properties properties) {
-		final String enumName= properties.getProperty(vAlignPrefix);
+	private static VerticalAlignment loadVAlignment(final String vAlignPrefix, final Map<String, String> properties) {
+		final String enumName= properties.get(vAlignPrefix);
 		if (enumName != null) {
 			return VerticalAlignment.valueOf(enumName);
 		}
 		return null;
 	}
 
-	protected static Color loadColor(final String prefix, final Properties properties) {
+	protected static Color loadColor(final String prefix, final Map<String, String> properties) {
 		return ColorPersistor.loadColor(prefix, properties);
 	}
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/gui/PersistenceDialog.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/gui/PersistenceDialog.java
index e0084dd4..0770bbdf 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/gui/PersistenceDialog.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/gui/PersistenceDialog.java
@@ -15,7 +15,7 @@ package org.eclipse.statet.ecommons.waltable.persistence.gui;
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Properties;
+import java.util.Map;
 
 import org.eclipse.jface.dialogs.Dialog;
 import org.eclipse.jface.dialogs.IDialogConstants;
@@ -109,7 +109,7 @@ public class PersistenceDialog extends Dialog {
 	/**
 	 * The Properties instance that should be used for saving and loading.
 	 */
-	private Properties properties;
+	private Map<String, String> properties;
 	
 	/**
 	 * Viewer containing the state configurations.
@@ -142,7 +142,7 @@ public class PersistenceDialog extends Dialog {
 	 * @param natTable The NatTable instance to apply the save/load operations.
 	 * @param properties The Properties instance that should be used for saving and loading.
 	 */
-	public PersistenceDialog(final Shell parentShell, final NatTable natTable, final Properties properties) {
+	public PersistenceDialog(final Shell parentShell, final NatTable natTable, final Map<String, String> properties) {
 		super(parentShell);
 		setShellStyle(SWT.RESIZE | SWT.APPLICATION_MODAL| SWT.DIALOG_TRIM);
 		
@@ -336,14 +336,14 @@ public class PersistenceDialog extends Dialog {
 	/**
 	 * @return The Properties instance that is used for saving and loading.
 	 */
-	public Properties getProperties() {
+	public Map<String, String> getProperties() {
 		return this.properties;
 	}
 
 	/**
 	 * @param properties The Properties instance that should be used for saving and loading.
 	 */
-	public void setProperties(final Properties properties) {
+	public void setProperties(final Map<String, String> properties) {
 		this.properties= properties;
 	}
 	
@@ -351,7 +351,7 @@ public class PersistenceDialog extends Dialog {
 	 * @return The name of the current active view configuration
 	 */
 	public String getActiveViewConfigurationName() {
-		return this.properties.getProperty(ACTIVE_VIEW_CONFIGURATION_KEY);
+		return this.properties.get(ACTIVE_VIEW_CONFIGURATION_KEY);
 	}
 	
 	/**
@@ -362,7 +362,7 @@ public class PersistenceDialog extends Dialog {
 	 * @param name The name of the current active view configuration
 	 */
 	public void setActiveViewConfigurationName(final String name) {
-		this.properties.setProperty(ACTIVE_VIEW_CONFIGURATION_KEY, name);
+		this.properties.put(ACTIVE_VIEW_CONFIGURATION_KEY, name);
 	}
 	
 	/**
@@ -417,7 +417,7 @@ public class PersistenceDialog extends Dialog {
 		private final Styler italicStyler;
 		
 		ViewConfigurationNameLabelProvider() {
-			this.italicFont= GUIHelper.getFont(new FontData[]{new FontData("Arial", 8, SWT.ITALIC)}); //$NON-NLS-1$
+			this.italicFont= GUIHelper.getFont(new FontData("Arial", 8, SWT.ITALIC)); //$NON-NLS-1$
 			this.italicStyler= new Styler() {
 				@Override
 				public void applyStyles(final TextStyle textStyle) {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/ColumnResizeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/ColumnResizeEvent.java
deleted file mode 100644
index c106c686..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/ColumnResizeEvent.java
+++ /dev/null
@@ -1,52 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.resize;
-
-import java.util.ArrayList;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.ColumnStructuralChangeEvent;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff.DiffTypeEnum;
-
-
-public class ColumnResizeEvent extends ColumnStructuralChangeEvent {
-
-	public ColumnResizeEvent(final ILayer layer, final long columnPosition) {
-		super(layer, new LRange(columnPosition));
-	}
-	
-	protected ColumnResizeEvent(final ColumnResizeEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public ColumnResizeEvent cloneEvent() {
-		return new ColumnResizeEvent(this);
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getColumnDiffs() {
-		final Collection<StructuralDiff> rowDiffs= new ArrayList<>();
-		
-		for (final LRange lRange : getColumnPositionRanges()) {
-			rowDiffs.add(new StructuralDiff(DiffTypeEnum.CHANGE, lRange, lRange));
-		}
-		
-		return rowDiffs;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/RowResizeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/RowResizeEvent.java
deleted file mode 100644
index 2c18884a..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/RowResizeEvent.java
+++ /dev/null
@@ -1,56 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.resize;
-
-import java.util.ArrayList;
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.RowStructuralChangeEvent;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff.DiffTypeEnum;
-
-
-public class RowResizeEvent extends RowStructuralChangeEvent {
-
-	public RowResizeEvent(final ILayer layer, final long rowPosition) {
-		super(layer, new LRange(rowPosition));
-	}
-	
-	public RowResizeEvent(final ILayer layer, final LRange rowPositionRange) {
-		super(layer, rowPositionRange);
-	}
-	
-	protected RowResizeEvent(final RowResizeEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public RowResizeEvent cloneEvent() {
-		return new RowResizeEvent(this);
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getRowDiffs() {
-		final Collection<StructuralDiff> rowDiffs= new ArrayList<>();
-		
-		for (final LRange lRange : getRowPositionRanges()) {
-			new StructuralDiff(DiffTypeEnum.CHANGE, lRange, lRange);
-		}
-		
-		return rowDiffs;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/ColumnSelectionEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/ColumnSelectionEvent.java
deleted file mode 100644
index da6ecd51..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/ColumnSelectionEvent.java
+++ /dev/null
@@ -1,79 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.selection;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.selection.SelectionLayer.NO_SELECTION;
-
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.ColumnVisualChangeEvent;
-
-
-public class ColumnSelectionEvent extends ColumnVisualChangeEvent implements ISelectionEvent {
-	
-	
-	private final SelectionLayer selectionLayer;
-	
-	private long columnPositionToReveal;
-	
-	
-	public ColumnSelectionEvent(final SelectionLayer selectionLayer,
-			final long columnPosition, final boolean revealColumn) {
-		this(selectionLayer, new LRangeList(columnPosition),
-				(revealColumn) ? columnPosition : NO_SELECTION );
-	}
-	
-	public ColumnSelectionEvent(final SelectionLayer selectionLayer,
-			final Collection<LRange> columnPositions, final long columnPositionToReveal) {
-		super(selectionLayer, columnPositions);
-		this.selectionLayer= selectionLayer;
-		this.columnPositionToReveal= columnPositionToReveal;
-	}
-	
-	protected ColumnSelectionEvent(final ColumnSelectionEvent event) {
-		super(event);
-		this.selectionLayer= event.selectionLayer;
-		this.columnPositionToReveal= event.columnPositionToReveal;
-	}
-	
-	@Override
-	public ColumnSelectionEvent cloneEvent() {
-		return new ColumnSelectionEvent(this);
-	}
-	
-	
-	@Override
-	public SelectionLayer getSelectionLayer() {
-		return this.selectionLayer;
-	}
-	
-	public long getColumnPositionToReveal() {
-		return this.columnPositionToReveal;
-	}
-	
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		if (this.columnPositionToReveal != NO_SELECTION) {
-			this.columnPositionToReveal= localLayer.getDim(HORIZONTAL).underlyingToLocalPosition(
-					getLayer().getDim(HORIZONTAL), this.columnPositionToReveal );
-		}
-		
-		return super.convertToLocal(localLayer);
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/IRowSelectionModel.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/IRowSelectionModel.java
deleted file mode 100644
index 63f08754..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/IRowSelectionModel.java
+++ /dev/null
@@ -1,35 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.selection;
-
-import java.util.List;
-
-
-public interface IRowSelectionModel<R> extends ISelectionModel {
-
-	/**
-	 * Expose the underlying row objects
-	 * 
-	 * @return
-	 */
-	public List<R> getSelectedRowObjects();
-	
-	/**
-	 * Removes the selected row object from the selection
-	 * 
-	 * @param rowObject
-	 */
-	public void clearSelection(R rowObject);
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/RowSelectionEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/RowSelectionEvent.java
deleted file mode 100644
index 3edee0ce..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/RowSelectionEvent.java
+++ /dev/null
@@ -1,79 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.selection;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
-import static org.eclipse.statet.ecommons.waltable.selection.SelectionLayer.NO_SELECTION;
-
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.RowVisualChangeEvent;
-
-
-public class RowSelectionEvent extends RowVisualChangeEvent implements ISelectionEvent {
-	
-	
-	private final SelectionLayer selectionLayer;
-	
-	private long rowPositionToReveal;
-	
-	
-	public RowSelectionEvent(final SelectionLayer selectionLayer,
-			final long rowPosition, final boolean revealRow) {
-		this(selectionLayer, new LRangeList(rowPosition),
-				(revealRow) ? rowPosition : NO_SELECTION );
-	}
-	
-	public RowSelectionEvent(final SelectionLayer selectionLayer,
-			final Collection<LRange> rowPositions, final long rowPositionToReveal) {
-		super(selectionLayer, rowPositions);
-		this.selectionLayer= selectionLayer;
-		this.rowPositionToReveal= rowPositionToReveal;
-	}
-	
-	protected RowSelectionEvent(final RowSelectionEvent event) {
-		super(event);
-		this.selectionLayer= event.selectionLayer;
-		this.rowPositionToReveal= event.rowPositionToReveal;
-	}
-	
-	@Override
-	public RowSelectionEvent cloneEvent() {
-		return new RowSelectionEvent(this);
-	}
-	
-	
-	@Override
-	public SelectionLayer getSelectionLayer() {
-		return this.selectionLayer;
-	}
-	
-	public long getRowPositionToReveal() {
-		return this.rowPositionToReveal;
-	}
-	
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		if (this.rowPositionToReveal != NO_SELECTION) {
-			this.rowPositionToReveal= localLayer.getDim(VERTICAL).underlyingToLocalPosition(
-					getLayer().getDim(VERTICAL), this.rowPositionToReveal );
-		}
-		
-		return super.convertToLocal(localLayer);
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionFlags.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionFlags.java
deleted file mode 100644
index f3beadea..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionFlags.java
+++ /dev/null
@@ -1,39 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.selection;
-
-import org.eclipse.swt.SWT;
-
-
-public class SelectionFlags {
-	
-	
-	/** Extend current selection */
-	public static final int RANGE_SELECTION= SWT.SHIFT;
-	/** Retain or toggle */
-	public static final int RETAIN_SELECTION= SWT.CTRL;
-	
-	
-	public static final int swt2Flags(final int swtMask) {
-		int flags= 0;
-		if ((swtMask & SWT.MOD2) != 0) {
-			flags |= RANGE_SELECTION;
-		}
-		if ((swtMask & SWT.MOD1) != 0) {
-			flags |= RETAIN_SELECTION;
-		}
-		return flags;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionLayerStructuralChangeEventHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionLayerStructuralChangeEventHandler.java
deleted file mode 100644
index bcd40600..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionLayerStructuralChangeEventHandler.java
+++ /dev/null
@@ -1,96 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.selection;
-
-import java.util.Collection;
-import java.util.List;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEventHandler;
-import org.eclipse.statet.ecommons.waltable.layer.event.IStructuralChangeEvent;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff.DiffTypeEnum;
-
-
-public class SelectionLayerStructuralChangeEventHandler implements ILayerEventHandler<IStructuralChangeEvent> {
-
-	private final ISelectionModel selectionModel;
-	private final SelectionLayer selectionLayer;
-	
-	public SelectionLayerStructuralChangeEventHandler(final SelectionLayer selectionLayer, final ISelectionModel selectionModel) {
-		this.selectionLayer= selectionLayer;
-		this.selectionModel= selectionModel;
-	}
-
-	@Override
-	public Class<IStructuralChangeEvent> getLayerEventClass() {
-		return IStructuralChangeEvent.class;
-	}
-
-	@Override
-	public void handleLayerEvent(final IStructuralChangeEvent event) {
-		if (event.isHorizontalStructureChanged()) {
-			// TODO handle column deletion
-			this.selectionLayer.clear();
-			return;
-		}
-		
-		if (event.isVerticalStructureChanged()) {
-			//if there are no row diffs, it seems to be a complete refresh
-			if (event.getRowDiffs() == null) {
-				final Collection<LRectangle> lRectangles= event.getChangedPositionRectangles();
-				for (final LRectangle lRectangle : lRectangles) {
-					final LRange changedRange= new LRange(lRectangle.y, lRectangle.y + lRectangle.height);
-					if (selectedRowModified(changedRange)) {
-						if (this.selectionLayer.getRowCount() > 0) {
-							long columnPosition= this.selectionLayer.getSelectionAnchor().columnPosition;
-							if (columnPosition == SelectionLayer.NO_SELECTION) {
-								columnPosition= 0;
-							}
-							this.selectionLayer.setSelectionToCell(columnPosition, 0, false);
-						}
-						else {
-							this.selectionLayer.clear();
-						}
-						return;
-					}
-				}
-			}
-			else {
-				//there are row diffs so we try to determine the diffs to process
-				for (final StructuralDiff diff : event.getRowDiffs()) {
-					//DiffTypeEnum.CHANGE is used for resizing and shouldn't result in clearing the selection
-					if (diff.getDiffType() != DiffTypeEnum.CHANGE) {
-						if (selectedRowModified(diff.getBeforePositionRange())) {
-							this.selectionLayer.clear();
-							return;
-						}
-					}
-				}
-			}
-		}
-	}
-	
-	private boolean selectedRowModified(final LRange changedRange){
-		final List<LRange> selectedRows= this.selectionModel.getSelectedRowPositions();
-		for (final LRange rowRange : selectedRows) {
-			if (rowRange.overlap(changedRange)){
-				return true;
-			}
-		}
-		return false;
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionStyleConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionStyleConfiguration.java
deleted file mode 100644
index 370ce283..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionStyleConfiguration.java
+++ /dev/null
@@ -1,126 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.selection.config;
-
-import org.eclipse.swt.SWT;
-import org.eclipse.swt.graphics.Color;
-import org.eclipse.swt.graphics.Font;
-import org.eclipse.swt.graphics.FontData;
-
-import org.eclipse.statet.ecommons.waltable.config.AbstractRegistryConfiguration;
-import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle.LineStyle;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.SelectionStyleLabels;
-import org.eclipse.statet.ecommons.waltable.style.Style;
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
-
-
-/**
- * Sets up rendering style used for selected areas and the selection anchor.
- */
-public class DefaultSelectionStyleConfiguration extends AbstractRegistryConfiguration {
-	
-	// Selection style
-	public Font selectionFont= GUIHelper.getFont(new FontData("Verdana", 8, SWT.BOLD | SWT.ITALIC)); //$NON-NLS-1$
-	public Color selectionBgColor= GUIHelper.COLOR_TITLE_INACTIVE_BACKGROUND;
-	public Color selectionFgColor= GUIHelper.COLOR_BLACK;
-	
-	// Anchor style
-	public Color anchorBorderColor= GUIHelper.COLOR_DARK_GRAY;
-	public BorderStyle anchorBorderStyle= new BorderStyle(1, this.anchorBorderColor, LineStyle.SOLID);
-	public Color anchorBgColor= GUIHelper.COLOR_GRAY;
-	public Color anchorFgColor= GUIHelper.COLOR_WHITE;
-	
-	// Selected headers style
-	public Color selectedHeaderBgColor= GUIHelper.COLOR_GRAY;
-	public Color selectedHeaderFgColor= GUIHelper.COLOR_WHITE;
-	public Font selectedHeaderFont= GUIHelper.getFont(new FontData("Verdana", 10, SWT.BOLD)); //$NON-NLS-1$
-	public BorderStyle selectedHeaderBorderStyle= new BorderStyle(-1, this.selectedHeaderFgColor, LineStyle.SOLID);
-	
-	// Anchor grid line style
-	public Color anchorGridBorderColor= GUIHelper.COLOR_BLACK;
-	public BorderStyle anchorGridBorderStyle= new BorderStyle(1, this.anchorGridBorderColor, LineStyle.DOTTED);
-	
-	
-	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
-		configureSelectionStyle(configRegistry);
-		configureSelectionAnchorStyle(configRegistry);
-		configureSelectionAnchorGridLineStyle(configRegistry);
-		configureHeaderHasSelectionStyle(configRegistry);
-		configureHeaderFullySelectedStyle(configRegistry);
-	}
-	
-	protected void configureSelectionStyle(final IConfigRegistry configRegistry) {
-		final Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.FONT, this.selectionFont);
-		cellStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR, this.selectionBgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.FOREGROUND_COLOR, this.selectionFgColor);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
-				DisplayMode.SELECT );
-	}
-	
-	protected void configureSelectionAnchorStyle(final IConfigRegistry configRegistry) {
-		// Selection anchor style for normal display mode
-		Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.BORDER_STYLE, this.anchorBorderStyle);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
-				DisplayMode.NORMAL, SelectionStyleLabels.SELECTION_ANCHOR_STYLE );
-		
-		// Selection anchor style for select display mode
-		cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR, this.anchorBgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.FOREGROUND_COLOR, this.anchorFgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.BORDER_STYLE, this.anchorBorderStyle);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
-				DisplayMode.SELECT, SelectionStyleLabels.SELECTION_ANCHOR_STYLE );
-	}
-	
-	protected void configureSelectionAnchorGridLineStyle(final IConfigRegistry configRegistry) {
-		final Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.BORDER_STYLE, this.anchorGridBorderStyle);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
-				DisplayMode.SELECT, SelectionStyleLabels.SELECTION_ANCHOR_GRID_LINE_STYLE );
-	}
-	
-	protected void configureHeaderHasSelectionStyle(final IConfigRegistry configRegistry) {
-		final Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.FOREGROUND_COLOR, this.selectedHeaderFgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR, this.selectedHeaderBgColor);
-		cellStyle.setAttributeValue(CellStyleAttributes.FONT, this.selectedHeaderFont);
-		cellStyle.setAttributeValue(CellStyleAttributes.BORDER_STYLE, this.selectedHeaderBorderStyle);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
-				DisplayMode.SELECT, GridRegion.COLUMN_HEADER );
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
-				DisplayMode.SELECT, GridRegion.CORNER );
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
-				DisplayMode.SELECT, GridRegion.ROW_HEADER );
-	}
-	
-	protected void configureHeaderFullySelectedStyle(final IConfigRegistry configRegistry) {
-		// Header fully selected
-		final Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR, GUIHelper.COLOR_WIDGET_NORMAL_SHADOW);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
-				DisplayMode.SELECT, SelectionStyleLabels.COLUMN_FULLY_SELECTED_STYLE);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
-				DisplayMode.SELECT, SelectionStyleLabels.ROW_FULLY_SELECTED_STYLE);
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/ClearSortCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/ClearSortCommandHandler.java
deleted file mode 100644
index f947e7a4..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/ClearSortCommandHandler.java
+++ /dev/null
@@ -1,75 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.sort;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-
-import java.util.List;
-
-import org.eclipse.swt.custom.BusyIndicator;
-
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-
-
-public class ClearSortCommandHandler implements ILayerCommandHandler<ClearSortCommand> {
-	
-	
-	private final ISortModel sortModel;
-	
-	
-	public ClearSortCommandHandler(final ISortModel sortModel) {
-		this.sortModel= sortModel;
-	}
-	
-	
-	@Override
-	public Class<ClearSortCommand> getCommandClass() {
-		return ClearSortCommand.class;
-	}
-	
-	
-	@Override
-	public boolean doCommand(final ILayer targetLayer, final ClearSortCommand command) {
-		// with busy indicator
-		final Runnable sortRunner= new Runnable() {
-			@Override
-			public void run() {
-				final ILayerDim dim= targetLayer.getDim(HORIZONTAL);
-				
-				final List<Long> sortedIds= ClearSortCommandHandler.this.sortModel.getSortedColumnIds();
-				final LRangeList sortedPositions= new LRangeList();
-				for (final Long id : sortedIds) {
-					final long position= dim.getPositionById(id);
-					if (position != ILayerDim.POSITION_NA) {
-						sortedPositions.values().add(position);
-					}
-				}
-				
-				ClearSortCommandHandler.this.sortModel.clear();
-				
-				// Fire event
-				final SortColumnEvent sortEvent= new SortColumnEvent(dim,
-						sortedPositions );
-				dim.getLayer().fireLayerEvent(sortEvent);
-			}
-		};
-		BusyIndicator.showWhile(null, sortRunner);
-		
-		return true;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortColumnEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortColumnEvent.java
deleted file mode 100644
index 391bbb0a..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortColumnEvent.java
+++ /dev/null
@@ -1,43 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.sort;
-
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.event.ColumnVisualChangeEvent;
-
-
-public class SortColumnEvent extends ColumnVisualChangeEvent {
-	
-	
-	public SortColumnEvent(final ILayerDim layer, final long columnPosition) {
-		super(layer.getLayer(), new LRange(columnPosition));
-	}
-	
-	public SortColumnEvent(final ILayerDim layer, final Collection<LRange> columnPositions) {
-		super(layer.getLayer(), columnPositions);
-	}
-	
-	protected SortColumnEvent(final SortColumnEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public SortColumnEvent cloneEvent() {
-		return new SortColumnEvent(this);
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortConfigAttributes.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortConfigAttributes.java
deleted file mode 100644
index 74b798b0..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortConfigAttributes.java
+++ /dev/null
@@ -1,25 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.sort;
-
-import java.util.Comparator;
-
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
-
-
-public interface SortConfigAttributes {
-	
-	public static final ConfigAttribute<Comparator<?>> SORT_COMPARATOR= new ConfigAttribute<>();
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortPositionCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortPositionCommandHandler.java
deleted file mode 100644
index 708c0292..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortPositionCommandHandler.java
+++ /dev/null
@@ -1,69 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.sort;
-
-import org.eclipse.swt.custom.BusyIndicator;
-
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-
-
-/**
- * Handle sort commands
- */
-public class SortPositionCommandHandler extends AbstractLayerCommandHandler<SortDimPositionCommand> {
-	
-	
-	private final ISortModel sortModel;
-	
-	
-	public SortPositionCommandHandler(final ISortModel sortModel) {
-		this.sortModel= sortModel;
-	}
-	
-	
-	@Override
-	public Class<SortDimPositionCommand> getCommandClass() {
-		return SortDimPositionCommand.class;
-	}
-	
-	@Override
-	protected boolean doCommand(final SortDimPositionCommand command) {
-		final long columnId= command.getDim()
-				.getPositionId(command.getPosition(), command.getPosition());
-		
-		// with busy indicator
-		final Runnable sortRunner= new Runnable() {
-			@Override
-			public void run() {
-				final ILayerDim dim= command.getDim();
-				
-				final SortDirection newSortDirection= (command.getDirection() != null) ?
-						command.getDirection() :
-							SortPositionCommandHandler.this.sortModel.getSortDirection(columnId).getNextSortDirection();
-				SortPositionCommandHandler.this.sortModel.sort(columnId,
-						newSortDirection, command.isAccumulate() );
-				
-				// Fire event
-				final SortColumnEvent sortEvent= new SortColumnEvent(dim,
-						command.getPosition() );
-				dim.getLayer().fireLayerEvent(sortEvent);
-			}
-		};
-		BusyIndicator.showWhile(null, sortRunner);
-		
-		return true;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleAttributes.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleAttributes.java
deleted file mode 100644
index 0ac872e3..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleAttributes.java
+++ /dev/null
@@ -1,87 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.style;
-
-import org.eclipse.swt.graphics.Color;
-import org.eclipse.swt.graphics.Font;
-import org.eclipse.swt.graphics.Image;
-
-
-public interface CellStyleAttributes {
-    
-	/**
-	 * Attribute for configuring the background color of a cell.
-	 */
-    public static final ConfigAttribute<Color> BACKGROUND_COLOR= new ConfigAttribute<>();
-    
-	/**
-	 * Attribute for configuring the foreground color of a cell.
-	 */
-    public static final ConfigAttribute<Color> FOREGROUND_COLOR= new ConfigAttribute<>();
-    
-    /**
-     * Attribute for configuring the gradient sweeping background color.
-     * Is used by the GradientBackgroundPainter.
-     */
-    public static final ConfigAttribute<Color> GRADIENT_BACKGROUND_COLOR= new ConfigAttribute<>();
-    
-    /**
-     * Attribute for configuring the gradient sweeping foreground color.
-     * Is used by the GradientBackgroundPainter.
-     */
-    public static final ConfigAttribute<Color> GRADIENT_FOREGROUND_COLOR= new ConfigAttribute<>();
-    
-    /**
-     * Attribute for configuring the horizontal alignment of a cell.
-     */
-    public static final ConfigAttribute<HorizontalAlignment> HORIZONTAL_ALIGNMENT= new ConfigAttribute<>();
-    
-    /**
-     * Attribute for configuring the vertical alignment of a cell.
-     */
-    public static final ConfigAttribute<VerticalAlignment> VERTICAL_ALIGNMENT= new ConfigAttribute<>();
-    
-    /**
-     * Attribute for configuring the font to be used on rendering text.
-     * Is used by all specialisations of the AbstractTextPainter.
-     */
-    public static final ConfigAttribute<Font> FONT= new ConfigAttribute<>();
-    
-    /**
-     * Attribute for configuring the image to rendered.
-     * Is used by the ImagePainter to determine the image to render dynamically.
-     */
-    public static final ConfigAttribute<Image> IMAGE= new ConfigAttribute<>();
-    
-    /**
-     * Attribute for configuring the border style.
-     * Is used by the LineBorderDecorator.
-     */
-    public static final ConfigAttribute<BorderStyle> BORDER_STYLE= new ConfigAttribute<>();
-    
-    /**
-     * Attribute for configuring the echo character that should be used by PasswordTextPainter and
-     * PasswordCellEditor.
-     */
-	public static final ConfigAttribute<Character> PASSWORD_ECHO_CHAR= new ConfigAttribute<>();
-	
-	/**
-	 * Attribute for configuring the text decoration (underline and/or strikethrough).
-	 * Is used by all specialisations of the AbstractTextPainter
-	 */
-	public static final ConfigAttribute<TextDecorationEnum> TEXT_DECORATION= new ConfigAttribute<>();
-	
-	public static final ConfigAttribute<Font> CONTROL_FONT= new ConfigAttribute<>();
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleProxy.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleProxy.java
deleted file mode 100644
index dfc2b785..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleProxy.java
+++ /dev/null
@@ -1,36 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.style;
-
-import java.util.List;
-
-import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-
-
-public class CellStyleProxy extends StyleProxy {
-	
-	
-	public CellStyleProxy(final IConfigRegistry configRegistry,
-			final DisplayMode targetDisplayMode, final List<String> configLabels) {
-		super(CellConfigAttributes.CELL_STYLE, configRegistry, targetDisplayMode, configLabels);
-	}
-	
-	
-	@Override
-	public <T> void setAttributeValue(final ConfigAttribute<T> styleAttribute, final T value) {
-		throw new UnsupportedOperationException("Not implemented yet"); //$NON-NLS-1$
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleUtil.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleUtil.java
index 2cdc5d67..a16f6952 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleUtil.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/CellStyleUtil.java
@@ -19,25 +19,31 @@ import java.util.List;
 import org.eclipse.swt.graphics.Color;
 
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.RegistryStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.style.VerticalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
 
 
 public class CellStyleUtil {
 
-	public static IStyle getCellStyle(final ILayerCell cell, final IConfigRegistry configRegistry) {
-		return new CellStyleProxy(configRegistry, cell.getDisplayMode(), cell.getConfigLabels().getLabels());
+	public static Style getCellStyle(final LayerCell cell, final ConfigRegistry configRegistry) {
+		return new RegistryStyle(configRegistry, CellConfigAttributes.CELL_STYLE, cell.getDisplayMode(), cell.getLabels().getLabels());
 	}
 
-	public static int getHorizontalAlignmentSWT(final IStyle cellStyle, final int swtDefault) {
-		final HorizontalAlignment horizontalAlignment= cellStyle.getAttributeValue(CellStyleAttributes.HORIZONTAL_ALIGNMENT);
-		return (horizontalAlignment != null) ? SWTUtil.toSWT(horizontalAlignment) : swtDefault;
+	public static int getHorizontalAlignmentSWT(final Style cellStyle, final int swtDefault) {
+		final HorizontalAlignment horizontalAlignment= cellStyle.getAttributeValue(CellStyling.HORIZONTAL_ALIGNMENT);
+		return (horizontalAlignment != null) ? SwtUtils.toSWT(horizontalAlignment) : swtDefault;
 	}
 
-	public static long getHorizontalAlignmentPadding(final IStyle cellStyle, final LRectangle lRectangle, final long contentWidth) {
-		final HorizontalAlignment horizontalAlignment= cellStyle.getAttributeValue(CellStyleAttributes.HORIZONTAL_ALIGNMENT);
+	public static long getHorizontalAlignmentPadding(final Style cellStyle, final LRectangle lRectangle, final long contentWidth) {
+		final HorizontalAlignment horizontalAlignment= cellStyle.getAttributeValue(CellStyling.HORIZONTAL_ALIGNMENT);
 		return getHorizontalAlignmentPadding(horizontalAlignment, lRectangle.width, contentWidth);
 	}
 	
@@ -70,8 +76,8 @@ public class CellStyleUtil {
 		return padding;
 	}
 
-	public static long getVerticalAlignmentPadding(final IStyle cellStyle, final LRectangle lRectangle, final long contentHeight) {
-		final VerticalAlignment verticalAlignment= cellStyle.getAttributeValue(CellStyleAttributes.VERTICAL_ALIGNMENT);
+	public static long getVerticalAlignmentPadding(final Style cellStyle, final LRectangle lRectangle, final long contentHeight) {
+		final VerticalAlignment verticalAlignment= cellStyle.getAttributeValue(CellStyling.VERTICAL_ALIGNMENT);
 		return getVerticalAlignmentPadding(verticalAlignment, lRectangle.height, contentHeight);
 	}
 	
@@ -101,20 +107,20 @@ public class CellStyleUtil {
 		return padding;
 	}
 	
-	public static List<Color> getAllBackgroundColors(final ILayerCell cell, final IConfigRegistry configRegistry,
+	public static List<Color> getAllBackgroundColors(final LayerCell cell, final ConfigRegistry configRegistry,
 			final DisplayMode displayMode) {
 		
 		final List<Color> colors= new ArrayList<>();
 		
-		for (final String configLabel : cell.getConfigLabels().getLabels()) {
-			final IStyle cellStyle= configRegistry.getSpecificConfigAttribute(CellConfigAttributes.CELL_STYLE, displayMode, configLabel);
+		for (final String configLabel : cell.getLabels().getLabels()) {
+			final Style cellStyle= configRegistry.getSpecificAttribute(CellConfigAttributes.CELL_STYLE, displayMode, configLabel);
 			if (cellStyle != null) {
-				final Color color= cellStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
+				final Color color= cellStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR);
 				
 				if (color != null) {
 					colors.add(color);
 				}
-			}			
+			}
 		}
 		
 		return colors;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/DefaultDisplayModeOrdering.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/DefaultDisplayModeOrdering.java
deleted file mode 100644
index 542f943a..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/DefaultDisplayModeOrdering.java
+++ /dev/null
@@ -1,53 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.style;
-
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.List;
-
-
-public class DefaultDisplayModeOrdering implements IDisplayModeLookupStrategy {
-	
-	private static final List<DisplayMode> NORMAL_ORDERING= Arrays.asList(DisplayMode.NORMAL);
-	
-	private static final List<DisplayMode> HOVER_ORDERING= Arrays.asList(DisplayMode.HOVER, DisplayMode.NORMAL);
-	
-	private static final List<DisplayMode> SELECT_ORDERING= Arrays.asList(DisplayMode.SELECT, DisplayMode.NORMAL);
-	
-	private static final List<DisplayMode> EDIT_ORDERING= Arrays.asList(DisplayMode.EDIT, DisplayMode.NORMAL);
-	
-	private static final List<DisplayMode> EMPTY_ORDERING= Collections.emptyList();
-	
-	
-	/**
-	 * See DefaultDisplayModeOrderingTest
-	 */
-	@Override
-	public List<DisplayMode> getDisplayModeOrdering(final DisplayMode targetDisplayMode) {
-		switch (targetDisplayMode) {
-		case NORMAL:
-			return NORMAL_ORDERING;
-		case HOVER:
-			return HOVER_ORDERING;
-		case SELECT:
-			return SELECT_ORDERING;
-		case EDIT:
-			return EDIT_ORDERING;
-		default:
-			return EMPTY_ORDERING;
-		}
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/SelectionStyleLabels.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/SelectionStyleLabels.java
index 179d9a37..55e6b761 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/SelectionStyleLabels.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/SelectionStyleLabels.java
@@ -13,17 +13,17 @@
 
 package org.eclipse.statet.ecommons.waltable.style;
 
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 
 
 public interface SelectionStyleLabels {
     
-    public static final String SELECTION_ANCHOR_STYLE= "selectionAnchor"; //$NON-NLS-1$
+    public static final String SELECTION_ANCHOR_STYLE= "SELECTION_ANCHOR"; //$NON-NLS-1$
     
     public static final String SELECTION_ANCHOR_GRID_LINE_STYLE= "selectionAnchorGridLine"; //$NON-NLS-1$
 
-    public static final String COLUMN_FULLY_SELECTED_STYLE= GridRegion.COLUMN_HEADER + "_FULL"; //$NON-NLS-1$
+    public static final String COLUMN_FULLY_SELECTED_STYLE= GridLabels.COLUMN_HEADER + "_FULL"; //$NON-NLS-1$
     
-    public static final String ROW_FULLY_SELECTED_STYLE= GridRegion.ROW_HEADER + "_FULL"; //$NON-NLS-1$
+    public static final String ROW_FULLY_SELECTED_STYLE= GridLabels.ROW_HEADER + "_FULL"; //$NON-NLS-1$
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/StyleProxy.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/StyleProxy.java
deleted file mode 100644
index 3983242d..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/StyleProxy.java
+++ /dev/null
@@ -1,69 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.style;
-
-import java.util.List;
-
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-
-
-public abstract class StyleProxy implements IStyle {
-	
-	
-	private final ConfigAttribute<IStyle> styleConfigAttribute;
-	private final IConfigRegistry configRegistry;
-	private final DisplayMode targetDisplayMode;
-	private final List<String> configLabels;
-	
-	
-	public StyleProxy(final ConfigAttribute<IStyle> styleConfigAttribute,
-			final IConfigRegistry configRegistry,
-			final DisplayMode targetDisplayMode, final List<String> configLabels) {
-		this.styleConfigAttribute= styleConfigAttribute;
-		this.configRegistry= configRegistry;
-		this.targetDisplayMode= targetDisplayMode;
-		this.configLabels= configLabels;
-	}
-	
-	
-	@Override
-	public <T> T getAttributeValue(final ConfigAttribute<T> styleAttribute) {
-		T styleAttributeValue= null;
-		final IDisplayModeLookupStrategy displayModeLookupStrategy= this.configRegistry.getDisplayModeOrdering();
-		
-		for (final DisplayMode displayMode : displayModeLookupStrategy.getDisplayModeOrdering(this.targetDisplayMode)) {
-			for (final String configLabel : this.configLabels) {
-				final IStyle cellStyle= this.configRegistry.getSpecificConfigAttribute(this.styleConfigAttribute, displayMode, configLabel);
-				if (cellStyle != null) {
-					styleAttributeValue= cellStyle.getAttributeValue(styleAttribute);
-					if (styleAttributeValue != null) {
-						return styleAttributeValue;
-					}
-				}
-			}
-			
-			// default
-			final IStyle cellStyle= this.configRegistry.getSpecificConfigAttribute(this.styleConfigAttribute, displayMode, null);
-			if (cellStyle != null) {
-				styleAttributeValue= cellStyle.getAttributeValue(styleAttribute);
-				if (styleAttributeValue != null) {
-					return styleAttributeValue;
-				}
-			}
-		}
-		
-		return null;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/BorderStyleEditorPanel.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/BorderStyleEditorPanel.java
index a6d1e1f5..58c158f3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/BorderStyleEditorPanel.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/BorderStyleEditorPanel.java
@@ -25,8 +25,8 @@ import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Label;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle.LineStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle.LineStyle;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/BorderThicknessPicker.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/BorderThicknessPicker.java
index 2a11077f..ca1d1ab3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/BorderThicknessPicker.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/BorderThicknessPicker.java
@@ -34,11 +34,11 @@ public class BorderThicknessPicker extends Composite {
         super(parent, NONE);
         setLayout(new RowLayout());
 
-        this.combo= new Combo(this, SWT.READ_ONLY | SWT.DROP_DOWN);
-        this.combo.setItems(new String[] { 
-        		Messages.getString("BorderThicknessPicker.thin"),  //$NON-NLS-1$
-        		Messages.getString("BorderThicknessPicker.thick"),  //$NON-NLS-1$
-        		Messages.getString("BorderThicknessPicker.veryThick")}); //$NON-NLS-1$
+		this.combo= new Combo(this, SWT.READ_ONLY | SWT.DROP_DOWN);
+		this.combo.setItems( 
+				Messages.getString("BorderThicknessPicker.thin"),  //$NON-NLS-1$
+				Messages.getString("BorderThicknessPicker.thick"),  //$NON-NLS-1$
+				Messages.getString("BorderThicknessPicker.veryThick") ); //$NON-NLS-1$
         this.combo.select(0);
     }
     
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/CellStyleEditorPanel.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/CellStyleEditorPanel.java
index a3e6d54b..ede28694 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/CellStyleEditorPanel.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/CellStyleEditorPanel.java
@@ -22,10 +22,11 @@ import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Label;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
-import org.eclipse.statet.ecommons.waltable.style.Style;
-import org.eclipse.statet.ecommons.waltable.style.VerticalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.style.VerticalAlignment;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -80,27 +81,27 @@ public class CellStyleEditorPanel extends AbstractEditorPanel<Style> {
 
     @Override
     public void edit(final Style style) throws Exception {
-        this.origBgColor= style.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
+        this.origBgColor= style.getAttributeValue(CellStyling.BACKGROUND_COLOR);
         if (this.origBgColor == null) {
         	this.origBgColor= GUIHelper.COLOR_WHITE;
         }
 		this.backgroundColorPicker.setSelectedColor(this.origBgColor);
 
-        this.origFgColor= style.getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR);
+        this.origFgColor= style.getAttributeValue(CellStyling.FOREGROUND_COLOR);
         if (this.origFgColor == null) {
         	this.origFgColor= GUIHelper.COLOR_BLACK;
         }
 		this.foregroundColorPicker.setSelectedColor(this.origFgColor);
 
-		this.fontPicker.setOriginalFont(style.getAttributeValue(CellStyleAttributes.FONT));
+		this.fontPicker.setOriginalFont(style.getAttributeValue(CellStyling.FONT));
 
-        this.origHAlign= style.getAttributeValue(CellStyleAttributes.HORIZONTAL_ALIGNMENT);
+        this.origHAlign= style.getAttributeValue(CellStyling.HORIZONTAL_ALIGNMENT);
         if (this.origHAlign == null) {
         	this.origHAlign= HorizontalAlignment.CENTER;
         }
 		this.horizontalAlignmentPicker.setSelectedAlignment(this.origHAlign);
 
-        this.origVAlign= style.getAttributeValue(CellStyleAttributes.VERTICAL_ALIGNMENT);
+        this.origVAlign= style.getAttributeValue(CellStyling.VERTICAL_ALIGNMENT);
         if (this.origVAlign == null) {
         	this.origVAlign= VerticalAlignment.MIDDLE;
         }
@@ -108,23 +109,23 @@ public class CellStyleEditorPanel extends AbstractEditorPanel<Style> {
     }
 
     @Override
-    public Style getNewValue() {
-    	final Style newStyle= new Style();
+    public BasicStyle getNewValue() {
+    	final BasicStyle newStyle= new BasicStyle();
     	
     	final Color bgColor= this.backgroundColorPicker.getSelectedColor();
-    	newStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR, bgColor);
+    	newStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR, bgColor);
     	
     	final Color fgColor= this.foregroundColorPicker.getSelectedColor();
-    	newStyle.setAttributeValue(CellStyleAttributes.FOREGROUND_COLOR, fgColor);
+    	newStyle.setAttributeValue(CellStyling.FOREGROUND_COLOR, fgColor);
     	
     	final Font font= this.fontPicker.getSelectedFont();
-		newStyle.setAttributeValue(CellStyleAttributes.FONT, font);
+		newStyle.setAttributeValue(CellStyling.FONT, font);
 		
     	final HorizontalAlignment hAlign= this.horizontalAlignmentPicker.getSelectedAlignment();
-    	newStyle.setAttributeValue(CellStyleAttributes.HORIZONTAL_ALIGNMENT, hAlign);
+    	newStyle.setAttributeValue(CellStyling.HORIZONTAL_ALIGNMENT, hAlign);
     	
     	final VerticalAlignment vAlign= this.verticalAlignmentPicker.getSelectedAlignment();
-		newStyle.setAttributeValue(CellStyleAttributes.VERTICAL_ALIGNMENT, vAlign);
+		newStyle.setAttributeValue(CellStyling.VERTICAL_ALIGNMENT, vAlign);
 		
     	return newStyle;
     }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/ColorPicker.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/ColorPicker.java
index b5393f0c..17a5dca4 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/ColorPicker.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/ColorPicker.java
@@ -27,8 +27,6 @@ import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Shell;
 
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
-
 
 /**
  * A button that displays a solid block of color and allows the user to pick a color. The user can double click on the
@@ -73,7 +71,7 @@ public class ColorPicker extends CLabel {
     }
 
     private void update(final RGB selected) {
-        this.selectedColor= GUIHelper.getColor(selected);
+        this.selectedColor= new Color(selected);
         setImage(getColorImage(this.selectedColor));
     }
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/ColumnStyleEditorDialog.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/ColumnStyleEditorDialog.java
index 5f043f53..66e1ef93 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/ColumnStyleEditorDialog.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/ColumnStyleEditorDialog.java
@@ -24,9 +24,9 @@ import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Shell;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -37,18 +37,18 @@ public class ColumnStyleEditorDialog extends AbstractStyleEditorDialog {
 	private BorderStyleEditorPanel borderStyleEditorPanel;
 
 	// These are populated on OK button press
-	protected Style newColumnCellStyle;
+	protected BasicStyle newColumnCellStyle;
 	protected BorderStyle newBorderStyle;
 
-	private final Style columnStyle;
+	private final BasicStyle columnStyle;
 
-	public ColumnStyleEditorDialog(final Shell parent, final Style columnCellStyle) {
+	public ColumnStyleEditorDialog(final Shell parent, final BasicStyle columnCellStyle) {
 		super(parent);
 		this.columnStyle= columnCellStyle;
 
 		this.newColumnCellStyle= columnCellStyle;
 		if (columnCellStyle != null) {
-			this.newBorderStyle= this.columnStyle.getAttributeValue(CellStyleAttributes.BORDER_STYLE);
+			this.newBorderStyle= this.columnStyle.getAttributeValue(CellStyling.BORDER_STYLE);
 		}
 	}
 
@@ -86,7 +86,7 @@ public class ColumnStyleEditorDialog extends AbstractStyleEditorDialog {
 
 		try {
 			this.cellStyleEditorPanel.edit(this.columnStyle);
-			this.borderStyleEditorPanel.edit(this.columnStyle.getAttributeValue(CellStyleAttributes.BORDER_STYLE));
+			this.borderStyleEditorPanel.edit(this.columnStyle.getAttributeValue(CellStyling.BORDER_STYLE));
 		} catch (final Exception e) {
 			e.printStackTrace(System.err);
 		}
@@ -139,7 +139,7 @@ public class ColumnStyleEditorDialog extends AbstractStyleEditorDialog {
 
 	// Getters for the modified style
 
-	public Style getNewColumnCellStyle() {
+	public BasicStyle getNewColumnCellStyle() {
 		return this.newColumnCellStyle;
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/DisplayColumnStyleEditorCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/DisplayColumnStyleEditorCommand.java
index a321f3e4..7459843d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/DisplayColumnStyleEditorCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/DisplayColumnStyleEditorCommand.java
@@ -13,30 +13,30 @@
 
 package org.eclipse.statet.ecommons.waltable.style.editor;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 public class DisplayColumnStyleEditorCommand extends AbstractContextFreeCommand {
 
 	public final long columnPosition;
 	public final long rowPosition;
-	private final ILayer layer;
-	private final IConfigRegistry configRegistry;
+	private final Layer layer;
+	private final ConfigRegistry configRegistry;
 
-	public DisplayColumnStyleEditorCommand(final ILayer natLayer, final IConfigRegistry configRegistry, final long columnPosition, final long rowPosition) {
+	public DisplayColumnStyleEditorCommand(final Layer natLayer, final ConfigRegistry configRegistry, final long columnPosition, final long rowPosition) {
 		this.layer= natLayer;
 		this.configRegistry= configRegistry;
 		this.columnPosition= columnPosition;
 		this.rowPosition= rowPosition;
 	}
 	
-	public ILayer getNattableLayer() {
+	public Layer getNattableLayer() {
 		return this.layer;
 	}
 
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getConfigRegistry() {
 		return this.configRegistry;
 	}
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/DisplayColumnStyleEditorCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/DisplayColumnStyleEditorCommandHandler.java
index c804adb8..67b67d2b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/DisplayColumnStyleEditorCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/DisplayColumnStyleEditorCommandHandler.java
@@ -14,27 +14,26 @@
 package org.eclipse.statet.ecommons.waltable.style.editor;
 
 import static org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes.CELL_STYLE;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.style.DisplayMode.NORMAL;
+import static org.eclipse.statet.ecommons.waltable.core.config.DisplayMode.NORMAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Properties;
-import java.util.Set;
 
 import org.eclipse.swt.widgets.Display;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.ILValueIterator;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.jcommons.collections.LongIterator;
+
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
 import org.eclipse.statet.ecommons.waltable.layer.cell.ColumnOverrideLabelAccumulator;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
 import org.eclipse.statet.ecommons.waltable.persistence.StylePersistor;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.Style;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 
 
 /**
@@ -44,18 +43,18 @@ import org.eclipse.statet.ecommons.waltable.style.Style;
  * 3. Applies the label from step 2 to all cells in the selected column
  * 
  */
-public class DisplayColumnStyleEditorCommandHandler extends AbstractLayerCommandHandler<DisplayColumnStyleEditorCommand> implements IPersistable {
+public class DisplayColumnStyleEditorCommandHandler extends AbstractLayerCommandHandler<DisplayColumnStyleEditorCommand> implements Persistable {
 	
 	protected static final String PERSISTENCE_PREFIX= "userDefinedColumnStyle"; //$NON-NLS-1$
 	protected static final String USER_EDITED_STYLE_LABEL= "USER_EDITED_STYLE_FOR_INDEX_"; //$NON-NLS-1$
 
 	protected final SelectionLayer selectionLayer;
 	protected ColumnOverrideLabelAccumulator columnLabelAccumulator;
-	private final IConfigRegistry configRegistry;
+	private final ConfigRegistry configRegistry;
 	protected ColumnStyleEditorDialog dialog;
-	protected final Map<String, Style> stylesToPersist= new HashMap<>();
+	protected final Map<String, BasicStyle> stylesToPersist= new HashMap<>();
 
-	public DisplayColumnStyleEditorCommandHandler(final SelectionLayer selectionLayer, final ColumnOverrideLabelAccumulator labelAccumulator, final IConfigRegistry configRegistry) {
+	public DisplayColumnStyleEditorCommandHandler(final SelectionLayer selectionLayer, final ColumnOverrideLabelAccumulator labelAccumulator, final ConfigRegistry configRegistry) {
 		this.selectionLayer= selectionLayer;
 		this.columnLabelAccumulator= labelAccumulator;
 		this.configRegistry= configRegistry;
@@ -67,11 +66,11 @@ public class DisplayColumnStyleEditorCommandHandler extends AbstractLayerCommand
 				.getPositionId(command.columnPosition, command.columnPosition);
 		
 		final LabelStack configLabels= new LabelStack();
-		this.columnLabelAccumulator.accumulateConfigLabels(configLabels, columnIndexOfClick, 0);
+		this.columnLabelAccumulator.addLabels(configLabels, columnIndexOfClick, 0);
 		configLabels.addLabel(getConfigLabel(columnIndexOfClick));
 		
 		// Column style
-		final Style clickedCellStyle= (Style) this.configRegistry.getConfigAttribute(CELL_STYLE, NORMAL, configLabels.getLabels());
+		final BasicStyle clickedCellStyle= (BasicStyle) this.configRegistry.getAttribute(CELL_STYLE, NORMAL, configLabels.getLabels());
 		
 		this.dialog= new ColumnStyleEditorDialog(Display.getCurrent().getActiveShell(), clickedCellStyle);
 		this.dialog.open();
@@ -91,20 +90,20 @@ public class DisplayColumnStyleEditorCommandHandler extends AbstractLayerCommand
 
 	protected void applySelectedStyleToColumns(final DisplayColumnStyleEditorCommand command,
 			final LRangeList columnPositions) {
-		for (final ILValueIterator columnIter= columnPositions.values().iterator(); columnIter.hasNext(); ) {
+		for (final LongIterator columnIter= columnPositions.values().iterator(); columnIter.hasNext(); ) {
 			final long position= columnIter.nextValue();
 			final long columnIndex= this.selectionLayer.getDim(HORIZONTAL).getPositionId(position, position);
 			// Read the edited styles
-			final Style newColumnCellStyle= this.dialog.getNewColumnCellStyle(); 
+			final BasicStyle newColumnCellStyle= this.dialog.getNewColumnCellStyle(); 
 			
 			final String configLabel= getConfigLabel(columnIndex);
 			if (newColumnCellStyle == null) {
 				this.stylesToPersist.remove(configLabel);
 			} else {
-				newColumnCellStyle.setAttributeValue(CellStyleAttributes.BORDER_STYLE, this.dialog.getNewColumnBorderStyle());
+				newColumnCellStyle.setAttributeValue(CellStyling.BORDER_STYLE, this.dialog.getNewColumnBorderStyle());
 				this.stylesToPersist.put(configLabel, newColumnCellStyle);
 			}
-			this.configRegistry.registerConfigAttribute(CELL_STYLE, newColumnCellStyle, NORMAL, configLabel);
+			this.configRegistry.registerAttribute(CELL_STYLE, newColumnCellStyle, NORMAL, configLabel);
 			this.columnLabelAccumulator.registerColumnOverridesOnTop(columnIndex, configLabel);
 		}
 	}
@@ -114,22 +113,17 @@ public class DisplayColumnStyleEditorCommandHandler extends AbstractLayerCommand
 	}
 
 	@Override
-	public void loadState(String prefix, final Properties properties) {
+	public void loadState(String prefix, final Map<String, String> properties) {
 		prefix= prefix + DOT + PERSISTENCE_PREFIX;
-		final Set<Object> keySet= properties.keySet();
-
-		for (final Object key : keySet) {
-			final String keyString= (String) key;
-
-			// Relevant Key
-			if (keyString.contains(PERSISTENCE_PREFIX)) {
-				final long colIndex= parseColumnIndexFromKey(keyString);
-
+		for (final var entry : properties.entrySet()) {
+			final String key= entry.getKey();
+			if (key.contains(PERSISTENCE_PREFIX)) {
+				final long colIndex= parseColumnIndexFromKey(key);
 				// Has the config label been processed
 				if (!this.stylesToPersist.keySet().contains(getConfigLabel(colIndex))) {
-					final Style savedStyle= StylePersistor.loadStyle(prefix + DOT + getConfigLabel(colIndex), properties);
-
-					this.configRegistry.registerConfigAttribute(CELL_STYLE, savedStyle, NORMAL, getConfigLabel(colIndex));
+					final BasicStyle savedStyle= StylePersistor.loadStyle(prefix + DOT + getConfigLabel(colIndex), properties);
+					
+					this.configRegistry.registerAttribute(CELL_STYLE, savedStyle, NORMAL, getConfigLabel(colIndex));
 					this.stylesToPersist.put(getConfigLabel(colIndex), savedStyle);
 					this.columnLabelAccumulator.registerColumnOverrides(colIndex, getConfigLabel(colIndex));
 				}
@@ -146,11 +140,11 @@ public class DisplayColumnStyleEditorCommandHandler extends AbstractLayerCommand
 	}
 
 	@Override
-	public void saveState(String prefix, final Properties properties) {
+	public void saveState(String prefix, final Map<String, String> properties) {
 		prefix= prefix + DOT + PERSISTENCE_PREFIX;
 
-		for (final Map.Entry<String, Style> labelToStyle : this.stylesToPersist.entrySet()) {
-			final Style style= labelToStyle.getValue();
+		for (final Map.Entry<String, BasicStyle> labelToStyle : this.stylesToPersist.entrySet()) {
+			final BasicStyle style= labelToStyle.getValue();
 			final String label= labelToStyle.getKey();
 
 			StylePersistor.saveStyle(prefix + DOT + label, properties, style);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/GridColorsEditorPanel.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/GridColorsEditorPanel.java
index 96bbb8d1..7f8098d7 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/GridColorsEditorPanel.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/GridColorsEditorPanel.java
@@ -20,7 +20,7 @@ import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Label;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
 
 
 public class GridColorsEditorPanel extends AbstractEditorPanel<GridStyleParameterObject> {
@@ -28,7 +28,7 @@ public class GridColorsEditorPanel extends AbstractEditorPanel<GridStyleParamete
 	private ColorPicker evenRowColorPicker;
 	private ColorPicker oddRowColorPicker;
 	private ColorPicker selectionColorPicker;
-	private IConfigRegistry configRegistry;
+	private ConfigRegistry configRegistry;
 
 	public GridColorsEditorPanel(final Composite parent, final GridStyleParameterObject currentStyle) {
 		super(parent, SWT.NONE);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/GridStyleParameterObject.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/GridStyleParameterObject.java
index a1c82e8b..b55dc835 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/GridStyleParameterObject.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/GridStyleParameterObject.java
@@ -17,11 +17,11 @@ import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.Font;
 
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.grid.cell.AlternatingRowConfigLabelAccumulator;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.grid.AlternatingRowLabelContributor;
 
 
 public class GridStyleParameterObject {
@@ -31,39 +31,39 @@ public class GridStyleParameterObject {
 	public Color oddRowColor;
 	public Color selectionColor;
 
-	public IStyle evenRowStyle;
-	public IStyle oddRowStyle;
-	public IStyle selectionStyle;
-	public IStyle tableStyle;
+	public Style evenRowStyle;
+	public Style oddRowStyle;
+	public Style selectionStyle;
+	public Style tableStyle;
 
-	private final IConfigRegistry configRegistry;
+	private final ConfigRegistry configRegistry;
 
-	public GridStyleParameterObject(final IConfigRegistry configRegistry) {
+	public GridStyleParameterObject(final ConfigRegistry configRegistry) {
 		this.configRegistry= configRegistry;
 		init(configRegistry);
 	}
 
-	private void init(final IConfigRegistry configRegistry) {
-		this.evenRowStyle= configRegistry.getConfigAttribute(
+	private void init(final ConfigRegistry configRegistry) {
+		this.evenRowStyle= configRegistry.getAttribute(
 				CellConfigAttributes.CELL_STYLE, 
 				DisplayMode.NORMAL, 
-				AlternatingRowConfigLabelAccumulator.EVEN_ROW_CONFIG_TYPE);
-		this.evenRowColor= this.evenRowStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
+				AlternatingRowLabelContributor.EVEN_ROW_CONFIG_TYPE);
+		this.evenRowColor= this.evenRowStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR);
 
-		this.oddRowStyle= configRegistry.getConfigAttribute(
+		this.oddRowStyle= configRegistry.getAttribute(
 				CellConfigAttributes.CELL_STYLE, 
 				DisplayMode.NORMAL, 
-				AlternatingRowConfigLabelAccumulator.ODD_ROW_CONFIG_TYPE);
-		this.oddRowColor= this.oddRowStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
+				AlternatingRowLabelContributor.ODD_ROW_CONFIG_TYPE);
+		this.oddRowColor= this.oddRowStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR);
 
-		this.selectionStyle= configRegistry.getConfigAttribute(CellConfigAttributes.CELL_STYLE, DisplayMode.SELECT);
-		this.selectionColor= this.selectionStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
+		this.selectionStyle= configRegistry.getAttribute(CellConfigAttributes.CELL_STYLE, DisplayMode.SELECTED);
+		this.selectionColor= this.selectionStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR);
 		
-		this.tableStyle= configRegistry.getConfigAttribute(CellConfigAttributes.CELL_STYLE, DisplayMode.NORMAL);
-		this.tableFont= this.tableStyle.getAttributeValue(CellStyleAttributes.FONT);
+		this.tableStyle= configRegistry.getAttribute(CellConfigAttributes.CELL_STYLE, DisplayMode.NORMAL);
+		this.tableFont= this.tableStyle.getAttributeValue(CellStyling.FONT);
 	}
 	
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getConfigRegistry() {
 		return this.configRegistry;
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/HorizontalAlignmentPicker.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/HorizontalAlignmentPicker.java
index ce1bd776..9f877d23 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/HorizontalAlignmentPicker.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/HorizontalAlignmentPicker.java
@@ -19,7 +19,7 @@ import org.eclipse.swt.widgets.Combo;
 import org.eclipse.swt.widgets.Composite;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
 
 
 /**
@@ -33,9 +33,12 @@ public class HorizontalAlignmentPicker extends Composite {
         super(parent, SWT.NONE);
         setLayout(new RowLayout());
 
-        this.combo= new Combo(this, SWT.READ_ONLY | SWT.DROP_DOWN);
-        this.combo.setItems(new String[] { Messages.getString("HorizontalAlignmentPicker.center"), Messages.getString("HorizontalAlignmentPicker.left"), Messages.getString("HorizontalAlignmentPicker.right") }); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
-
+		this.combo= new Combo(this, SWT.READ_ONLY | SWT.DROP_DOWN);
+		this.combo.setItems(
+				Messages.getString("HorizontalAlignmentPicker.center"), //$NON-NLS-1$
+				Messages.getString("HorizontalAlignmentPicker.left"), //$NON-NLS-1$
+				Messages.getString("HorizontalAlignmentPicker.right") ); //$NON-NLS-1$
+		
         update(alignment);
     }
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/LineStylePicker.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/LineStylePicker.java
index 67eb0168..ef63788d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/LineStylePicker.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/LineStylePicker.java
@@ -21,7 +21,7 @@ import org.eclipse.swt.widgets.Combo;
 import org.eclipse.swt.widgets.Composite;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle.LineStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle.LineStyle;
 
 
 /**
@@ -35,8 +35,13 @@ public class LineStylePicker extends Composite {
         super(parent, NONE);
         setLayout(new RowLayout());
         
-        this.combo= new Combo(this, SWT.READ_ONLY | SWT.DROP_DOWN);
-        this.combo.setItems(new String[] { Messages.getString("LineStylePicker.solid"), Messages.getString("LineStylePicker.dashed"), Messages.getString("LineStylePicker.dotted"), Messages.getString("LineStylePicker.dashdot"), Messages.getString("LineStylePicker.dashdotdot") }); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
+		this.combo= new Combo(this, SWT.READ_ONLY | SWT.DROP_DOWN);
+		this.combo.setItems(
+				Messages.getString("LineStylePicker.solid"), //$NON-NLS-1$
+				Messages.getString("LineStylePicker.dashed"), //$NON-NLS-1$
+				Messages.getString("LineStylePicker.dotted"), //$NON-NLS-1$
+				Messages.getString("LineStylePicker.dashdot"), //$NON-NLS-1$
+				Messages.getString("LineStylePicker.dashdotdot") ); //$NON-NLS-1$
         this.combo.select(0);
     }
     
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/VerticalAlignmentPicker.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/VerticalAlignmentPicker.java
index ff52d0d2..88e74c0e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/VerticalAlignmentPicker.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/editor/VerticalAlignmentPicker.java
@@ -19,7 +19,7 @@ import org.eclipse.swt.widgets.Combo;
 import org.eclipse.swt.widgets.Composite;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.style.VerticalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.VerticalAlignment;
 
 
 /**
@@ -33,8 +33,11 @@ public class VerticalAlignmentPicker extends Composite {
         super(parent, SWT.NONE);
         setLayout(new RowLayout());
 
-        this.combo= new Combo(this, SWT.READ_ONLY | SWT.DROP_DOWN);
-        this.combo.setItems(new String[] { Messages.getString("VerticalAlignmentPicker.top"), Messages.getString("VerticalAlignmentPicker.middle"), Messages.getString("VerticalAlignmentPicker.bottom") }); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+		this.combo= new Combo(this, SWT.READ_ONLY | SWT.DROP_DOWN);
+		this.combo.setItems(
+				Messages.getString("VerticalAlignmentPicker.top"), //$NON-NLS-1$
+				Messages.getString("VerticalAlignmentPicker.middle"), //$NON-NLS-1$
+				Messages.getString("VerticalAlignmentPicker.bottom") ); //$NON-NLS-1$
 
         update(alignment);
     }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/swt/SWTUtil.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/swt/SWTUtil.java
deleted file mode 100644
index 1d3e4373..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/swt/SWTUtil.java
+++ /dev/null
@@ -1,160 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2013, 2021 Stephan Wahlbrink and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
- # which is available at https://www.apache.org/licenses/LICENSE-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
- # 
- # Contributors:
- #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.swt;
-
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-
-import org.eclipse.swt.SWT;
-import org.eclipse.swt.events.MouseEvent;
-import org.eclipse.swt.graphics.Point;
-import org.eclipse.swt.graphics.Rectangle;
-import org.eclipse.swt.widgets.ScrollBar;
-import org.eclipse.swt.widgets.Scrollable;
-
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle.LineStyle;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
-
-
-public class SWTUtil {
-	
-	
-	public static final int getMouseWheelEventType(/*@NonNull*/ final Orientation orientation) {
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
-		}
-		return (orientation == HORIZONTAL) ?
-				SWT.MouseHorizontalWheel :
-				SWT.MouseVerticalWheel;
-	}
-	
-	public static final ScrollBar getScrollBar(/*@NonNull*/ final Scrollable control,
-			/*@NonNull*/ final Orientation orientation) {
-		if (control == null) {
-			throw new NullPointerException("control"); //$NON-NLS-1$
-		}
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
-		}
-		return (orientation == HORIZONTAL) ?
-				control.getHorizontalBar() :
-				control.getVerticalBar();
-	}
-	
-	public static final LRange getRange(/*@NonNull*/ final LRectangle lRectangle,
-			/*@NonNull*/ final Orientation orientation) {
-		if (lRectangle == null) {
-			throw new NullPointerException("rectangle"); //$NON-NLS-1$
-		}
-		if (orientation == null) {
-			throw new NullPointerException("orientation"); //$NON-NLS-1$
-		}
-		return (orientation == HORIZONTAL) ?
-				new LRange(lRectangle.x, lRectangle.x + lRectangle.width) :
-				new LRange(lRectangle.y, lRectangle.y + lRectangle.height);
-	}
-	
-	
-	public static final int get(final org.eclipse.swt.graphics.Point point, final Orientation orientation) {
-		return (orientation == HORIZONTAL) ?
-				point.x :
-				point.y;
-	}
-	
-	public static final int getStart(final org.eclipse.swt.graphics.Rectangle rect, final Orientation orientation) {
-		return (orientation == HORIZONTAL) ?
-				rect.x :
-				rect.y;
-	}
-	
-	public static final int getEnd(final org.eclipse.swt.graphics.Rectangle rect, final Orientation orientation) {
-		return (orientation == HORIZONTAL) ?
-				rect.x + rect.width :
-				rect.y + rect.height;
-	}
-	
-	public static final int getSize(final org.eclipse.swt.graphics.Rectangle rect, final Orientation orientation) {
-		return (orientation == HORIZONTAL) ?
-				rect.width :
-				rect.height;
-	}
-	
-	public static final int get(final org.eclipse.swt.events.MouseEvent point, final Orientation orientation) {
-		return (orientation == HORIZONTAL) ?
-				point.x :
-				point.y;
-	}
-	
-	
-	public static final Rectangle toSWT(final LRectangle rect) {
-		if (rect.x > Integer.MAX_VALUE || rect.y > Integer.MAX_VALUE
-				|| rect.width > Integer.MAX_VALUE || rect.height > Integer.MAX_VALUE) {
-			throw new IndexOutOfBoundsException();
-		}
-		return new Rectangle((int) rect.x, (int) rect.y, (int) rect.width, (int) rect.height);
-	}
-	
-	public static final LRectangle toNatTable(final Rectangle rect) {
-		return new LRectangle(rect.x, rect.y, rect.width, rect.height);
-	}
-	
-	public static final Point toSWT(final LPoint lPoint) {
-		if (lPoint.x > Integer.MAX_VALUE || lPoint.y > Integer.MAX_VALUE) {
-			throw new IndexOutOfBoundsException();
-		}
-		return new org.eclipse.swt.graphics.Point((int) lPoint.x, (int) lPoint.y);
-	}
-	
-	
-	public static final int getPixel(final MouseEvent event, final Orientation orientation) {
-		return (orientation == HORIZONTAL) ?
-				event.x :
-				event.y;
-	}
-	
-	public static final int toSWT(final HorizontalAlignment alignment) {
-		switch (alignment) {
-		case LEFT:
-			return SWT.LEFT;
-		case CENTER:
-			return SWT.CENTER;
-		case RIGHT:
-			return SWT.RIGHT;
-		default:
-			throw new IllegalStateException();
-		}
-	}
-	
-	public static final int toSWT(final LineStyle lineStyle) {
-		switch (lineStyle) {
-		case SOLID:
-			return SWT.LINE_SOLID;
-		case DASHED:
-			return SWT.LINE_DASH;
-		case DOTTED:
-			return SWT.LINE_DOT;
-		case DASHDOT:
-			return SWT.LINE_DASHDOT;
-		case DASHDOTDOT:
-			return SWT.LINE_DASHDOTDOT;
-		default:
-			throw new IllegalStateException();
-		}
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tooltip/TableContentTooltip.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tooltip/TableContentTooltip.java
index 00e7db75..c049a720 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tooltip/TableContentTooltip.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tooltip/TableContentTooltip.java
@@ -19,14 +19,14 @@ import org.eclipse.swt.widgets.Event;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 import org.eclipse.statet.ecommons.waltable.layer.cell.CellDisplayConversionUtils;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 import org.eclipse.statet.ecommons.waltable.painter.cell.CellPainterWrapper;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.PasswordTextPainter;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
 
 
 /**
@@ -92,15 +92,15 @@ public class TableContentTooltip extends DefaultToolTip {
 		final long col= this.natTable.getColumnPositionByX(event.x);
 		final long row= this.natTable.getRowPositionByY(event.y);
 		
-		final ILayerCell cell= this.natTable.getCellByPosition(col, row);
+		final LayerCell cell= this.natTable.getCellByPosition(col, row);
 		if (cell != null) {
 			//if the registered cell painter is the PasswordCellPainter, there will be no tooltip
-			final ICellPainter painter= this.natTable.getConfigRegistry().getConfigAttribute(
-					CellConfigAttributes.CELL_PAINTER, DisplayMode.NORMAL, cell.getConfigLabels().getLabels());
+			final LayerCellPainter painter= this.natTable.getStyleRegistry().getAttribute(
+					CellConfigAttributes.CELL_PAINTER, DisplayMode.NORMAL, cell.getLabels().getLabels());
 			if (isVisibleContentPainter(painter)) {
 				final String tooltipValue= CellDisplayConversionUtils.convertDataType(
 						cell, 
-						this.natTable.getConfigRegistry());
+						this.natTable.getStyleRegistry());
 				
 				if (tooltipValue.length() > 0) {
 					return tooltipValue;
@@ -111,12 +111,12 @@ public class TableContentTooltip extends DefaultToolTip {
 	}
 	
 	/**
-	 * Checks if the given {@link ICellPainter} is showing the content directly or if it is
+	 * Checks if the given {@link LayerCellPainter} is showing the content directly or if it is
 	 * anonymized by using the {@link PasswordTextPainter}
-	 * @param painter The {@link ICellPainter} to check.
+	 * @param painter The {@link LayerCellPainter} to check.
 	 * @return <code>true</code> if the painter is not a {@link PasswordTextPainter}
 	 */
-	protected boolean isVisibleContentPainter(final ICellPainter painter) {
+	protected boolean isVisibleContentPainter(final LayerCellPainter painter) {
 		if (painter instanceof PasswordTextPainter) {
 			return false;
 		} else if (painter instanceof CellPainterWrapper) {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/NatEventData.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/NatEventData.java
index 226b854b..5eed5f39 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/NatEventData.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/NatEventData.java
@@ -16,7 +16,7 @@ package org.eclipse.statet.ecommons.waltable.ui;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
 
 
 public class NatEventData {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/action/AbstractNavigationAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/action/AbstractNavigationAction.java
index 87ceb5ea..59fb0921 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/action/AbstractNavigationAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/action/AbstractNavigationAction.java
@@ -14,7 +14,7 @@
 
 package org.eclipse.statet.ecommons.waltable.ui.action;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
 
 
 public abstract class AbstractNavigationAction implements IKeyAction {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/action/CellDragMode.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/action/CellDragMode.java
index b797c0a0..2c69c67b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/action/CellDragMode.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/action/CellDragMode.java
@@ -20,12 +20,12 @@ import org.eclipse.swt.graphics.ImageData;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.painter.IOverlayPainter;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.top.OverlayPainter;
 
 
 public class CellDragMode implements IDragMode {
@@ -76,7 +76,7 @@ public class CellDragMode implements IDragMode {
 	private void setCellImage(final NatTable natTable) {
 		final long columnPosition= natTable.getColumnPositionByX(this.currentEvent.x);
 		final long rowPosition= natTable.getRowPositionByY(this.currentEvent.y);
-		final ILayerCell cell= natTable.getCellByPosition(columnPosition, rowPosition);
+		final LayerCell cell= natTable.getCellByPosition(columnPosition, rowPosition);
 		
 		final LRectangle cellBounds= cell.getBounds();
 		final int width= (int) Math.min(cellBounds.width, 0x1fff);
@@ -86,11 +86,11 @@ public class CellDragMode implements IDragMode {
 		final Image image= new Image(natTable.getDisplay(), width, height);
 		
 		final GC gc= new GC(image);
-		final IConfigRegistry configRegistry= natTable.getConfigRegistry();
-		final ICellPainter cellPainter= configRegistry.getConfigAttribute(CellConfigAttributes.CELL_PAINTER,
-				cell.getDisplayMode(), cell.getConfigLabels().getLabels() );
-		if (cellPainter != null) {
-			cellPainter.paintCell(cell, gc, new LRectangle(0, 0, width, height), configRegistry);
+		final ConfigRegistry configRegistry= natTable.getStyleRegistry();
+		final LayerCellPainter layerCellPainter= configRegistry.getAttribute(CellConfigAttributes.CELL_PAINTER,
+				cell.getDisplayMode(), cell.getLabels().getLabels() );
+		if (layerCellPainter != null) {
+			layerCellPainter.paintCell(cell, gc, new LRectangle(0, 0, width, height), configRegistry);
 		}
 		gc.dispose();
 		
@@ -101,10 +101,10 @@ public class CellDragMode implements IDragMode {
 		this.cellImage= new Image(natTable.getDisplay(), imageData);
 	}
 
-	private class CellImageOverlayPainter implements IOverlayPainter {
+	private class CellImageOverlayPainter implements OverlayPainter {
 
 		@Override
-		public void paintOverlay(final GC gc, final ILayer layer) {
+		public void paintOverlay(final GC gc, final Layer layer) {
 			if (CellDragMode.this.cellImage != null & !CellDragMode.this.cellImage.isDisposed()) {
 				gc.drawImage(CellDragMode.this.cellImage, CellDragMode.this.currentEvent.x - CellDragMode.this.xOffset, CellDragMode.this.currentEvent.y - CellDragMode.this.yOffset);
 			}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/binding/UiBindingRegistry.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/binding/UiBindingRegistry.java
index 41b789dc..60ddb589 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/binding/UiBindingRegistry.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/binding/UiBindingRegistry.java
@@ -21,7 +21,7 @@ import org.eclipse.swt.events.KeyEvent;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
 import org.eclipse.statet.ecommons.waltable.ui.action.IDragMode;
 import org.eclipse.statet.ecommons.waltable.ui.action.IKeyAction;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellEditorMouseEventMatcher.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellEditorMouseEventMatcher.java
index f226e1c9..4517876b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellEditorMouseEventMatcher.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellEditorMouseEventMatcher.java
@@ -16,11 +16,11 @@ package org.eclipse.statet.ecommons.waltable.ui.matcher;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 import org.eclipse.statet.ecommons.waltable.edit.editor.ICellEditor;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
 
 
 /**
@@ -96,15 +96,15 @@ public class CellEditorMouseEventMatcher implements IMouseEventMatcher {
 		if ((this.regionLabel == null || (regionLabels != null && regionLabels.hasLabel(this.regionLabel)))
 				&& event.button == this.button) {
 			
-			final ILayerCell cell= natTable.getCellByPosition(
+			final LayerCell cell= natTable.getCellByPosition(
 					natTable.getColumnPositionByX(event.x), 
 					natTable.getRowPositionByY(event.y));
 			
 			//Bug 407598: only perform a check if the click in the body region was performed on a cell
 			//cell == null can happen if the viewport is quite large and contains not enough cells to fill it.
 			if (cell != null) {
-				final ICellEditor cellEditor= natTable.getConfigRegistry().getConfigAttribute(
-						EditConfigAttributes.CELL_EDITOR, DisplayMode.EDIT, cell.getConfigLabels().getLabels());
+				final ICellEditor cellEditor= natTable.getStyleRegistry().getAttribute(
+						EditConfigAttributes.CELL_EDITOR, DisplayMode.EDIT, cell.getLabels().getLabels());
 				
 				if (cellEditor != null && cellEditor.activateAtAnyPosition()) {
 					//if there is a cell editor configured for the cell that was clicked on, the match is found
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellLabelMouseEventMatcher.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellLabelMouseEventMatcher.java
index d327a706..5d3ebcbc 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellLabelMouseEventMatcher.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellLabelMouseEventMatcher.java
@@ -16,8 +16,8 @@ package org.eclipse.statet.ecommons.waltable.ui.matcher;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.ui.NatEventData;
 
 
@@ -44,10 +44,10 @@ public class CellLabelMouseEventMatcher extends MouseEventMatcher {
 	@Override
 	public boolean matches(final NatTable natTable, final MouseEvent event, final LabelStack regionLabels) {
 		final NatEventData eventData= NatEventData.createInstanceFromEvent(event);
-		final ILayerCell cell= natTable.getCellByPosition(eventData.getColumnPosition(), eventData.getRowPosition());
+		final LayerCell cell= natTable.getCellByPosition(eventData.getColumnPosition(), eventData.getRowPosition());
 		return (cell != null
 				&& super.matches(natTable, event, regionLabels)
-				&& cell.getConfigLabels().getLabels().contains(this.labelToMatch) );
+				&& cell.getLabels().getLabels().contains(this.labelToMatch) );
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellPainterMouseEventMatcher.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellPainterMouseEventMatcher.java
index 91e2cbb9..94508bf6 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellPainterMouseEventMatcher.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/CellPainterMouseEventMatcher.java
@@ -18,11 +18,11 @@ import org.eclipse.swt.graphics.GC;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 
 
 /**
@@ -31,16 +31,16 @@ import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
 public class CellPainterMouseEventMatcher extends MouseEventMatcher {
 	
 	
-	private ICellPainter targetCellPainter;
-	private Class<? extends ICellPainter> targetCellPainterClass;
+	private LayerCellPainter targetCellPainter;
+	private Class<? extends LayerCellPainter> targetCellPainterClass;
 	
 	
-	public CellPainterMouseEventMatcher(final String regionName, final int button, final ICellPainter targetCellPainter) {
+	public CellPainterMouseEventMatcher(final String regionName, final int button, final LayerCellPainter targetCellPainter) {
 		super(regionName, button);
 		this.targetCellPainter= targetCellPainter;
 	}
 	
-	public CellPainterMouseEventMatcher(final String regionName, final int button, final Class<? extends ICellPainter> targetCellPainterClass) {
+	public CellPainterMouseEventMatcher(final String regionName, final int button, final Class<? extends LayerCellPainter> targetCellPainterClass) {
 		super(regionName, button);
 		this.targetCellPainterClass= targetCellPainterClass;
 	}
@@ -52,20 +52,20 @@ public class CellPainterMouseEventMatcher extends MouseEventMatcher {
 			final long columnPosition= natTable.getColumnPositionByX(event.x);
 			final long rowPosition= natTable.getRowPositionByY(event.y);
 			
-			final ILayerCell cell= natTable.getCellByPosition(columnPosition, rowPosition);
+			final LayerCell cell= natTable.getCellByPosition(columnPosition, rowPosition);
 			
 			//Bug 407598: only perform a check if the click in the body region was performed on a cell
 			//cell == null can happen if the viewport is quite large and contains not enough cells to fill it.
 			if (cell != null) {
-				final IConfigRegistry configRegistry= natTable.getConfigRegistry();
-				final ICellPainter cellPainter= configRegistry.getConfigAttribute(CellConfigAttributes.CELL_PAINTER,
-						cell.getDisplayMode(), cell.getConfigLabels().getLabels() );
+				final ConfigRegistry configRegistry= natTable.getStyleRegistry();
+				final LayerCellPainter layerCellPainter= configRegistry.getAttribute(CellConfigAttributes.CELL_PAINTER,
+						cell.getDisplayMode(), cell.getLabels().getLabels() );
 				
 				final GC gc= new GC(natTable.getDisplay());
 				try {
 					final LRectangle adjustedCellBounds= natTable.getLayerPainter().adjustCellBounds(columnPosition, rowPosition, cell.getBounds());
 					
-					final ICellPainter clickedCellPainter= cellPainter.getCellPainterAt(event.x, event.y, cell, gc, adjustedCellBounds, configRegistry);
+					final LayerCellPainter clickedCellPainter= layerCellPainter.getCellPainterAt(event.x, event.y, cell, gc, adjustedCellBounds, configRegistry);
 					if (clickedCellPainter != null) {
 						if (	(this.targetCellPainter != null && this.targetCellPainter == clickedCellPainter) ||
 								(this.targetCellPainterClass != null && this.targetCellPainterClass.isInstance(clickedCellPainter))) {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/IMouseEventMatcher.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/IMouseEventMatcher.java
index 2698c4cf..c1127c7f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/IMouseEventMatcher.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/IMouseEventMatcher.java
@@ -16,7 +16,7 @@ package org.eclipse.statet.ecommons.waltable.ui.matcher;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
 
 
 public interface IMouseEventMatcher {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/LetterOrDigitKeyEventMatcher.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/LetterOrDigitKeyEventMatcher.java
index 14667383..7409f225 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/LetterOrDigitKeyEventMatcher.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/LetterOrDigitKeyEventMatcher.java
@@ -79,7 +79,7 @@ public class LetterOrDigitKeyEventMatcher implements IKeyEventMatcher {
 	 */
 	public static boolean isLetterOrDigit(final char character) {
 		return Character.isLetterOrDigit(character)
-				|| Character.valueOf(character).toString().matches(
+				|| Character.toString(character).matches(
 						"[\\.:,;\\-_#\'+*~!?§$%&/()\\[\\]\\{\\}=\\\\\"]"); //$NON-NLS-1$
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/MouseEventMatcher.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/MouseEventMatcher.java
index 2de09320..913a8a7e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/MouseEventMatcher.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/MouseEventMatcher.java
@@ -16,8 +16,8 @@ package org.eclipse.statet.ecommons.waltable.ui.matcher;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 
 
 public class MouseEventMatcher implements IMouseEventMatcher {
@@ -55,7 +55,7 @@ public class MouseEventMatcher implements IMouseEventMatcher {
 	/**
 	 * Constructor
 	 * @param stateMask @see "org.eclipse.swt.events.MouseEvent.stateMask"
-	 * @param eventRegion {@linkplain org.eclipse.statet.ecommons.waltable.grid.GridRegion}
+	 * @param eventRegion {@linkplain org.eclipse.statet.ecommons.waltable.grid.core.GridLabels}
 	 * @param button @see org.eclipse.swt.events.MouseEvent#button
 	 *  	{@link IMouseEventMatcher#LEFT_BUTTON}, {@link IMouseEventMatcher#RIGHT_BUTTON}
 	 *  	can be used for convenience
@@ -119,43 +119,28 @@ public class MouseEventMatcher implements IMouseEventMatcher {
 
 
 	public static MouseEventMatcher columnHeaderLeftClick(final int mask) {
-	    return new MouseEventMatcher(mask, GridRegion.COLUMN_HEADER, LEFT_BUTTON);
+	    return new MouseEventMatcher(mask, GridLabels.COLUMN_HEADER, LEFT_BUTTON);
 	}
 
 	public static MouseEventMatcher columnHeaderRightClick(final int mask) {
-		return new MouseEventMatcher(mask, GridRegion.COLUMN_HEADER, RIGHT_BUTTON);
+		return new MouseEventMatcher(mask, GridLabels.COLUMN_HEADER, RIGHT_BUTTON);
 	}
 
 	public static MouseEventMatcher rowHeaderLeftClick(final int mask) {
-		return new MouseEventMatcher(mask, GridRegion.ROW_HEADER, LEFT_BUTTON);
+		return new MouseEventMatcher(mask, GridLabels.ROW_HEADER, LEFT_BUTTON);
 	}
 	
 	public static MouseEventMatcher rowHeaderRightClick(final int mask) {
-		return new MouseEventMatcher(mask, GridRegion.ROW_HEADER, RIGHT_BUTTON);
+		return new MouseEventMatcher(mask, GridLabels.ROW_HEADER, RIGHT_BUTTON);
 	}
 
 	public static MouseEventMatcher bodyLeftClick(final int mask) {
-		return new MouseEventMatcher(mask, GridRegion.BODY, LEFT_BUTTON);
+		return new MouseEventMatcher(mask, GridLabels.BODY, LEFT_BUTTON);
 	}
 	
 	public static MouseEventMatcher bodyRightClick(final int mask) {
-		return new MouseEventMatcher(mask, GridRegion.BODY, RIGHT_BUTTON);
-	}
-
-	public static MouseEventMatcher columnGroupHeaderLeftClick(final int mask) {
-	    return new MouseEventMatcher(mask, GridRegion.COLUMN_GROUP_HEADER, LEFT_BUTTON);
-	}
-	
-	public static MouseEventMatcher columnGroupHeaderRightClick(final int mask) {
-	    return new MouseEventMatcher(mask, GridRegion.COLUMN_GROUP_HEADER, RIGHT_BUTTON);
+		return new MouseEventMatcher(mask, GridLabels.BODY, RIGHT_BUTTON);
 	}
 	
-	public static MouseEventMatcher rowGroupHeaderLeftClick(final int mask) {
-	    return new MouseEventMatcher(mask, GridRegion.ROW_GROUP_HEADER, LEFT_BUTTON);
-	}
-
-	public static MouseEventMatcher rowGroupHeaderRightClick(final int mask) {
-	    return new MouseEventMatcher(mask, GridRegion.ROW_GROUP_HEADER, RIGHT_BUTTON);
-	}
 }
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/AbstractHeaderMenuConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/AbstractHeaderMenuConfiguration.java
index 41ef0841..15a975c3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/AbstractHeaderMenuConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/AbstractHeaderMenuConfiguration.java
@@ -20,7 +20,7 @@ import org.eclipse.swt.widgets.Menu;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
 import org.eclipse.statet.ecommons.waltable.config.AbstractUiBindingConfiguration;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.MouseEventMatcher;
 
@@ -116,19 +116,19 @@ public class AbstractHeaderMenuConfiguration extends AbstractUiBindingConfigurat
 	public void configureUiBindings(final UiBindingRegistry uiBindingRegistry) {
 		if (this.colHeaderMenu != null) {
 			uiBindingRegistry.registerMouseDownBinding(
-					new MouseEventMatcher(SWT.NONE, GridRegion.COLUMN_HEADER, MouseEventMatcher.RIGHT_BUTTON),
+					new MouseEventMatcher(SWT.NONE, GridLabels.COLUMN_HEADER, MouseEventMatcher.RIGHT_BUTTON),
 					new PopupMenuAction(this.colHeaderMenu));
 		}
 
 		if (this.rowHeaderMenu != null) {
 			uiBindingRegistry.registerMouseDownBinding(
-					new MouseEventMatcher(SWT.NONE, GridRegion.ROW_HEADER, MouseEventMatcher.RIGHT_BUTTON),
+					new MouseEventMatcher(SWT.NONE, GridLabels.ROW_HEADER, MouseEventMatcher.RIGHT_BUTTON),
 					new PopupMenuAction(this.rowHeaderMenu));
 		}
 
 		if (this.cornerMenu != null) {
 			uiBindingRegistry.registerMouseDownBinding(
-					new MouseEventMatcher(SWT.NONE, GridRegion.CORNER, MouseEventMatcher.RIGHT_BUTTON),
+					new MouseEventMatcher(SWT.NONE, GridLabels.CORNER, MouseEventMatcher.RIGHT_BUTTON),
 					new PopupMenuAction(this.cornerMenu));
 		}
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/BodyMenuConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/BodyMenuConfiguration.java
index 9a6b9d94..1f05185f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/BodyMenuConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/BodyMenuConfiguration.java
@@ -21,8 +21,8 @@ import org.eclipse.swt.widgets.Menu;
 import org.eclipse.statet.ecommons.waltable.Messages;
 import org.eclipse.statet.ecommons.waltable.NatTable;
 import org.eclipse.statet.ecommons.waltable.config.AbstractUiBindingConfiguration;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.MouseEventMatcher;
 
@@ -31,7 +31,7 @@ public class BodyMenuConfiguration extends AbstractUiBindingConfiguration {
 
 	private final Menu colHeaderMenu;
 	
-	public BodyMenuConfiguration(final NatTable natTable, final ILayer bodyLayer) {
+	public BodyMenuConfiguration(final NatTable natTable, final Layer bodyLayer) {
 		this.colHeaderMenu= new PopupMenuBuilder(natTable)
 								.withColumnStyleEditor(Messages.getString("ColumnStyleEditorDialog.shellTitle")) //$NON-NLS-1$
 								.build();
@@ -49,7 +49,7 @@ public class BodyMenuConfiguration extends AbstractUiBindingConfiguration {
 	@Override
 	public void configureUiBindings(final UiBindingRegistry uiBindingRegistry) {
 		uiBindingRegistry.registerMouseDownBinding(
-				new MouseEventMatcher(SWT.NONE, GridRegion.COLUMN_HEADER, 3), 
+				new MouseEventMatcher(SWT.NONE, GridLabels.COLUMN_HEADER, 3), 
 				new PopupMenuAction(this.colHeaderMenu));
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/MenuItemProviders.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/MenuItemProviders.java
index 37eaa319..d4cb89d2 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/MenuItemProviders.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/menu/MenuItemProviders.java
@@ -13,8 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.ui.menu;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.SelectionAdapter;
@@ -26,10 +26,9 @@ import org.eclipse.swt.widgets.Widget;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.persistence.DisplayPersistenceDialogCommand;
-import org.eclipse.statet.ecommons.waltable.resize.InitializeAutoResizeCommand;
+import org.eclipse.statet.ecommons.waltable.resize.core.InitializeAutoResizeCommand;
 import org.eclipse.statet.ecommons.waltable.style.editor.DisplayColumnStyleEditorCommand;
 import org.eclipse.statet.ecommons.waltable.ui.NatEventData;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
@@ -165,7 +164,7 @@ public class MenuItemProviders {
 					public void widgetSelected(final SelectionEvent event) {
 						final long rowPosition= getNatEventData(event).getRowPosition();
 						final long columnPosition= getNatEventData(event).getColumnPosition();
-						natTable.doCommand(new DisplayColumnStyleEditorCommand(natTable, natTable.getConfigRegistry(), columnPosition, rowPosition));
+						natTable.doCommand(new DisplayColumnStyleEditorCommand(natTable, natTable.getStyleRegistry(), columnPosition, rowPosition));
 					}
 				});
 			}
@@ -190,15 +189,15 @@ public class MenuItemProviders {
 						final long columnPosition= natEventData.getColumnPosition();
 						final long rowPosition= natEventData.getRowPosition();
 						
-						final ILayerCell cell= natTable.getCellByPosition(columnPosition, rowPosition);
+						final LayerCell cell= natTable.getCellByPosition(columnPosition, rowPosition);
 						
 						final String msg= "Display mode: " + cell.getDisplayMode() + //$NON-NLS-1$
-								"\nConfig labels: " + cell.getConfigLabels() + //$NON-NLS-1$
+								"\nConfig labels: " + cell.getLabels() + //$NON-NLS-1$
 								"\nData value: " + cell.getDataValue(0, null) + //$NON-NLS-1$
 								"\n\nColumn position: " + columnPosition + //$NON-NLS-1$
-								"\nColumn id: " + cell.getDim(Orientation.HORIZONTAL).getId() + //$NON-NLS-1$
+								"\nColumn id: " + cell.getDim(HORIZONTAL).getId() + //$NON-NLS-1$
 								"\n\nRow position: " + rowPosition + //$NON-NLS-1$
-								"\nRow id: " + cell.getDim(Orientation.VERTICAL).getId(); //$NON-NLS-1$
+								"\nRow id: " + cell.getDim(VERTICAL).getId(); //$NON-NLS-1$
 
 						final MessageBox messageBox= new MessageBox(natTable.getShell(), SWT.ICON_INFORMATION | SWT.OK);
 						messageBox.setText(Messages.getString("MenuItemProviders.debugInformation")); //$NON-NLS-1$
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/widget/NatCombo.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/swt/widgets/NatCombo.java
index 1ec70143..c3c2f8d7 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/widget/NatCombo.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/swt/widgets/NatCombo.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.widget;
+package org.eclipse.statet.ecommons.waltable.ui.swt.widgets;
 
 import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
 
@@ -54,11 +54,11 @@ import org.eclipse.swt.widgets.Table;
 import org.eclipse.swt.widgets.TableItem;
 import org.eclipse.swt.widgets.Text;
 
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.HorizontalAlignment;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.style.VerticalAlignment;
 import org.eclipse.statet.ecommons.waltable.style.CellStyleUtil;
-import org.eclipse.statet.ecommons.waltable.style.HorizontalAlignment;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
-import org.eclipse.statet.ecommons.waltable.style.VerticalAlignment;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.LetterOrDigitKeyEventMatcher;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
@@ -105,7 +105,7 @@ public class NatCombo extends Composite {
 	 * The important configurations used are horizontal alignment, background and 
 	 * foreground color and font.
 	 */
-	protected final IStyle cellStyle;
+	protected final Style cellStyle;
 
 	/**
 	 * The maximum number of visible items of the combo.
@@ -215,7 +215,7 @@ public class NatCombo extends Composite {
 	 * @param style The style for the Text Control to construct. Uses this style
 	 * 			adding internal styles via ConfigRegistry.
 	 */
-	public NatCombo(final Composite parent, final IStyle cellStyle, final int style) {
+	public NatCombo(final Composite parent, final Style cellStyle, final int style) {
 		this(parent, cellStyle, DEFAULT_NUM_OF_VISIBLE_ITEMS, style, GUIHelper.getImage("down_2")); //$NON-NLS-1$
 	}
 
@@ -231,7 +231,7 @@ public class NatCombo extends Composite {
 	 * @param style The style for the Text Control to construct. Uses this style
 	 * 			adding internal styles via ConfigRegistry.
 	 */
-	public NatCombo(final Composite parent, final IStyle cellStyle, final int maxVisibleItems, final int style) {
+	public NatCombo(final Composite parent, final Style cellStyle, final int maxVisibleItems, final int style) {
 		this(parent, cellStyle, maxVisibleItems, style, GUIHelper.getImage("down_2")); //$NON-NLS-1$
 	}
 
@@ -249,7 +249,7 @@ public class NatCombo extends Composite {
 	 * 			is visible. Using this image will indicate that the control is an open combo
 	 * 			to the user.
 	 */
-	public NatCombo(final Composite parent, final IStyle cellStyle, final int maxVisibleItems, final int style, final Image iconImage) {
+	public NatCombo(final Composite parent, final Style cellStyle, final int maxVisibleItems, final int style, final Image iconImage) {
 		super(parent, SWT.NONE);
 
 		this.cellStyle= cellStyle;
@@ -304,9 +304,9 @@ public class NatCombo extends Composite {
 	protected void createTextControl(final int style) {
 		final int widgetStyle= style | CellStyleUtil.getHorizontalAlignmentSWT(this.cellStyle, SWT.NONE);
 		this.text= new Text(this, widgetStyle);
-		this.text.setBackground(this.cellStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR));
-		this.text.setForeground(this.cellStyle.getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR));
-		this.text.setFont(this.cellStyle.getAttributeValue(CellStyleAttributes.FONT));
+		this.text.setBackground(this.cellStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR));
+		this.text.setForeground(this.cellStyle.getAttributeValue(CellStyling.FOREGROUND_COLOR));
+		this.text.setFont(this.cellStyle.getAttributeValue(CellStyling.FONT));
 
 		GridData gridData= new GridData(SWT.FILL, SWT.FILL, true, true);
 		this.text.setLayoutData(gridData);
@@ -434,9 +434,9 @@ public class NatCombo extends Composite {
 				| CellStyleUtil.getHorizontalAlignmentSWT(this.cellStyle, SWT.NONE);
 
 		this.dropdownTable= new Table(this.dropdownShell, dropdownListStyle);
-		this.dropdownTable.setBackground(this.cellStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR));
-		this.dropdownTable.setForeground(this.cellStyle.getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR));
-		this.dropdownTable.setFont(this.cellStyle.getAttributeValue(CellStyleAttributes.FONT));
+		this.dropdownTable.setBackground(this.cellStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR));
+		this.dropdownTable.setForeground(this.cellStyle.getAttributeValue(CellStyling.FOREGROUND_COLOR));
+		this.dropdownTable.setFont(this.cellStyle.getAttributeValue(CellStyling.FONT));
 		
 		this.dropdownTable.addSelectionListener(new SelectionAdapter() {
 			@Override
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/util/CellEdgeDetectUtil.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/util/CellEdgeDetectUtil.java
index e4b877bb..df8e5a45 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/util/CellEdgeDetectUtil.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/util/CellEdgeDetectUtil.java
@@ -13,8 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.ui.util;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 import static org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeEnum.BOTTOM;
 import static org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeEnum.LEFT;
 import static org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeEnum.NONE;
@@ -22,11 +22,11 @@ import static org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeEnum.RIGHT;
 import static org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeEnum.TOP;
 import static org.eclipse.statet.ecommons.waltable.util.GUIHelper.DEFAULT_RESIZE_HANDLE_SIZE;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 public class CellEdgeDetectUtil {
@@ -37,9 +37,9 @@ public class CellEdgeDetectUtil {
 	 * on the left/right edges of the cell.
 	 * Does <i>not</i> take into account columns which are not allowed to be resized.
 	 */
-	public static long getPositionToResize(final ILayer layer, final LPoint clickPoint,
+	public static long getPositionToResize(final Layer layer, final LPoint clickPoint,
 			final Orientation orientation) {
-		final ILayerCell cell= layer.getCellByPosition(
+		final LayerCell cell= layer.getCellByPosition(
 				layer.getDim(HORIZONTAL).getPositionByPixel(clickPoint.x), 
 				layer.getDim(VERTICAL).getPositionByPixel(clickPoint.y) );
 		if (cell != null) {
@@ -65,13 +65,13 @@ public class CellEdgeDetectUtil {
 	}
 	
 	
-	public static CellEdgeEnum getHorizontalCellEdge(final ILayer layer, final LPoint clickPt) {
+	public static CellEdgeEnum getHorizontalCellEdge(final Layer layer, final LPoint clickPt) {
 		return getHorizontalCellEdge(layer, clickPt, -1);
 	}
 	
-	public static CellEdgeEnum getHorizontalCellEdge(final ILayer layer, final LPoint clickPt,
+	public static CellEdgeEnum getHorizontalCellEdge(final Layer layer, final LPoint clickPt,
 			final long handleWidth) {
-		final ILayerCell cell= layer.getCellByPosition(
+		final LayerCell cell= layer.getCellByPosition(
 				layer.getColumnPositionByX(clickPt.x),
 				layer.getRowPositionByY(clickPt.y) );
 		
@@ -108,13 +108,13 @@ public class CellEdgeDetectUtil {
 	}
 	
 	
-	public static CellEdgeEnum getVerticalCellEdge(final ILayer layer, final LPoint clickPt) {
+	public static CellEdgeEnum getVerticalCellEdge(final Layer layer, final LPoint clickPt) {
 		return getVerticalCellEdge(layer, clickPt, -1);
 	}
 	
-	public static CellEdgeEnum getVerticalCellEdge(final ILayer layer, final LPoint clickPt,
+	public static CellEdgeEnum getVerticalCellEdge(final Layer layer, final LPoint clickPt,
 			final long handleHeight) {
-		final ILayerCell cell= layer.getCellByPosition(
+		final LayerCell cell= layer.getCellByPosition(
 				layer.getColumnPositionByX(clickPt.x),
 				layer.getRowPositionByY(clickPt.y) );
 		
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/util/ComparatorChain.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/util/ComparatorChain.java
deleted file mode 100644
index 86dda67e..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/util/ComparatorChain.java
+++ /dev/null
@@ -1,39 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.util;
-
-import java.util.Comparator;
-import java.util.List;
-
-
-public class ComparatorChain<T> implements Comparator<T> {
-
-	private final List<Comparator<T>> comparators;
-
-	public ComparatorChain(final List<Comparator<T>> comparators) {
-		this.comparators= comparators;
-	}
-	
-	@Override
-	public int compare(final T arg0, final T arg1) {
-		for (int i= 0; i < this.comparators.size(); i++) {
-			final int compareResult= this.comparators.get(i).compare(arg0, arg1);
-			if (compareResult != 0) {
-				return compareResult;
-			}
-		}
-		return 0;
-	}
-
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/util/GUIHelper.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/util/GUIHelper.java
index 80cd72b4..5474e42c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/util/GUIHelper.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/util/GUIHelper.java
@@ -56,28 +56,10 @@ public class GUIHelper {
 	public static final Color COLOR_WIDGET_NORMAL_SHADOW= Display.getDefault().getSystemColor(SWT.COLOR_WIDGET_NORMAL_SHADOW);
 	public static final Color COLOR_WIDGET_HIGHLIGHT_SHADOW= Display.getDefault().getSystemColor( SWT.COLOR_WIDGET_HIGHLIGHT_SHADOW);
 
-	public static Color getColor(final RGB rgb) {
-		return getColor(rgb.red, rgb.green, rgb.blue);
-	}
-
-	public static Color getColor(final int red, final int green, final int blue) {
-		final String key= getColorKey(red, green, blue);
-		if (JFaceResources.getColorRegistry().hasValueFor(key)) {
-			return JFaceResources.getColorRegistry().get(key);
-		} else {
-			JFaceResources.getColorRegistry().put(key, new RGB(red, green, blue));
-			return getColor(key);
-		}
-	}
-
 	public static Color getColor(final String key) {
 		return JFaceResources.getColorRegistry().get(key);
 	}
 
-	private static String getColorKey(final int red, final int green, final int blue) {
-		return KEY_PREFIX + "_COLOR_" + red + "_" + green + "_" + blue; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
-	}
-
 	// Font
 
 	public static final Font DEFAULT_FONT= Display.getDefault().getSystemFont();
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollEvent.java
deleted file mode 100644
index 44fb0dec..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollEvent.java
+++ /dev/null
@@ -1,49 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.viewport;
-
-import java.util.Collection;
-
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralRefreshEvent;
-
-
-public class ScrollEvent extends StructuralRefreshEvent {
-
-	public ScrollEvent(final ViewportLayer viewportLayer) {
-		super(viewportLayer);
-	}
-	
-	protected ScrollEvent(final ScrollEvent event) {
-		super(event);
-	}
-	
-	@Override
-	public ScrollEvent cloneEvent() {
-		return new ScrollEvent(this);
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getColumnDiffs() {
-		// TODO this is bogus - should have a horiz/vert scroll event instead that are multi col/row structural changes
-		return null;
-	}
-	
-	@Override
-	public Collection<StructuralDiff> getRowDiffs() {
-		// TODO this is bogus - should have a horiz/vert scroll event instead that are multi col/row structural changes
-		return null;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/SelectRelativePageCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/SelectRelativePageCommandHandler.java
deleted file mode 100644
index ef633774..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/SelectRelativePageCommandHandler.java
+++ /dev/null
@@ -1,60 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2010, 2021 Stephan Wahlbrink and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
- # which is available at https://www.apache.org/licenses/LICENSE-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
- # 
- # Contributors:
- #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.viewport;
-
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.selection.SelectRelativeCellCommand;
-
-
-public class SelectRelativePageCommandHandler extends AbstractLayerCommandHandler<SelectRelativePageCommand> {
-	
-	
-	private final ILayer viewportLayer;
-	
-	
-	public SelectRelativePageCommandHandler(final ILayer viewportLayer) {
-		this.viewportLayer= viewportLayer;
-	}
-	
-	
-	@Override
-	public Class<SelectRelativePageCommand> getCommandClass() {
-		return SelectRelativePageCommand.class;
-	}
-	
-	@Override
-	protected boolean doCommand(final SelectRelativePageCommand command) {
-		if (command.convertToTargetLayer(this.viewportLayer)) {
-			long stepCount;
-			switch (command.getDirection()) {
-			case UP:
-			case DOWN:
-				stepCount= this.viewportLayer.getRowCount();
-				break;
-			case LEFT:
-			case RIGHT:
-				stepCount= this.viewportLayer.getColumnCount();
-				break;
-			default:
-				return false;
-			}
-			this.viewportLayer.doCommand(new SelectRelativeCellCommand(
-					command.getDirection(), stepCount, command.getSelectionFlags() ));
-		}
-		return true;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/widget/WaitDialog.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/widget/WaitDialog.java
deleted file mode 100644
index 11900d2c..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/widget/WaitDialog.java
+++ /dev/null
@@ -1,90 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2012, 2021 Original NatTable authors and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     Original NatTable authors and others - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.ecommons.waltable.widget;
-
-import static org.eclipse.swt.layout.GridData.CENTER;
-
-import org.eclipse.jface.dialogs.Dialog;
-import org.eclipse.swt.SWT;
-import org.eclipse.swt.graphics.FontData;
-import org.eclipse.swt.graphics.Image;
-import org.eclipse.swt.layout.GridData;
-import org.eclipse.swt.layout.GridLayout;
-import org.eclipse.swt.widgets.Composite;
-import org.eclipse.swt.widgets.Control;
-import org.eclipse.swt.widgets.Label;
-import org.eclipse.swt.widgets.Shell;
-
-import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
-
-
-public class WaitDialog extends Dialog {
-
-	private String msg;
-	private final Image iconImage;
-	private Label textLabel;
-
-	public WaitDialog(final Shell parent, final int shellStyle, final String msg, final Image iconImg) {
-		super(parent);
-		this.msg= msg;
-		this.iconImage= iconImg;
-		setShellStyle(shellStyle | SWT.APPLICATION_MODAL);
-	}
-
-	private void centerDialogOnScreen(final Shell shell) {
-		shell.setSize(250, 75);
-		final org.eclipse.swt.graphics.Rectangle parentSize= getParentShell().getBounds();
-		final org.eclipse.swt.graphics.Rectangle mySize= shell.getBounds();
-		int locationX, locationY;
-		locationX= (parentSize.width - mySize.width)/2+parentSize.x;
-		locationY= (parentSize.height - mySize.height)/2+parentSize.y;
-		shell.setLocation(locationX, locationY);
-	}
-
-	@Override
-	protected Control createContents(final Composite parent) {
-		centerDialogOnScreen(getShell());
-		
-		final Composite composite= new Composite(parent, SWT.NONE);
-		composite.setLayout(new GridLayout(2, false));
-		composite.setLayoutData(new GridData(CENTER, CENTER, true, true));
-		composite.setRedraw(true);
-
-		final Label imgLabel= new Label(composite, SWT.NONE);
-		imgLabel.setImage(this.iconImage);
-		
-		this.textLabel= new Label(composite, SWT.NONE);
-		this.textLabel.setLayoutData(new GridData(CENTER, CENTER, true, true));
-		this.textLabel.setFont(GUIHelper.getFont(new FontData("Arial", 9, SWT.BOLD))); //$NON-NLS-1$
-		this.textLabel.setRedraw(true);
-		this.textLabel.setText(this.msg);
-
-		return composite;
-	}
-
-	public void setMsg(final String msg) {
-		this.msg= msg;
-		this.textLabel.setText(msg);
-		getShell().layout(new Control[]{this.textLabel});
-	}
-
-	@Override
-	public boolean close() {
-		if (this.iconImage != null) {
-			this.iconImage.dispose();
-		}
-		return super.close();
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/internal/ecommons/waltable/LayerListenerList.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/internal/ecommons/waltable/LayerListenerList.java
deleted file mode 100644
index bb7801f4..00000000
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/internal/ecommons/waltable/LayerListenerList.java
+++ /dev/null
@@ -1,173 +0,0 @@
-/*=============================================================================#
- # Copyright (c) 2004, 2021 IBM Corporation and others.
- # 
- # This program and the accompanying materials are made available under the
- # terms of the Eclipse Public License 2.0 which is available at
- # https://www.eclipse.org/legal/epl-2.0.
- # 
- # SPDX-License-Identifier: EPL-2.0
- # 
- # Contributors:
- #     IBM Corporation - org.eclipse.platform: initial API and implementation
- #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
- #=============================================================================*/
-
-package org.eclipse.statet.internal.ecommons.waltable;
-
-import org.eclipse.statet.ecommons.waltable.layer.ILayerListener;
-
-
-/**
- * This class is a thread safe list that is designed for storing lists of listeners.
- * The implementation is optimized for minimal memory footprint, frequent reads 
- * and infrequent writes.  Modification of the list is synchronized and relatively
- * expensive, while accessing the listeners is very fast.  Readers are given access 
- * to the underlying array data structure for reading, with the trust that they will 
- * not modify the underlying array.
- * <p>
- * <a name="same">A listener list handles the <i>same</i> listener being added 
- * multiple times, and tolerates removal of listeners that are the same as other
- * listeners in the list.  For this purpose, listeners can be compared with each other 
- * using either equality or identity, as specified in the list constructor.
- * </p>
- * <p>
- * Use the <code>getListeners</code> method when notifying listeners. The recommended
- * code sequence for notifying all registered listeners of say,
- * <code>FooListener.eventHappened</code>, is:
- * 
- * <pre>
- * Object[] listeners= myListenerList.getListeners();
- * for (int i= 0; i &lt; listeners.length; ++i) {
- * 	((FooListener) listeners[i]).eventHappened(event);
- * }
- * </pre>
- * 
- * </p><p>
- * This class can be used without OSGi running.
- * </p>
- * @since org.eclipse.equinox.common 3.2
- */
-public class LayerListenerList {
-	
-	/**
-	 * The empty array singleton instance.
-	 */
-	private static final ILayerListener[] EMPTY_ARRAY= new ILayerListener[0];
-	
-	
-	/**
-	 * The list of listeners.  Initially empty but initialized
-	 * to an array of size capacity the first time a listener is added.
-	 * Maintains invariant: listeners != null
-	 */
-	private volatile ILayerListener[] listeners= EMPTY_ARRAY;
-	
-	/**
-	 * Creates a listener list.
-	 */
-	public LayerListenerList() {
-	}
-	
-	
-	/**
-	 * Adds a listener to this list. This method has no effect if the <a href="#same">same</a>
-	 * listener is already registered.
-	 * 
-	 * @param listener the non-<code>null</code> listener to add
-	 */
-	public synchronized void add(final ILayerListener listener) {
-		// This method is synchronized to protect against multiple threads adding 
-		// or removing listeners concurrently. This does not block concurrent readers.
-		if (listener == null) {
-			throw new IllegalArgumentException();
-		}
-		// check for duplicates 
-		final int oldSize= this.listeners.length;
-		for (int i= 0; i < oldSize; ++i) {
-			final ILayerListener listener2= this.listeners[i];
-			if (listener == listener2) {
-				return;
-			}
-		}
-		// Thread safety: create new array to avoid affecting concurrent readers
-		final ILayerListener[] newListeners= new ILayerListener[oldSize + 1];
-		System.arraycopy(this.listeners, 0, newListeners, 0, oldSize);
-		newListeners[oldSize]= listener;
-		//atomic assignment
-		this.listeners= newListeners;
-	}
-	
-	/**
-	 * Returns an array containing all the registered listeners.
-	 * The resulting array is unaffected by subsequent adds or removes.
-	 * If there are no listeners registered, the result is an empty array.
-	 * Use this method when notifying listeners, so that any modifications
-	 * to the listener list during the notification will have no effect on 
-	 * the notification itself.
-	 * <p>
-	 * Note: Callers of this method <b>must not</b> modify the returned array. 
-	 *
-	 * @return the list of registered listeners
-	 */
-	public ILayerListener[] getListeners() {
-		return this.listeners;
-	}
-	
-	/**
-	 * Returns whether this listener list is empty.
-	 *
-	 * @return <code>true</code> if there are no registered listeners, and
-	 *   <code>false</code> otherwise
-	 */
-	public boolean isEmpty() {
-		return this.listeners.length == 0;
-	}
-	
-	/**
-	 * Removes a listener from this list. Has no effect if the <a href="#same">same</a> 
-	 * listener was not already registered.
-	 *
-	 * @param listener the non-<code>null</code> listener to remove
-	 */
-	public synchronized void remove(final Object listener) {
-		// This method is synchronized to protect against multiple threads adding 
-		// or removing listeners concurrently. This does not block concurrent readers.
-		if (listener == null) {
-			throw new IllegalArgumentException();
-		}
-		final int oldSize= this.listeners.length;
-		for (int i= 0; i < oldSize; ++i) {
-			final ILayerListener listener2= this.listeners[i];
-			if (listener == listener2) {
-				if (oldSize == 1) {
-					this.listeners= EMPTY_ARRAY;
-				} else {
-					// Thread safety: create new array to avoid affecting concurrent readers
-					final ILayerListener[] newListeners= new ILayerListener[oldSize - 1];
-					System.arraycopy(this.listeners, 0, newListeners, 0, i);
-					System.arraycopy(this.listeners, i + 1, newListeners, i, oldSize - i - 1);
-					//atomic assignment to field
-					this.listeners= newListeners;
-				}
-				return;
-			}
-		}
-	}
-	
-	/**
-	 * Returns the number of registered listeners.
-	 *
-	 * @return the number of registered listeners
-	 */
-	public long size() {
-		return this.listeners.length;
-	}
-	
-	/**
-	 * Removes all listeners from this list.
-	 */
-	public synchronized void clear() {
-		this.listeners= EMPTY_ARRAY;
-	}
-	
-}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/copy/CopyToClipboardCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/copy/CopyToClipboardCommand.java
index f99f5b90..e855b459 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/copy/CopyToClipboardCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/copy/CopyToClipboardCommand.java
@@ -13,8 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.copy;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
 
 
 public class CopyToClipboardCommand extends AbstractContextFreeCommand {
@@ -22,10 +22,10 @@ public class CopyToClipboardCommand extends AbstractContextFreeCommand {
 	
 	private final String cellDelimeter;
 	private final String rowDelimeter;
-	private final IConfigRegistry configRegistry;
+	private final ConfigRegistry configRegistry;
 	
 	
-	public CopyToClipboardCommand(final String cellDelimeter, final String rowDelimeter, final IConfigRegistry configRegistry) {
+	public CopyToClipboardCommand(final String cellDelimeter, final String rowDelimeter, final ConfigRegistry configRegistry) {
 		this.cellDelimeter= cellDelimeter;
 		this.rowDelimeter= rowDelimeter;
 		this.configRegistry= configRegistry;
@@ -40,7 +40,7 @@ public class CopyToClipboardCommand extends AbstractContextFreeCommand {
 		return this.rowDelimeter;
 	}
 	
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getConfigRegistry() {
 		return this.configRegistry;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/copy/CopyToClipboardCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/copy/CopyToClipboardCommandHandler.java
index 67cfb6e9..66a77a1d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/copy/CopyToClipboardCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/copy/CopyToClipboardCommandHandler.java
@@ -25,15 +25,16 @@ import org.eclipse.swt.dnd.TextTransfer;
 import org.eclipse.swt.dnd.Transfer;
 import org.eclipse.swt.widgets.Display;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.ILValueIterator;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.data.ControlData;
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.collections.LongIterator;
+
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.data.ControlData;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.layer.cell.CellDisplayConversionUtils;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 import org.eclipse.statet.ecommons.waltable.ui.ITableUIContext;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
@@ -57,12 +58,12 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 	/**
 	 * The column header layer of the grid, needed to also copy the column header data.
 	 */
-	private final ILayer columnHeaderDataLayer;
+	private final Layer columnHeaderDataLayer;
 	
 	/**
 	 * The row header layer of the grid, needed to also copy the row header data.
 	 */
-	private final ILayer rowHeaderDataLayer;
+	private final Layer rowHeaderDataLayer;
 	
 	private final ITableUIContext uiContext;
 	
@@ -84,7 +85,7 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 	 * @param rowHeaderDataLayer The row header data layer within the NatTable grid. Can be <code>null</code>.
 	 */
 	public CopyToClipboardCommandHandler(final SelectionLayer selectionLayer,
-			final ILayer columnHeaderDataLayer, final ILayer rowHeaderDataLayer,
+			final Layer columnHeaderDataLayer, final Layer rowHeaderDataLayer,
 			final ITableUIContext uiContext) {
 		if (selectionLayer == null) {
 			throw new NullPointerException("selectionLayer"); //$NON-NLS-1$
@@ -107,7 +108,7 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 	}
 	
 	private void doCopy(final CopyToClipboardCommand command) {
-		final ILayerCell[][] copiedCells= assembleCopiedDataStructure();
+		final LayerCell[][] copiedCells= assembleCopiedDataStructure();
 		if (copiedCells.length == 0) {
 			return;
 		}
@@ -119,7 +120,7 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 			if (rowCount <= 1000 && colCount <= 1000) {
 				for (int rowIdx= 0; rowIdx < rowCount; rowIdx++) {
 					for (int colIdx= 0; colIdx < colCount; colIdx++) {
-						final ILayerCell cell= copiedCells[rowIdx][colIdx];
+						final LayerCell cell= copiedCells[rowIdx][colIdx];
 						if (cell != null) {
 							final Object dataValue= cell.getDataValue(0, null);
 							if (dataValue instanceof ControlData) {
@@ -161,7 +162,7 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 			final StringBuilder textBuilder= new StringBuilder();
 			for (int rowIdx= 0; rowIdx < rowCount; ) {
 				for (int colIdx= 0; colIdx < colCount; ) {
-					final ILayerCell cell= copiedCells[rowIdx][colIdx];
+					final LayerCell cell= copiedCells[rowIdx][colIdx];
 					if (cell != null) {
 						textBuilder.append(getTextForCell(command, cell, values[rowIdx][colIdx]));
 					}
@@ -189,7 +190,7 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 		}
 	}
 	
-	private void loadAsync(final ILayerCell[][] copiedCells, final Object[][] values,
+	private void loadAsync(final LayerCell[][] copiedCells, final Object[][] values,
 			final int startRowIdx, final int startColIdx) throws CoreException {
 		try {
 			this.uiContext.run(true, true, new IRunnableWithProgress() {
@@ -204,9 +205,9 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 						
 						for (int rowIdx= startRowIdx; rowIdx < rowCount; rowIdx++) {
 							for (int colIdx= (rowIdx == startRowIdx) ? startColIdx : 0; colIdx < colCount; colIdx++) {
-								final ILayerCell cell= copiedCells[rowIdx][colIdx];
+								final LayerCell cell= copiedCells[rowIdx][colIdx];
 								if (cell != null) {
-									final Object dataValue= cell.getDataValue(IDataProvider.FORCE_SYNC,
+									final Object dataValue= cell.getDataValue(DataProvider.FORCE_SYNC,
 											monitor );
 									if (dataValue instanceof ControlData) {
 										if ((((ControlData) dataValue).getCode() & ControlData.ERROR) != 0) {
@@ -249,7 +250,7 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 		}
 	}
 	
-	protected String getTextForCell(final CopyToClipboardCommand command, final ILayerCell cell, final Object value) {
+	protected String getTextForCell(final CopyToClipboardCommand command, final LayerCell cell, final Object value) {
 		return CellDisplayConversionUtils.convertDataType(cell, value, command.getConfigRegistry());
 	}
 	
@@ -269,7 +270,7 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 	 * 			The first level of this array represent the row positions of the cells, while the
 	 * 			second level contains the cells itself based on the column position.
 	 */
-	protected ILayerCell[][] assembleCopiedDataStructure() {
+	protected LayerCell[][] assembleCopiedDataStructure() {
 		final LRangeList selectedRowPositions= this.selectionLayer.getSelectedRowPositions();
 		final LRangeList selectedColumnPositions= this.selectionLayer.getSelectedColumnPositions();
 		
@@ -280,13 +281,13 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 			throw new UnsupportedOperationException("Selected area too large.");
 		}
 		
-		final ILayerCell[][] cells= new ILayerCell[(int) (selectedRowPositions.values().size() + rowOffset)][];
+		final LayerCell[][] cells= new LayerCell[(int) (selectedRowPositions.values().size() + rowOffset)][];
 		
 		int cellsIdx= 0;
 		while (cellsIdx < rowOffset) {
 			cells[cellsIdx++]= assembleColumnHeader(selectedColumnPositions, (int) columnOffset, cellsIdx);
 		}
-		for (final ILValueIterator rowIter= selectedRowPositions.values().iterator(); rowIter.hasNext(); ) {
+		for (final LongIterator rowIter= selectedRowPositions.values().iterator(); rowIter.hasNext(); ) {
 			final long rowPosition= rowIter.nextValue();
 			cells[cellsIdx++]= assembleBody(selectedColumnPositions, (int) columnOffset, rowPosition);
 		}
@@ -304,13 +305,13 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 	 * @param headerRowPosition The row position in the column header of which the information should be collected
 	 * @return An array containing the column header information
 	 */
-	protected ILayerCell[] assembleColumnHeader(final LRangeList selectedColumnPositions, final int columnOffset,
+	protected LayerCell[] assembleColumnHeader(final LRangeList selectedColumnPositions, final int columnOffset,
 			final long headerRowPosition) {
-		final ILayerCell[] headerCells= new ILayerCell[(int) (selectedColumnPositions.values().size() + columnOffset)];
+		final LayerCell[] headerCells= new LayerCell[(int) (selectedColumnPositions.values().size() + columnOffset)];
 		
 		int headerIdx= columnOffset;
 		if (this.columnHeaderDataLayer != null) {
-			for (final ILValueIterator columnIter= selectedColumnPositions.values().iterator(); columnIter.hasNext(); headerIdx++) {
+			for (final LongIterator columnIter= selectedColumnPositions.values().iterator(); columnIter.hasNext(); headerIdx++) {
 				final long columnPosition= columnIter.nextValue();
 				headerCells[headerIdx]= this.columnHeaderDataLayer.getCellByPosition(columnPosition, headerRowPosition);
 			}
@@ -329,9 +330,9 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 	 * @param currentRowPosition The row position of which the selected cells should be collected
 	 * @return An array containing the specified cells
 	 */
-	protected ILayerCell[] assembleBody(final LRangeList selectedColumnPositions,  final int columnOffset,
+	protected LayerCell[] assembleBody(final LRangeList selectedColumnPositions,  final int columnOffset,
 			final long currentRowPosition) {
-		final ILayerCell[] bodyCells= new ILayerCell[(int) (selectedColumnPositions.values().size() + columnOffset)];
+		final LayerCell[] bodyCells= new LayerCell[(int) (selectedColumnPositions.values().size() + columnOffset)];
 		
 		int bodyIdx= 0;
 		if (this.rowHeaderDataLayer != null) {
@@ -339,7 +340,7 @@ public class CopyToClipboardCommandHandler extends AbstractLayerCommandHandler<C
 				bodyCells[bodyIdx]= this.rowHeaderDataLayer.getCellByPosition(bodyIdx, currentRowPosition);
 			}
 		}
-		for (final ILValueIterator columnIter= selectedColumnPositions.values().iterator(); columnIter.hasNext(); bodyIdx++) {
+		for (final LongIterator columnIter= selectedColumnPositions.values().iterator(); columnIter.hasNext(); bodyIdx++) {
 			final long columnPosition= columnIter.nextValue();
 			if (this.selectionLayer.isCellPositionSelected(columnPosition, currentRowPosition)) {
 				bodyCells[bodyIdx]= this.selectionLayer.getCellByPosition(columnPosition, currentRowPosition);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/copy/action/CopyDataAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/copy/ui/action/CopyDataAction.java
index 1be54aa8..183f2ab0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/copy/action/CopyDataAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/copy/ui/action/CopyDataAction.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.copy.action;
+package org.eclipse.statet.ecommons.waltable.copy.ui.action;
 
 import org.eclipse.swt.events.KeyEvent;
 
@@ -29,8 +29,8 @@ public class CopyDataAction implements IKeyAction {
 	
 	@Override
 	public void run(final NatTable natTable, final KeyEvent event) {
-		natTable.doCommand(new CopyToClipboardCommand("\t", System.getProperty("line.separator"), //$NON-NLS-1$ //$NON-NLS-2$
-				natTable.getConfigRegistry() ));
+		natTable.doCommand(new CopyToClipboardCommand("\t", System.lineSeparator(), //$NON-NLS-1$
+		natTable.getStyleRegistry() ));
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/ExportCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ExportCommand.java
index d0fc412a..f43b616c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/ExportCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ExportCommand.java
@@ -15,21 +15,21 @@ package org.eclipse.statet.ecommons.waltable.export;
 
 import org.eclipse.swt.widgets.Shell;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
 
 
 public class ExportCommand extends AbstractContextFreeCommand {
 
-	private final IConfigRegistry configRegistry;
+	private final ConfigRegistry configRegistry;
 	private final Shell shell;
 
-	public ExportCommand(final IConfigRegistry configRegistry, final Shell shell) {
+	public ExportCommand(final ConfigRegistry configRegistry, final Shell shell) {
 		this.configRegistry= configRegistry;
 		this.shell= shell;
 	}
 
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getConfigRegistry() {
 		return this.configRegistry;
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/ExportCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ExportCommandHandler.java
index 149c48e6..142bc753 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/ExportCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ExportCommandHandler.java
@@ -15,32 +15,39 @@ package org.eclipse.statet.ecommons.waltable.export;
 
 import org.eclipse.swt.widgets.Shell;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
-public class ExportCommandHandler extends AbstractLayerCommandHandler<ExportCommand> {
 
-	private final ILayer layer;
-
-	public ExportCommandHandler(final ILayer layer) {
+@NonNullByDefault
+public class ExportCommandHandler implements LayerCommandHandler<ExportCommand> {
+	
+	
+	private final Layer layer;
+	
+	
+	public ExportCommandHandler(final Layer layer) {
 		this.layer= layer;
 	}
-
+	
+	
+	@Override
+	public Class<ExportCommand> getCommandClass() {
+		return ExportCommand.class;
+	}
+	
+	
 	@Override
-	public boolean doCommand(final ExportCommand command) {
+	public boolean executeCommand(final ExportCommand command) {
 		final Shell shell= command.getShell();
-		final IConfigRegistry configRegistry= command.getConfigRegistry();
+		final ConfigRegistry configRegistry= command.getConfigRegistry();
 		
 		new NatExporter(shell).exportSingleLayer(this.layer, configRegistry);
 		
 		return true;
 	}
-
-	@Override
-	public Class<ExportCommand> getCommandClass() {
-		return ExportCommand.class;
-	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/ExportConfigAttributes.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ExportConfigAttributes.java
index e39bbdfb..14d6b1c1 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/ExportConfigAttributes.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ExportConfigAttributes.java
@@ -12,7 +12,7 @@
  #=============================================================================*/ 
 package org.eclipse.statet.ecommons.waltable.export;
 
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/FileOutputStreamProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/FileOutputStreamProvider.java
index f4f055ec..f4f055ec 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/FileOutputStreamProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/FileOutputStreamProvider.java
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/IExportFormatter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/IExportFormatter.java
index dd071452..c3d7fc63 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/IExportFormatter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/IExportFormatter.java
@@ -13,12 +13,12 @@
 
 package org.eclipse.statet.ecommons.waltable.export;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 public interface IExportFormatter {
 
-	Object formatForExport(ILayerCell cell, IConfigRegistry configRegistry);
+	Object formatForExport(LayerCell cell, ConfigRegistry configRegistry);
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/ILayerExporter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ILayerExporter.java
index e29539b9..ff3a7d7c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/ILayerExporter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ILayerExporter.java
@@ -18,8 +18,8 @@ import java.io.OutputStream;
 
 import org.eclipse.swt.widgets.Shell;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 /**
@@ -137,6 +137,6 @@ public interface ILayerExporter {
 	 * 			of the cell that is currently exported.
 	 * @throws IOException If an error occurred during writing the export.
 	 */
-	void exportCell(OutputStream outputStream, Object exportDisplayValue, ILayerCell cell, IConfigRegistry configRegistry) throws IOException;
+	void exportCell(OutputStream outputStream, Object exportDisplayValue, LayerCell cell, ConfigRegistry configRegistry) throws IOException;
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/IOutputStreamProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/IOutputStreamProvider.java
index c558feaf..c558feaf 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/IOutputStreamProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/IOutputStreamProvider.java
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/NatExporter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/NatExporter.java
index 49855817..a8a5f51d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/NatExporter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/NatExporter.java
@@ -25,15 +25,15 @@ import org.eclipse.swt.widgets.Shell;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.ClientAreaProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.print.PrintEntireGridCommand;
 import org.eclipse.statet.ecommons.waltable.print.TurnViewportOffCommand;
 import org.eclipse.statet.ecommons.waltable.print.TurnViewportOnCommand;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.ui.IClientAreaProvider;
 
 
 public class NatExporter {
@@ -50,8 +50,8 @@ public class NatExporter {
 	 * @param configRegistry The ConfigRegistry of the NatTable instance to export,
 	 * 			that contains the necessary export configurations.
 	 */
-	public void exportSingleLayer(final ILayer layer, final IConfigRegistry configRegistry) {
-		final ILayerExporter exporter= configRegistry.getConfigAttribute(ExportConfigAttributes.EXPORTER, DisplayMode.NORMAL);
+	public void exportSingleLayer(final Layer layer, final ConfigRegistry configRegistry) {
+		final ILayerExporter exporter= configRegistry.getAttribute(ExportConfigAttributes.EXPORTER, DisplayMode.NORMAL);
 		
 		final OutputStream outputStream= exporter.getOutputStream(this.shell);
 		if (outputStream == null) {
@@ -109,7 +109,7 @@ public class NatExporter {
 					
 					for (final String name : natTablesMap.keySet()) {
 						final NatTable natTable= natTablesMap.get(name);
-						exportLayer(exporter, outputStream, name, natTable, natTable.getConfigRegistry());
+						exportLayer(exporter, outputStream, name, natTable, natTable.getStyleRegistry());
 					}
 					
 					exporter.exportEnd(outputStream);
@@ -146,8 +146,8 @@ public class NatExporter {
 	 * @param layer
 	 * @param configRegistry
 	 */
-	protected void exportLayer(final ILayerExporter exporter, final OutputStream outputStream, final String layerName, final ILayer layer, final IConfigRegistry configRegistry) {
-		final IClientAreaProvider originalClientAreaProvider= layer.getClientAreaProvider();
+	protected void exportLayer(final ILayerExporter exporter, final OutputStream outputStream, final String layerName, final Layer layer, final ConfigRegistry configRegistry) {
+		final ClientAreaProvider originalClientAreaProvider= layer.getClientAreaProvider();
 		
 		// This needs to be done so that the layer can return all the cells
 		// not just the ones visible in the viewport
@@ -188,9 +188,9 @@ public class NatExporter {
 				}
 				
 				for (long columnPosition= 0; columnPosition < layer.getColumnCount(); columnPosition++) {
-					final ILayerCell cell= layer.getCellByPosition(columnPosition, rowPosition);
+					final LayerCell cell= layer.getCellByPosition(columnPosition, rowPosition);
 					
-					final IExportFormatter exportFormatter= configRegistry.getConfigAttribute(ExportConfigAttributes.EXPORT_FORMATTER, cell.getDisplayMode(), cell.getConfigLabels().getLabels());
+					final IExportFormatter exportFormatter= configRegistry.getAttribute(ExportConfigAttributes.EXPORT_FORMATTER, cell.getDisplayMode(), cell.getLabels().getLabels());
 					final Object exportDisplayValue= exportFormatter.formatForExport(cell, configRegistry);
 
 					exporter.exportCell(outputStream, exportDisplayValue, cell, configRegistry);
@@ -215,10 +215,10 @@ public class NatExporter {
 		}
 	}
 	
-	private void setClientAreaToMaximum(final ILayer layer) {
+	private void setClientAreaToMaximum(final Layer layer) {
 		final LRectangle maxClientArea= new LRectangle(0, 0, layer.getWidth(), layer.getHeight());
 		
-		layer.setClientAreaProvider(new IClientAreaProvider() {
+		layer.setClientAreaProvider(new ClientAreaProvider() {
 			@Override
 			public LRectangle getClientArea() {
 				return maxClientArea;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/config/DefaultExportBindings.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/config/DefaultExportBindings.java
index d41e7b1d..4ed679f3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/config/DefaultExportBindings.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/config/DefaultExportBindings.java
@@ -15,13 +15,13 @@ package org.eclipse.statet.ecommons.waltable.export.config;
 
 import org.eclipse.swt.SWT;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.config.IConfiguration;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 import org.eclipse.statet.ecommons.waltable.export.ExportConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.export.action.ExportAction;
 import org.eclipse.statet.ecommons.waltable.export.excel.DefaultExportFormatter;
 import org.eclipse.statet.ecommons.waltable.export.excel.ExcelExporter;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.export.ui.action.ExportAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.KeyEventMatcher;
 
@@ -34,17 +34,17 @@ public class DefaultExportBindings implements IConfiguration {
 	}
 
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
-		configRegistry.registerConfigAttribute(
+	public void configureRegistry(final ConfigRegistry configRegistry) {
+		configRegistry.registerAttribute(
 				ExportConfigAttributes.EXPORTER, new ExcelExporter());
-		configRegistry.registerConfigAttribute(
+		configRegistry.registerAttribute(
 				ExportConfigAttributes.EXPORT_FORMATTER, new DefaultExportFormatter());
-		configRegistry.registerConfigAttribute(
+		configRegistry.registerAttribute(
 				ExportConfigAttributes.DATE_FORMAT, "m/d/yy h:mm"); //$NON-NLS-1$
 	}
 
 	@Override
-	public void configureLayer(final ILayer layer) {
+	public void configureLayer(final Layer layer) {
 	}
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/excel/DefaultExportFormatter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/excel/DefaultExportFormatter.java
index 984cad9c..10835735 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/excel/DefaultExportFormatter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/excel/DefaultExportFormatter.java
@@ -14,18 +14,18 @@
 package org.eclipse.statet.ecommons.waltable.export.excel;
 
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.data.convert.IDisplayConverter;
 import org.eclipse.statet.ecommons.waltable.export.IExportFormatter;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 
 
 public class DefaultExportFormatter implements IExportFormatter {
 
 	@Override
-	public Object formatForExport(final ILayerCell cell, final IConfigRegistry configRegistry) {
+	public Object formatForExport(final LayerCell cell, final ConfigRegistry configRegistry) {
 		final Object dataValue= cell.getDataValue(0, null);
-		final IDisplayConverter displayConverter= configRegistry.getConfigAttribute(CellConfigAttributes.DISPLAY_CONVERTER, cell.getDisplayMode(), cell.getConfigLabels().getLabels());
+		final IDisplayConverter displayConverter= configRegistry.getAttribute(CellConfigAttributes.DISPLAY_CONVERTER, cell.getDisplayMode(), cell.getLabels().getLabels());
 		return displayConverter.canonicalToDisplayValue(cell, configRegistry, dataValue);
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/excel/ExcelExporter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/excel/ExcelExporter.java
index 7fd57099..10a3220d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/excel/ExcelExporter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/excel/ExcelExporter.java
@@ -24,14 +24,15 @@ import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.graphics.FontData;
 import org.eclipse.swt.widgets.Shell;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.RegistryStyle;
 import org.eclipse.statet.ecommons.waltable.export.FileOutputStreamProvider;
 import org.eclipse.statet.ecommons.waltable.export.ILayerExporter;
 import org.eclipse.statet.ecommons.waltable.export.IOutputStreamProvider;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleProxy;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
@@ -92,9 +93,7 @@ public class ExcelExporter implements ILayerExporter {
 	 * 			the header content file
 	 */
 	private void writeHeader(final OutputStream outputStream) throws IOException {
-		InputStream headerStream= null;
-		try {
-			headerStream= this.getClass().getResourceAsStream(EXCEL_HEADER_FILE);
+		try (InputStream headerStream= this.getClass().getResourceAsStream(EXCEL_HEADER_FILE)) {
 			int c;
 			while ((c= headerStream.read()) != -1) {
 				outputStream.write(c);
@@ -102,10 +101,6 @@ public class ExcelExporter implements ILayerExporter {
 		} catch (final Exception e) {
 			WaLTablePlugin.log(new Status(IStatus.ERROR, WaLTablePlugin.BUNDLE_ID,
 					"Excel Exporter failed: " + e.getMessage(), e)); //$NON-NLS-1$
-		} finally {
-			if (headerStream != null) {
-				headerStream.close();
-			}
 		}
 	}
 
@@ -125,11 +120,12 @@ public class ExcelExporter implements ILayerExporter {
 	}
 
 	@Override
-	public void exportCell(final OutputStream outputStream, final Object exportDisplayValue, final ILayerCell cell, final IConfigRegistry configRegistry) throws IOException {
-		final CellStyleProxy cellStyle= new CellStyleProxy(configRegistry, DisplayMode.NORMAL, cell.getConfigLabels().getLabels());
-		final Color fg= cellStyle.getAttributeValue(CellStyleAttributes.FOREGROUND_COLOR);
-		final Color bg= cellStyle.getAttributeValue(CellStyleAttributes.BACKGROUND_COLOR);
-		final Font font= cellStyle.getAttributeValue(CellStyleAttributes.FONT);
+	public void exportCell(final OutputStream outputStream, final Object exportDisplayValue, final LayerCell cell, final ConfigRegistry configRegistry) throws IOException {
+		final var cellStyle= new RegistryStyle(configRegistry, CellConfigAttributes.CELL_STYLE,
+				DisplayMode.NORMAL, cell.getLabels().getLabels() );
+		final Color fg= cellStyle.getAttributeValue(CellStyling.FOREGROUND_COLOR);
+		final Color bg= cellStyle.getAttributeValue(CellStyling.BACKGROUND_COLOR);
+		final Font font= cellStyle.getAttributeValue(CellStyling.FONT);
 
 		String htmlAttributes= String.format("style='color: %s; background-color: %s; %s;'", //$NON-NLS-1$
 		                     getColorInCSSFormat(fg),
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/excel/excelExportHeader.txt b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/excel/excelExportHeader.txt
index f92e23a2..f92e23a2 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/excel/excelExportHeader.txt
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/excel/excelExportHeader.txt
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/action/ExportAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ui/action/ExportAction.java
index 6edd3ec6..6cae1c51 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/action/ExportAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/export/ui/action/ExportAction.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.export.action;
+package org.eclipse.statet.ecommons.waltable.export.ui.action;
 
 import org.eclipse.swt.events.KeyEvent;
 
@@ -24,7 +24,7 @@ public class ExportAction implements IKeyAction {
 
 	@Override
 	public void run(final NatTable natTable, final KeyEvent event) {
-		natTable.doCommand(new ExportCommand(natTable.getConfigRegistry(), natTable.getShell()));
+		natTable.doCommand(new ExportCommand(natTable.getStyleRegistry(), natTable.getShell()));
 	}
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeCellPositionCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeCellPositionCommand.java
index d6827d49..367d8ffb 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeCellPositionCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeCellPositionCommand.java
@@ -14,8 +14,8 @@
 package org.eclipse.statet.ecommons.waltable.freeze;
 
 import org.eclipse.statet.ecommons.waltable.command.AbstractPositionCommand;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 /**
@@ -45,7 +45,7 @@ public class FreezeCellPositionCommand extends AbstractPositionCommand implement
 	 * @param rowPosition The row position that will be the bottom
 	 * 			row in the frozen part.
 	 */
-	public FreezeCellPositionCommand(final ILayer layer, final long columnPosition, final long rowPosition) {
+	public FreezeCellPositionCommand(final Layer layer, final long columnPosition, final long rowPosition) {
 		this(layer, columnPosition, rowPosition, false);
 	}
 	
@@ -61,7 +61,7 @@ public class FreezeCellPositionCommand extends AbstractPositionCommand implement
 	 * @param toggle whether this command should toggle the frozen state between
 	 * 			frozen and unfrozen, or if it should always result in a frozen state.
 	 */
-	public FreezeCellPositionCommand(final ILayer layer, final long columnPosition, final long rowPosition, final boolean toggle) {
+	public FreezeCellPositionCommand(final Layer layer, final long columnPosition, final long rowPosition, final boolean toggle) {
 		this(layer, columnPosition, rowPosition, toggle, false);
 	}
 	
@@ -78,7 +78,7 @@ public class FreezeCellPositionCommand extends AbstractPositionCommand implement
 	 * @param overrideFreeze whether this command should override a current frozen state
 	 * 			or if it should be skipped if a frozen state is already applied.
 	 */
-	public FreezeCellPositionCommand(final ILayer layer, final long columnPosition, final long rowPosition, final boolean toggle, final boolean overrideFreeze) {
+	public FreezeCellPositionCommand(final Layer layer, final long columnPosition, final long rowPosition, final boolean toggle, final boolean overrideFreeze) {
 		super(layer, columnPosition, rowPosition);
 		this.toggle= toggle;
 		this.overrideFreeze= overrideFreeze;
@@ -106,7 +106,7 @@ public class FreezeCellPositionCommand extends AbstractPositionCommand implement
 	}
 	
 	@Override
-	public ILayerCommand cloneCommand() {
+	public LayerCommand cloneCommand() {
 		return new FreezeCellPositionCommand(this);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeColumnStrategy.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeColumnStrategy.java
index 53fa55b6..53fa55b6 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeColumnStrategy.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeColumnStrategy.java
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeCommandHandler.java
index 98d099aa..80cede81 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeCommandHandler.java
@@ -13,12 +13,12 @@
 
 package org.eclipse.statet.ecommons.waltable.freeze;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
-import org.eclipse.statet.ecommons.waltable.viewport.ViewportLayer;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.viewport.core.ViewportLayer;
 
 
 public class FreezeCommandHandler extends AbstractLayerCommandHandler<IFreezeCommand> {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeDimPositionCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeDimPositionCommand.java
index 29ddaf20..56e4cba6 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeDimPositionCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeDimPositionCommand.java
@@ -13,9 +13,9 @@
 
 package org.eclipse.statet.ecommons.waltable.freeze;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionCommand;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
 
 
 /**
@@ -43,7 +43,7 @@ public class FreezeDimPositionCommand extends AbstractDimPositionCommand impleme
 	 * @param position The column/row position that will be the right most
 	 * 			column/row in the frozen part.
 	 */
-	public FreezeDimPositionCommand(final ILayerDim layerDim, final long position) {
+	public FreezeDimPositionCommand(final LayerDim layerDim, final long position) {
 		this(layerDim, position, false);
 	}
 	
@@ -57,7 +57,7 @@ public class FreezeDimPositionCommand extends AbstractDimPositionCommand impleme
 	 * @param toggle whether this command should toggle the frozen state between
 	 * 			frozen and unfrozen, or if it should always result in a frozen state.
 	 */
-	public FreezeDimPositionCommand(final ILayerDim layerDim, final long position,
+	public FreezeDimPositionCommand(final LayerDim layerDim, final long position,
 			final boolean toggle) {
 		this(layerDim, position, toggle, false);
 	}
@@ -73,7 +73,7 @@ public class FreezeDimPositionCommand extends AbstractDimPositionCommand impleme
 	 * @param overrideFreeze whether this command should override a current frozen state
 	 * 			or if it should be skipped if a frozen state is already applied.
 	 */
-	public FreezeDimPositionCommand(final ILayerDim layerDim, final long position,
+	public FreezeDimPositionCommand(final LayerDim layerDim, final long position,
 			final boolean toggle, final boolean overrideFreeze) {
 		super(layerDim, position);
 		
@@ -104,7 +104,7 @@ public class FreezeDimPositionCommand extends AbstractDimPositionCommand impleme
 	}
 	
 	@Override
-	public ILayerCommand cloneCommand() {
+	public LayerCommand cloneCommand() {
 		return new FreezeDimPositionCommand(this);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeEventHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeEventHandler.java
new file mode 100644
index 00000000..0389d3e6
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeEventHandler.java
@@ -0,0 +1,134 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.freeze;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import java.util.Collection;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerListener;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralChangeEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralDiff;
+
+
+@NonNullByDefault
+public class FreezeEventHandler implements LayerListener {
+	
+	
+	private final FreezeLayer freezeLayer;
+	
+	
+	public FreezeEventHandler(final FreezeLayer freezeLayer) {
+		this.freezeLayer= freezeLayer;
+	}
+	
+	
+	@Override
+	public void handleLayerEvent(final LayerEvent event) {
+		if (event instanceof StructuralChangeEvent) {
+			final var changeEvent= (StructuralChangeEvent)event;
+			final PositionCoordinate topLeftPosition= this.freezeLayer.getTopLeftPosition();
+			final PositionCoordinate bottomRightPosition= this.freezeLayer.getBottomRightPosition();
+			
+			// The handling of diffs have to be in sync with ViewportLayerDim#handleStructuralChanges
+			final Collection<StructuralDiff> columnDiffs= changeEvent.getDiffs(HORIZONTAL);
+			if (columnDiffs != null) {
+				int leftOffset= 0;
+				int rightOffset= 0;
+				int freezeMove= 0; // 0= unset, 1 == true, -1 == false
+				
+				for (final StructuralDiff diff : columnDiffs) {
+					final long start= diff.getBeforePositionRange().start;
+					switch (diff.getDiffType()) {
+					case ADD:
+						if (start < topLeftPosition.columnPosition) {
+							leftOffset+= diff.getAfterPositionRange().size();
+						}
+						if (start <= bottomRightPosition.columnPosition
+								|| (freezeMove == 1 && start == bottomRightPosition.columnPosition + 1) ) {
+							rightOffset+= diff.getAfterPositionRange().size();
+						}
+						continue;
+					case DELETE:
+						if (start < topLeftPosition.columnPosition) {
+							leftOffset-= Math.min(diff.getBeforePositionRange().end, topLeftPosition.columnPosition + 1) - start;
+						}
+						if (start <= bottomRightPosition.columnPosition) {
+							rightOffset-= Math.min(diff.getBeforePositionRange().end, bottomRightPosition.columnPosition + 1) - start;
+							if (freezeMove == 0) {
+								freezeMove= 1;
+							}
+						}
+						else {
+							freezeMove= -1;
+						}
+						continue;
+					default:
+						continue;
+					}
+				}
+				
+				topLeftPosition.columnPosition+= leftOffset;
+				bottomRightPosition.columnPosition+= rightOffset;
+			}
+			
+			final Collection<StructuralDiff> rowDiffs= changeEvent.getDiffs(VERTICAL);
+			if (rowDiffs != null) {
+				int leftOffset= 0;
+				int rightOffset= 0;
+				int freezeMove= 0; // 0= unset, 1 == true, -1 == false
+				
+				for (final StructuralDiff diff : rowDiffs) {
+					final long start= diff.getBeforePositionRange().start;
+					switch (diff.getDiffType()) {
+					case ADD:
+						if (start < topLeftPosition.rowPosition) {
+							leftOffset+= diff.getAfterPositionRange().size();
+						}
+						if (start <= bottomRightPosition.rowPosition
+								|| (freezeMove == 1 && start == bottomRightPosition.rowPosition + 1) ) {
+							rightOffset+= diff.getAfterPositionRange().size();
+						}
+						continue;
+					case DELETE:
+						if (start < topLeftPosition.rowPosition) {
+							leftOffset-= Math.min(diff.getBeforePositionRange().end, topLeftPosition.rowPosition + 1) - start;
+						}
+						if (start <= bottomRightPosition.rowPosition) {
+							rightOffset-= Math.min(diff.getBeforePositionRange().end, bottomRightPosition.rowPosition + 1) - start;
+							if (freezeMove == 0) {
+								freezeMove= 1;
+							}
+						}
+						else {
+							freezeMove= -1;
+						}
+						continue;
+					default:
+						continue;
+					}
+				}
+				
+				topLeftPosition.rowPosition+= leftOffset;
+				bottomRightPosition.rowPosition+= rightOffset;
+			}
+		}
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeHelper.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeHelper.java
index 055b5f93..3dca1601 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeHelper.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeHelper.java
@@ -13,13 +13,15 @@
 
 package org.eclipse.statet.ecommons.waltable.freeze;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
 import org.eclipse.statet.ecommons.waltable.freeze.FreezeLayer.Dim;
-import org.eclipse.statet.ecommons.waltable.viewport.ViewportLayer;
+import org.eclipse.statet.ecommons.waltable.freeze.core.FreezeEvent;
+import org.eclipse.statet.ecommons.waltable.freeze.core.UnfreezeEvent;
+import org.eclipse.statet.ecommons.waltable.viewport.core.ViewportLayer;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeLayer.java
index 1557b6c3..c603fda3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeLayer.java
@@ -13,19 +13,22 @@
 
 package org.eclipse.statet.ecommons.waltable.freeze;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.TransformLayer;
-import org.eclipse.statet.ecommons.waltable.layer.TransformLayerDim;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.TransformLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.TransformLayerDim;
 
 
-public class FreezeLayer extends TransformLayer {
+@NonNullByDefault
+public class FreezeLayer extends TransformLayer<TransformLayerDim<FreezeLayer>> {
 	
 	
 	public static final String PERSISTENCE_TOP_LEFT_POSITION= ".freezeTopLeftPosition"; //$NON-NLS-1$
@@ -39,7 +42,7 @@ public class FreezeLayer extends TransformLayer {
 		private long endPosition;
 		
 		
-		public Dim(final FreezeLayer layer, final ILayerDim underlyingDim) {
+		public Dim(final FreezeLayer layer, final LayerDim underlyingDim) {
 			super(layer, underlyingDim);
 		}
 		
@@ -118,30 +121,28 @@ public class FreezeLayer extends TransformLayer {
 	}
 	
 	
-	public FreezeLayer(final ILayer underlyingLayer) {
+	public FreezeLayer(final Layer underlyingLayer) {
 		super(underlyingLayer);
 		
+		init();
+		
 		registerEventHandler(new FreezeEventHandler(this));
 	}
 	
-	
 	@Override
-	protected void initDims() {
-		final ILayer underlying= getUnderlyingLayer();
-		if (underlying == null) {
-			return;
-		}
-		setDim(new Dim(this, underlying.getDim(HORIZONTAL)));
-		setDim(new Dim(this, underlying.getDim(VERTICAL)));
+	protected Dim createDim(final Orientation orientation) {
+		final Layer underlyingLayer= getUnderlyingLayer();
+		return new Dim(this, underlyingLayer.getDim(orientation));
 	}
 	
+	
 	final Dim get(final Orientation orientation) {
-		return (Dim) getDim(orientation);
+		return (Dim)getDim(orientation);
 	}
 	
 	
 	public boolean isFrozen() {
-		return getColumnCount() > 0 || getRowCount() > 0;
+		return (getColumnCount() > 0 || getRowCount() > 0);
 	}
 	
 	public PositionCoordinate getTopLeftPosition() {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezePositionStrategy.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezePositionStrategy.java
index c8cbd6b5..c8cbd6b5 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezePositionStrategy.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezePositionStrategy.java
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeRowStrategy.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeRowStrategy.java
index 51c03ec8..51c03ec8 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeRowStrategy.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeRowStrategy.java
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeSelectionCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeSelectionCommand.java
index 849c31d6..4c04fc9f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeSelectionCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeSelectionCommand.java
@@ -13,7 +13,7 @@
 
 package org.eclipse.statet.ecommons.waltable.freeze;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 /**
@@ -79,7 +79,7 @@ public class FreezeSelectionCommand implements IFreezeCommand {
 	}
 	
 	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
+	public boolean convertToTargetLayer(final Layer targetLayer) {
 		return true;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeSelectionStrategy.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeSelectionStrategy.java
index 3e79d716..04fe2516 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/FreezeSelectionStrategy.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/FreezeSelectionStrategy.java
@@ -13,14 +13,13 @@
 
 package org.eclipse.statet.ecommons.waltable.freeze;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
-import org.eclipse.statet.ecommons.waltable.viewport.IViewportDim;
-import org.eclipse.statet.ecommons.waltable.viewport.ViewportLayer;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.viewport.core.ViewportLayer;
 
 
 public class FreezeSelectionStrategy implements IFreezeCoordinatesProvider {
@@ -50,9 +49,9 @@ public class FreezeSelectionStrategy implements IFreezeCoordinatesProvider {
 	}
 	
 	private long checkPosition(final Orientation orientation, final long maxPosition) {
-		final IViewportDim dim= this.viewportLayer.getDim(orientation);
-		if (dim.getSize() > 0) {
-			final long position= dim.getOriginPosition();
+		final var viewportDim= this.viewportLayer.getDim(orientation);
+		if (viewportDim.getSize() > 0) {
+			final long position= viewportDim.getOriginPosition();
 			if (position < maxPosition) {
 				return position;
 			}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/IFreezeCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/IFreezeCommand.java
index 03888b4e..d080322e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/IFreezeCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/IFreezeCommand.java
@@ -13,15 +13,15 @@
 
 package org.eclipse.statet.ecommons.waltable.freeze;
 
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
 
 
 /**
  * Interface to mark commands as freeze related commands that are handled by
- * the {@link FreezeCommandHandler} or any command handler that handles {@link ILayerCommand}s
+ * the {@link FreezeCommandHandler} or any command handler that handles {@link LayerCommand}s
  * of this type.
  */
-public interface IFreezeCommand extends ILayerCommand {
+public interface IFreezeCommand extends LayerCommand {
 
 	/**
 	 * Indicates whether this command should toggle the frozen state between
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/IFreezeConfigAttributes.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/IFreezeConfigAttributes.java
index debdc2c1..f8cf34da 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/IFreezeConfigAttributes.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/IFreezeConfigAttributes.java
@@ -15,7 +15,7 @@ package org.eclipse.statet.ecommons.waltable.freeze;
 
 import org.eclipse.swt.graphics.Color;
 
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
 
 
 public interface IFreezeConfigAttributes {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/IFreezeCoordinatesProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/IFreezeCoordinatesProvider.java
index 86d57f67..86d57f67 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/IFreezeCoordinatesProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/IFreezeCoordinatesProvider.java
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/UnFreezeGridCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/UnFreezeGridCommand.java
index ec871ce2..5f832399 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/UnFreezeGridCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/UnFreezeGridCommand.java
@@ -13,7 +13,7 @@
 
 package org.eclipse.statet.ecommons.waltable.freeze;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/core/CompositeFreezeLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/core/CompositeFreezeLayer.java
new file mode 100644
index 00000000..c861ee6f
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/core/CompositeFreezeLayer.java
@@ -0,0 +1,169 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.freeze.core;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import java.util.Map;
+import java.util.StringTokenizer;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.AbstractLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.CompositeLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
+import org.eclipse.statet.ecommons.waltable.freeze.FreezeCommandHandler;
+import org.eclipse.statet.ecommons.waltable.freeze.FreezeHelper;
+import org.eclipse.statet.ecommons.waltable.freeze.FreezeLayer;
+import org.eclipse.statet.ecommons.waltable.freeze.swt.CompositeFreezeLayerPainter;
+import org.eclipse.statet.ecommons.waltable.freeze.ui.action.DefaultFreezeGridBindings;
+import org.eclipse.statet.ecommons.waltable.grid.core.ClientAreaResizeCommand;
+import org.eclipse.statet.ecommons.waltable.grid.core.layers.DimensionallyDependentLayer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.viewport.core.ViewportLayer;
+import org.eclipse.statet.ecommons.waltable.viewport.core.ViewportSelectDimPositionsCommandHandler;
+
+
+@NonNullByDefault
+public class CompositeFreezeLayer extends CompositeLayer {
+	
+	
+	protected final FreezeLayer freezeLayer;
+	
+	protected final ViewportLayer viewportLayer;
+	
+	protected final SelectionLayer selectionLayer;
+	
+	
+	public CompositeFreezeLayer(final FreezeLayer freezeLayer, final ViewportLayer viewportLayer,
+			final SelectionLayer selectionLayer) {
+		this(freezeLayer, viewportLayer, selectionLayer, true);
+	}
+	
+	public CompositeFreezeLayer(final FreezeLayer freezeLayer, final ViewportLayer viewportLayer,
+			final SelectionLayer selectionLayer,
+			final boolean useDefaultConfiguration) {
+		super(2, 2);
+		this.freezeLayer= freezeLayer;
+		this.viewportLayer= viewportLayer;
+		this.selectionLayer= selectionLayer;
+		
+		setChildLayer("FROZEN_REGION", freezeLayer, 0, 0); //$NON-NLS-1$
+		setChildLayer("FROZEN_ROW_REGION", new DimensionallyDependentLayer( //$NON-NLS-1$
+						viewportLayer.getScrollableLayer(), viewportLayer, freezeLayer),
+				1, 0);
+		setChildLayer("FROZEN_COLUMN_REGION", new DimensionallyDependentLayer( //$NON-NLS-1$
+						viewportLayer.getScrollableLayer(), freezeLayer, viewportLayer),
+				0, 1);
+		setChildLayer("NONFROZEN_REGION", viewportLayer, 1, 1); //$NON-NLS-1$
+		
+		registerCommandHandlers();
+		
+		if (useDefaultConfiguration) {
+			addConfiguration(new DefaultFreezeGridBindings());
+		}
+	}
+	
+	
+	@Override
+	protected LayerPainter createPainter() {
+		return new CompositeFreezeLayerPainter(this);
+	}
+	
+	
+	public boolean isFrozen() {
+		return this.freezeLayer.isFrozen();
+	}
+	
+	@Override
+	protected void registerCommandHandlers() {
+		registerCommandHandler(new FreezeCommandHandler(this.freezeLayer, this.viewportLayer, this.selectionLayer));
+		
+		final AbstractLayer frozenRowLayer= (AbstractLayer) getChildLayerByLayoutCoordinate(1, 0);
+		frozenRowLayer.registerCommandHandler(new ViewportSelectDimPositionsCommandHandler(
+				frozenRowLayer, VERTICAL ));
+		
+		final AbstractLayer frozenColumnLayer= (AbstractLayer) getChildLayerByLayoutCoordinate(0, 1);
+		frozenColumnLayer.registerCommandHandler(new ViewportSelectDimPositionsCommandHandler(
+				frozenRowLayer, HORIZONTAL ));
+	}
+	
+	
+	@Override
+	public boolean doCommand(final LayerCommand command) {
+		//if this layer should handle a ClientAreaResizeCommand we have to ensure that
+		//it is only called on the ViewportLayer, as otherwise an undefined behaviour
+		//could occur because the ViewportLayer isn't informed about potential refreshes
+		if (command instanceof ClientAreaResizeCommand) {
+			this.viewportLayer.doCommand(command);
+		}
+		return super.doCommand(command);
+	}
+	
+	
+	// Persistence
+	
+	@Override
+	public void saveState(final String prefix, final Map<String, String> properties) {
+		PositionCoordinate coord= this.freezeLayer.getTopLeftPosition();
+		properties.put(prefix + FreezeLayer.PERSISTENCE_TOP_LEFT_POSITION, 
+				coord.columnPosition + Persistable.VALUE_SEPARATOR + coord.rowPosition);
+		
+		coord= this.freezeLayer.getBottomRightPosition();
+		properties.put(prefix + FreezeLayer.PERSISTENCE_BOTTOM_RIGHT_POSITION, 
+				coord.columnPosition + Persistable.VALUE_SEPARATOR + coord.rowPosition);
+		
+		super.saveState(prefix, properties);
+	}
+	
+	@Override
+	public void loadState(final String prefix, final Map<String, String> properties) {
+		String property= properties.get(prefix + FreezeLayer.PERSISTENCE_TOP_LEFT_POSITION);
+		PositionCoordinate topLeftPosition= null;
+		if (property != null) {
+			final StringTokenizer tok= new StringTokenizer(property, Persistable.VALUE_SEPARATOR);
+			final String columnPosition= tok.nextToken();
+			final String rowPosition= tok.nextToken();
+			topLeftPosition= new PositionCoordinate(this.freezeLayer, 
+					Long.parseLong(columnPosition), Long.parseLong(rowPosition));
+		}
+		
+		property= properties.get(prefix + FreezeLayer.PERSISTENCE_BOTTOM_RIGHT_POSITION);
+		PositionCoordinate bottomRightPosition= null;
+		if (property != null) {
+			final StringTokenizer tok= new StringTokenizer(property, Persistable.VALUE_SEPARATOR);
+			final String columnPosition= tok.nextToken();
+			final String rowPosition= tok.nextToken();
+			bottomRightPosition= new PositionCoordinate(this.freezeLayer, 
+					Long.parseLong(columnPosition), Long.parseLong(rowPosition));
+		}
+		
+		//only restore a freeze state if there is one persisted
+		if (topLeftPosition != null && bottomRightPosition != null) {
+			if (topLeftPosition.columnPosition == -1 && topLeftPosition.rowPosition == -1
+					&& bottomRightPosition.columnPosition == -1 && bottomRightPosition.rowPosition == -1) {
+				FreezeHelper.unfreeze(this.freezeLayer, this.viewportLayer);
+			} else {
+				FreezeHelper.freeze(this.freezeLayer, this.viewportLayer, topLeftPosition, bottomRightPosition);
+			}
+		}
+		
+		super.loadState(prefix, properties);
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/core/FreezeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/core/FreezeEvent.java
new file mode 100644
index 00000000..ee8c3b03
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/core/FreezeEvent.java
@@ -0,0 +1,41 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.freeze.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.GeneralStructuralChangeEvent;
+
+
+@NonNullByDefault
+public class FreezeEvent extends GeneralStructuralChangeEvent {
+	
+	
+	public FreezeEvent(final Layer layer) {
+		super(layer);
+	}
+	
+	@Override
+	public @Nullable FreezeEvent toLayer(final Layer targetLayer) {
+		if (targetLayer == getLayer()) {
+			return this;
+		}
+		
+		return new FreezeEvent(targetLayer);
+	}
+	
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/core/UnfreezeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/core/UnfreezeEvent.java
new file mode 100644
index 00000000..3ba152f2
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/core/UnfreezeEvent.java
@@ -0,0 +1,41 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.freeze.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.GeneralStructuralChangeEvent;
+
+
+@NonNullByDefault
+public class UnfreezeEvent extends GeneralStructuralChangeEvent {
+	
+	
+	public UnfreezeEvent(final Layer layer) {
+		super(layer);
+	}
+	
+	@Override
+	public @Nullable UnfreezeEvent toLayer(final Layer targetLayer) {
+		if (targetLayer == getLayer()) {
+			return this;
+		}
+		
+		return new UnfreezeEvent(targetLayer);
+	}
+	
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/swt/CompositeFreezeLayerPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/swt/CompositeFreezeLayerPainter.java
new file mode 100644
index 00000000..c2e3208a
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/swt/CompositeFreezeLayerPainter.java
@@ -0,0 +1,74 @@
+/*=============================================================================#
+ # Copyright (c) 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.freeze.swt;
+
+import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
+
+import org.eclipse.swt.graphics.Color;
+import org.eclipse.swt.graphics.GC;
+import org.eclipse.swt.graphics.Rectangle;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.CompositeLayer.CompositeLayerPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.freeze.IFreezeConfigAttributes;
+import org.eclipse.statet.ecommons.waltable.freeze.core.CompositeFreezeLayer;
+import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
+
+
+@NonNullByDefault
+public class CompositeFreezeLayerPainter extends CompositeLayerPainter {
+	
+	
+	public CompositeFreezeLayerPainter(final CompositeFreezeLayer layer) {
+		super(layer);
+	}
+	
+	
+	protected Layer getFreezeLayer() {
+		return this.layer.getChildLayerByLayoutCoordinate(0, 0);
+	}
+	
+	@Override
+	public void paintLayer(final Layer natLayer, final GC gc, final int xOffset, final int yOffset,
+			final Rectangle rectangle, final ConfigRegistry configRegistry) {
+		super.paintLayer(natLayer, gc, xOffset, yOffset, rectangle, configRegistry);
+		final var freezeLayer= getFreezeLayer();
+		
+		Color separatorColor= configRegistry.getAttribute(IFreezeConfigAttributes.SEPARATOR_COLOR, DisplayMode.NORMAL);
+		if (separatorColor == null) {
+			separatorColor= GUIHelper.COLOR_BLUE;
+		}
+		
+		gc.setClipping(rectangle);
+		final Color oldFg= gc.getForeground();
+		gc.setForeground(separatorColor);
+		final long freezeWidth= freezeLayer.getWidth() - 1;
+		if (freezeWidth > 0) {
+			gc.drawLine(safe(xOffset + freezeWidth), yOffset,
+					safe(xOffset + freezeWidth), safe(yOffset + this.layer.getHeight() - 1));
+		}
+		final long freezeHeight= freezeLayer.getHeight() - 1;
+		if (freezeHeight > 0) {
+			gc.drawLine(xOffset, safe(yOffset + freezeHeight),
+					safe(xOffset + this.layer.getWidth() - 1), safe(yOffset + freezeHeight));
+		}
+		gc.setForeground(oldFg);
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/config/DefaultFreezeGridBindings.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/ui/action/DefaultFreezeGridBindings.java
index e92a1785..e54df16c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/config/DefaultFreezeGridBindings.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/ui/action/DefaultFreezeGridBindings.java
@@ -11,24 +11,31 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.freeze.config;
+package org.eclipse.statet.ecommons.waltable.freeze.ui.action;
 
 import org.eclipse.swt.SWT;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
 import org.eclipse.statet.ecommons.waltable.config.AbstractUiBindingConfiguration;
-import org.eclipse.statet.ecommons.waltable.freeze.action.FreezeGridAction;
-import org.eclipse.statet.ecommons.waltable.freeze.action.UnFreezeGridAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.KeyEventMatcher;
 
 
+@NonNullByDefault
 public class DefaultFreezeGridBindings extends AbstractUiBindingConfiguration {
 	
 	
+	public DefaultFreezeGridBindings() {
+	}
+	
+	
 	@Override
 	public void configureUiBindings(final UiBindingRegistry uiBindingRegistry) {
-		uiBindingRegistry.registerKeyBinding(new KeyEventMatcher(SWT.MOD1 | SWT.MOD2, 'f'), new FreezeGridAction());
-		uiBindingRegistry.registerKeyBinding(new KeyEventMatcher(SWT.MOD1 | SWT.MOD2, 'u'), new UnFreezeGridAction());
+		uiBindingRegistry.registerKeyBinding(new KeyEventMatcher(SWT.MOD1 | SWT.MOD2, 'f'),
+				new FreezeGridAction() );
+		uiBindingRegistry.registerKeyBinding(new KeyEventMatcher(SWT.MOD1 | SWT.MOD2, 'u'),
+				new UnFreezeGridAction() );
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/action/FreezeGridAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/ui/action/FreezeGridAction.java
index 829b64cd..fdaccc3d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/action/FreezeGridAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/ui/action/FreezeGridAction.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.freeze.action;
+package org.eclipse.statet.ecommons.waltable.freeze.ui.action;
 
 import org.eclipse.swt.events.KeyEvent;
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/action/UnFreezeGridAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/ui/action/UnFreezeGridAction.java
index 92abca65..670f22ae 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/freeze/action/UnFreezeGridAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/freeze/ui/action/UnFreezeGridAction.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.freeze.action;
+package org.eclipse.statet.ecommons.waltable.freeze.ui.action;
 
 import org.eclipse.swt.events.KeyEvent;
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/LayerPrinter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/LayerPrinter.java
index f08f9e7f..2253e55a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/LayerPrinter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/LayerPrinter.java
@@ -19,6 +19,7 @@ import java.util.Date;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Point;
+import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.graphics.Transform;
 import org.eclipse.swt.printing.PrintDialog;
 import org.eclipse.swt.printing.Printer;
@@ -27,11 +28,11 @@ import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Shell;
 
 import org.eclipse.statet.ecommons.waltable.Messages;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
-import org.eclipse.statet.ecommons.waltable.ui.IClientAreaProvider;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.ClientAreaProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
 
 
 /**
@@ -41,9 +42,9 @@ import org.eclipse.statet.ecommons.waltable.ui.IClientAreaProvider;
  */
 public class LayerPrinter {
 
-	private final IConfigRegistry configRegistry;
-	private final ILayer layer;
-	private final IClientAreaProvider originalClientAreaProvider;
+	private final ConfigRegistry configRegistry;
+	private final Layer layer;
+	private final ClientAreaProvider originalClientAreaProvider;
 	public static final int FOOTER_HEIGHT_IN_PRINTER_DPI= 300;
 
 	final SimpleDateFormat dateFormat= new SimpleDateFormat("EEE, d MMM yyyy HH:mm a"); //$NON-NLS-1$
@@ -56,7 +57,7 @@ public class LayerPrinter {
 	 * 			the CompositeLayer, otherwise the ViewportLayer is a good choice.
 	 * @param configRegistry The ConfigRegistry needed for rendering to the print GC.
 	 */
-	public LayerPrinter(final ILayer layer, final IConfigRegistry configRegistry) {
+	public LayerPrinter(final Layer layer, final ConfigRegistry configRegistry) {
 		this.layer= layer;
 		this.configRegistry= configRegistry;
 		this.originalClientAreaProvider= layer.getClientAreaProvider();
@@ -176,10 +177,10 @@ public class LayerPrinter {
 	 */
 	private LRectangle computePrintArea(final Printer printer) {
 		// Get the printable area
-		final org.eclipse.swt.graphics.Rectangle rect= printer.getClientArea();
+		final Rectangle rect= printer.getClientArea();
 
 		// Compute the trim
-		final org.eclipse.swt.graphics.Rectangle trim= printer.computeTrim(0, 0, 0, 0);
+		final Rectangle trim= printer.computeTrim(0, 0, 0, 0);
 
 		// Get the printer's DPI
 		final Point dpi= printer.getDPI();
@@ -251,7 +252,7 @@ public class LayerPrinter {
 					for (int horizontalPageNumber= 0; horizontalPageNumber < pageCount.x; horizontalPageNumber++) {
 
 						// Calculate bounds for the next page
-						final org.eclipse.swt.graphics.Rectangle printBounds= SWTUtil.toSWT(new LRectangle(
+						final Rectangle printBounds= SwtUtils.toSWT(new LRectangle(
 								(printerClientArea.width / scaleFactor.x) * horizontalPageNumber,
 								((printerClientArea.height - FOOTER_HEIGHT_IN_PRINTER_DPI) / scaleFactor.y) * verticalPageNumber,
 								printerClientArea.width / scaleFactor.x,
@@ -306,7 +307,7 @@ public class LayerPrinter {
 			else {
 				final LRectangle fullLayerSize= getTotalArea();
 				
-				LayerPrinter.this.layer.setClientAreaProvider(new IClientAreaProvider(){
+				LayerPrinter.this.layer.setClientAreaProvider(new ClientAreaProvider(){
 					@Override
 					public LRectangle getClientArea() {
 						return fullLayerSize;
@@ -324,8 +325,9 @@ public class LayerPrinter {
 		 * @param gc The print GC to render the layer to.
 		 * @param printBounds The bounds of the print page.
 		 */
-		private void printLayer(final GC gc, final org.eclipse.swt.graphics.Rectangle printBounds) {
-			LayerPrinter.this.layer.getLayerPainter().paintLayer(LayerPrinter.this.layer, gc, 0, 0, printBounds, LayerPrinter.this.configRegistry);
+		private void printLayer(final GC gc, final Rectangle printBounds) {
+			final var layerPainter= LayerPrinter.this.layer.getLayerPainter();
+			layerPainter.paintLayer(LayerPrinter.this.layer, gc, 0, 0, printBounds, LayerPrinter.this.configRegistry);
 		}
 
 		/**
@@ -334,7 +336,7 @@ public class LayerPrinter {
 		 * @param totalPageCount The total number of pages that are printed.
 		 * @param printBounds The bounds of the print page.
 		 */
-		private void printFooter(final GC gc, final int totalPageCount, final org.eclipse.swt.graphics.Rectangle printBounds) {
+		private void printFooter(final GC gc, final int totalPageCount, final Rectangle printBounds) {
 			gc.setForeground(Display.getCurrent().getSystemColor(SWT.COLOR_BLACK));
 			gc.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_WHITE));
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/PrintCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/PrintCommand.java
index 8073158c..4bfb2df1 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/PrintCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/PrintCommand.java
@@ -15,21 +15,21 @@ package org.eclipse.statet.ecommons.waltable.print;
 
 import org.eclipse.swt.widgets.Shell;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
 
 
 public class PrintCommand extends AbstractContextFreeCommand {
 
-	private final IConfigRegistry configRegistry;
+	private final ConfigRegistry configRegistry;
 	private final Shell shell;
 
-	public PrintCommand(final IConfigRegistry configRegistry, final Shell shell) {
+	public PrintCommand(final ConfigRegistry configRegistry, final Shell shell) {
 		this.configRegistry= configRegistry;
 		this.shell= shell;
 	}
 	
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getConfigRegistry() {
 		return this.configRegistry;
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/PrintCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/PrintCommandHandler.java
index 18c78afd..6c17c27a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/PrintCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/PrintCommandHandler.java
@@ -13,35 +13,42 @@
 
 package org.eclipse.statet.ecommons.waltable.print;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 /**
  * ILayerCommandHandler for handling the PrintCommand.
  * Simply delegates to the 
  */
-public class PrintCommandHandler extends AbstractLayerCommandHandler<PrintCommand> {
-
-	private final ILayer layer;
-
+@NonNullByDefault
+public class PrintCommandHandler implements LayerCommandHandler<PrintCommand> {
+	
+	
+	private final Layer layer;
+	
+	
 	/**
 	 * @param layer The layer that should be printed. 
 	 * 			Usually the top most layer to print, e.g. the GridLayer.
 	 */
-	public PrintCommandHandler(final ILayer layer) {
+	public PrintCommandHandler(final Layer layer) {
 		this.layer= layer;
 	}
-
-	@Override
-	public boolean doCommand(final PrintCommand command) {
-		new LayerPrinter(this.layer, command.getConfigRegistry()).print(command.getShell());
-		return true;
-	}
-
+	
+	
 	@Override
 	public Class<PrintCommand> getCommandClass() {
 		return PrintCommand.class;
 	}
-
+	
+	@Override
+	public boolean executeCommand(final PrintCommand command) {
+		new LayerPrinter(this.layer, command.getConfigRegistry())
+				.print(command.getShell());
+		return true;
+	}
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/PrintEntireGridCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/PrintEntireGridCommand.java
index 3be82350..8ffe399b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/PrintEntireGridCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/PrintEntireGridCommand.java
@@ -13,7 +13,7 @@
 
 package org.eclipse.statet.ecommons.waltable.print;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/TurnViewportOffCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/TurnViewportOffCommand.java
index 1f6358f7..413ff349 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/TurnViewportOffCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/TurnViewportOffCommand.java
@@ -13,7 +13,7 @@
 
 package org.eclipse.statet.ecommons.waltable.print;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/TurnViewportOnCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/TurnViewportOnCommand.java
index 1453a686..fd7d51cd 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/TurnViewportOnCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/TurnViewportOnCommand.java
@@ -13,7 +13,7 @@
 
 package org.eclipse.statet.ecommons.waltable.print;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/config/DefaultPrintBindings.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/config/DefaultPrintBindings.java
index c302f787..15623ea2 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/config/DefaultPrintBindings.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/config/DefaultPrintBindings.java
@@ -16,7 +16,7 @@ package org.eclipse.statet.ecommons.waltable.print.config;
 import org.eclipse.swt.SWT;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractUiBindingConfiguration;
-import org.eclipse.statet.ecommons.waltable.print.action.PrintAction;
+import org.eclipse.statet.ecommons.waltable.print.ui.action.PrintAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.KeyEventMatcher;
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/action/PrintAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/ui/action/PrintAction.java
index d14e8a83..3de0ab6a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/print/action/PrintAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/print/ui/action/PrintAction.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.print.action;
+package org.eclipse.statet.ecommons.waltable.print.ui.action;
 
 import org.eclipse.swt.events.KeyEvent;
 
@@ -27,7 +27,7 @@ public class PrintAction implements IKeyAction {
 
 	@Override
 	public void run(final NatTable natTable, final KeyEvent event) {
-		natTable.doCommand(new PrintCommand(natTable.getConfigRegistry(), natTable.getShell()));
+		natTable.doCommand(new PrintCommand(natTable.getStyleRegistry(), natTable.getShell()));
 	}
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/ITickUpdateHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/ITickUpdateHandler.java
index c25e9d12..c25e9d12 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/ITickUpdateHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/ITickUpdateHandler.java
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateCommand.java
index c9f7ec37..bd7ee867 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateCommand.java
@@ -13,9 +13,9 @@
 
 package org.eclipse.statet.ecommons.waltable.tickupdate;
 
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 /**
@@ -24,17 +24,17 @@ import org.eclipse.statet.ecommons.waltable.layer.ILayer;
  * 		 SelectionLayer and the corresponding {@link TickUpdateCommandHandler}
  * 		 is registered.
  */
-public class TickUpdateCommand implements ILayerCommand {
+public class TickUpdateCommand implements LayerCommand {
 
 	/**
-	 * The {@link IConfigRegistry} of the current NatTable instance this
+	 * The {@link ConfigRegistry} of the current NatTable instance this
 	 * command is executed in. Needed to determine several configurations
 	 * on handling this command by its handler.
 	 * As the command handler is not aware of the NatTable instance it
-	 * is running in, and there is no kind of context, the {@link IConfigRegistry}
+	 * is running in, and there is no kind of context, the {@link ConfigRegistry}
 	 * needs to be transported.
 	 */
-	private final IConfigRegistry configRegistry;
+	private final ConfigRegistry configRegistry;
 	/**
 	 * Flag to determine whether the current value in the data model
 	 * should be incremented or decremented. 
@@ -42,16 +42,16 @@ public class TickUpdateCommand implements ILayerCommand {
 	private final boolean increment;
 
 	/**
-	 * @param configRegistry The {@link IConfigRegistry} of the current NatTable instance this
+	 * @param configRegistry The {@link ConfigRegistry} of the current NatTable instance this
 	 * 			command is executed in. Needed to determine several configurations
 	 * 			on handling this command by its handler.
 	 * 			As the command handler is not aware of the NatTable instance it
-	 * 			is running in, and there is no kind of context, the {@link IConfigRegistry}
+	 * 			is running in, and there is no kind of context, the {@link ConfigRegistry}
 	 * 			needs to be transported.
 	 * @param increment Flag to determine whether the current value in the data model
 	 * 			should be incremented or decremented. 
 	 */
-	public TickUpdateCommand(final IConfigRegistry configRegistry, final boolean increment) {
+	public TickUpdateCommand(final ConfigRegistry configRegistry, final boolean increment) {
 		this.configRegistry= configRegistry;
 		this.increment= increment;
 	}
@@ -71,20 +71,20 @@ public class TickUpdateCommand implements ILayerCommand {
 	}
 
 	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
+	public boolean convertToTargetLayer(final Layer targetLayer) {
 		// No op.
 		return true;
 	}
 	
 	/**
-	 * @return The {@link IConfigRegistry} of the current NatTable instance this
+	 * @return The {@link ConfigRegistry} of the current NatTable instance this
 	 * 			command is executed in. Needed to determine several configurations
 	 * 			on handling this command by its handler.
 	 * 			As the command handler is not aware of the NatTable instance it
-	 * 			is running in, and there is no kind of context, the {@link IConfigRegistry}
+	 * 			is running in, and there is no kind of context, the {@link ConfigRegistry}
 	 * 			needs to be transported.
 	 */
-	public IConfigRegistry getConfigRegistry() {
+	public ConfigRegistry getConfigRegistry() {
 		return this.configRegistry;
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateCommandHandler.java
index 90fc070f..f75d76cc 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateCommandHandler.java
@@ -18,17 +18,17 @@ import java.util.List;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.config.IEditableRule;
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 import org.eclipse.statet.ecommons.waltable.data.validate.IDataValidator;
 import org.eclipse.statet.ecommons.waltable.edit.EditConfigAttributes;
 import org.eclipse.statet.ecommons.waltable.edit.EditUtils;
 import org.eclipse.statet.ecommons.waltable.edit.UpdateDataCommand;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
@@ -55,7 +55,7 @@ public class TickUpdateCommandHandler extends AbstractLayerCommandHandler<TickUp
 	@Override
 	public boolean doCommand(final TickUpdateCommand command) {
 		final List<PositionCoordinate> selectedPositions= this.selectionLayer.getSelectedCellPositions();
-		final IConfigRegistry configRegistry= command.getConfigRegistry();
+		final ConfigRegistry configRegistry= command.getConfigRegistry();
 		
 		// Tick update for multiple cells in selection 
 		if (selectedPositions.size() > 1) {
@@ -84,20 +84,20 @@ public class TickUpdateCommandHandler extends AbstractLayerCommandHandler<TickUp
  	 * 			should be executed
 	 */
 	private void updateSingleCell(final TickUpdateCommand command, final PositionCoordinate selectedPosition) {
-		final ILayerCell cell= this.selectionLayer.getCellByPosition(
+		final LayerCell cell= this.selectionLayer.getCellByPosition(
 				selectedPosition.columnPosition, selectedPosition.rowPosition);
 		
-		final IConfigRegistry configRegistry= command.getConfigRegistry();
+		final ConfigRegistry configRegistry= command.getConfigRegistry();
 		
-		final IEditableRule editableRule= configRegistry.getConfigAttribute(
+		final IEditableRule editableRule= configRegistry.getAttribute(
 				EditConfigAttributes.CELL_EDITABLE_RULE, 
 				DisplayMode.EDIT,
-				cell.getConfigLabels().getLabels());
+				cell.getLabels().getLabels());
 		
-		final IDataValidator validator= configRegistry.getConfigAttribute(
+		final IDataValidator validator= configRegistry.getAttribute(
 				EditConfigAttributes.DATA_VALIDATOR, 
 				DisplayMode.EDIT, 
-				cell.getConfigLabels().getLabels());
+				cell.getLabels().getLabels());
 		
 		if (editableRule.isEditable(cell, configRegistry)) {
 			//process the tick update
@@ -131,11 +131,11 @@ public class TickUpdateCommandHandler extends AbstractLayerCommandHandler<TickUp
 	 * @param cell The cell on which the command should be processed
 	 * @return The processed value after the command was executed on the current cell value
 	 */
-	private Object getNewCellValue(final TickUpdateCommand command, final ILayerCell cell) {
-		final ITickUpdateHandler tickUpdateHandler= command.getConfigRegistry().getConfigAttribute(
+	private Object getNewCellValue(final TickUpdateCommand command, final LayerCell cell) {
+		final ITickUpdateHandler tickUpdateHandler= command.getConfigRegistry().getAttribute(
 				TickUpdateConfigAttributes.UPDATE_HANDLER,
 				DisplayMode.EDIT, 
-				cell.getConfigLabels().getLabels());
+				cell.getLabels().getLabels());
 
 		final Object dataValue= cell.getDataValue(0, null);
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateConfigAttributes.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateConfigAttributes.java
index b85d35cb..e894e34d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateConfigAttributes.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/TickUpdateConfigAttributes.java
@@ -13,8 +13,8 @@
 
 package org.eclipse.statet.ecommons.waltable.tickupdate;
 
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigAttribute;
 import org.eclipse.statet.ecommons.waltable.edit.gui.TickUpdateCellEditDialog;
-import org.eclipse.statet.ecommons.waltable.style.ConfigAttribute;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/config/DefaultTickUpdateConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/config/DefaultTickUpdateConfiguration.java
index e5547ee6..04083dbd 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/config/DefaultTickUpdateConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/config/DefaultTickUpdateConfiguration.java
@@ -16,12 +16,12 @@ package org.eclipse.statet.ecommons.waltable.tickupdate.config;
 import org.eclipse.swt.SWT;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractLayerConfiguration;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 import org.eclipse.statet.ecommons.waltable.tickupdate.ITickUpdateHandler;
 import org.eclipse.statet.ecommons.waltable.tickupdate.TickUpdateCommandHandler;
 import org.eclipse.statet.ecommons.waltable.tickupdate.TickUpdateConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.tickupdate.action.TickUpdateAction;
+import org.eclipse.statet.ecommons.waltable.tickupdate.ui.action.TickUpdateAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.KeyEventMatcher;
 
@@ -35,8 +35,8 @@ import org.eclipse.statet.ecommons.waltable.ui.matcher.KeyEventMatcher;
 public class DefaultTickUpdateConfiguration extends AbstractLayerConfiguration<SelectionLayer> {
 	
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
-		configRegistry.registerConfigAttribute(
+	public void configureRegistry(final ConfigRegistry configRegistry) {
+		configRegistry.registerAttribute(
 				TickUpdateConfigAttributes.UPDATE_HANDLER, ITickUpdateHandler.DEFAULT_TICK_UPDATE_HANDLER);
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/action/TickUpdateAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/ui/action/TickUpdateAction.java
index c225753d..87d4f6f8 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/tickupdate/action/TickUpdateAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcAdditional/org/eclipse/statet/ecommons/waltable/tickupdate/ui/action/TickUpdateAction.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.tickupdate.action;
+package org.eclipse.statet.ecommons.waltable.tickupdate.ui.action;
 
 import org.eclipse.swt.events.KeyEvent;
 
@@ -43,7 +43,7 @@ public class TickUpdateAction implements IKeyAction {
 
 	@Override
 	public void run(final NatTable natTable, final KeyEvent event) {
-		natTable.doCommand(new TickUpdateCommand(natTable.getConfigRegistry(), this.increment));
+		natTable.doCommand(new TickUpdateCommand(natTable.getStyleRegistry(), this.increment));
 	}
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/DataLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/DataLayer.java
index 19471346..c5917c92 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/DataLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/DataLayer.java
@@ -11,51 +11,60 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.data.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import java.util.Properties;
+import java.util.Map;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.command.StructuralRefreshCommandHandler;
-import org.eclipse.statet.ecommons.waltable.command.VisualRefreshCommandHandler;
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.AbstractLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.BasicLayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.BasicLayerCellDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.GeneralStructuralChangeEvent;
 import org.eclipse.statet.ecommons.waltable.edit.UpdateDataCommandHandler;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCellDim;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCellDim;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralRefreshEvent;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
-import org.eclipse.statet.ecommons.waltable.resize.ColumnResizeEvent;
-import org.eclipse.statet.ecommons.waltable.resize.MultiColumnResizeCommandHandler;
-import org.eclipse.statet.ecommons.waltable.resize.MultiRowResizeCommandHandler;
-import org.eclipse.statet.ecommons.waltable.resize.PositionResizeCommandHandler;
-import org.eclipse.statet.ecommons.waltable.resize.RowResizeEvent;
+import org.eclipse.statet.ecommons.waltable.refresh.core.StructuralRefreshCommandHandler;
+import org.eclipse.statet.ecommons.waltable.refresh.core.VisualRefreshCommandHandler;
+import org.eclipse.statet.ecommons.waltable.resize.core.DimResizeEvent;
+import org.eclipse.statet.ecommons.waltable.resize.core.MultiColumnResizeCommandHandler;
+import org.eclipse.statet.ecommons.waltable.resize.core.MultiRowResizeCommandHandler;
+import org.eclipse.statet.ecommons.waltable.resize.core.PositionResizeCommandHandler;
 
 
 /**
- * Wraps the {@link IDataProvider}, and serves as the data source for all
+ * Wraps the {@link DataProvider}, and serves as the data source for all
  * other layers. Also, tracks the size of the columns and the rows using
  * {@link SizeConfig} objects. Since this layer sits directly on top of the
  * data source, at this layer index == position.
  */
-public class DataLayer extends AbstractLayer implements ILayer {
+@NonNullByDefault
+public class DataLayer extends AbstractLayer<DataLayerDim<? extends DataLayer>> implements Layer {
 	
 	
-	protected class DataLayerCell extends LayerCell {
+	protected class DataLayerCell extends BasicLayerCell {
 		
 		
-		public DataLayerCell(final ILayerCellDim horizontalDim, final ILayerCellDim verticalDim) {
+		public DataLayerCell(final LayerCellDim horizontalDim, final LayerCellDim verticalDim) {
 			super(DataLayer.this, horizontalDim, verticalDim);
 		}
 		
 		
 		@Override
-		public Object getDataValue(final int flags, final IProgressMonitor monitor) {
+		public @Nullable Object getDataValue(final int flags,
+				final @Nullable IProgressMonitor monitor) {
 			return DataLayer.this.dataProvider.getDataValue(getColumnPosition(), getRowPosition(),
 					flags, monitor );
 		}
@@ -70,7 +79,7 @@ public class DataLayer extends AbstractLayer implements ILayer {
 	public static final int DEFAULT_ROW_HEIGHT= 20;
 	
 	
-	protected IDataProvider dataProvider;
+	protected DataProvider dataProvider;
 	
 	private final long columnIdCat;
 	private final SizeConfig columnWidthConfig;
@@ -79,13 +88,13 @@ public class DataLayer extends AbstractLayer implements ILayer {
 	private final SizeConfig rowHeightConfig;
 	
 	
-	public DataLayer(final IDataProvider dataProvider, final long idCat) {
+	public DataLayer(final DataProvider dataProvider, final long idCat) {
 		this(dataProvider,
 				idCat, DEFAULT_COLUMN_WIDTH,
 				idCat, DEFAULT_ROW_HEIGHT );
 	}
 	
-	public DataLayer(final IDataProvider dataProvider,
+	public DataLayer(final DataProvider dataProvider,
 			final long columnIdCat, final int defaultColumnWidth,
 			final long rowIdCat, final int defaultRowHeight) {
 		this(dataProvider,
@@ -93,57 +102,59 @@ public class DataLayer extends AbstractLayer implements ILayer {
 				rowIdCat, new SizeConfig(defaultRowHeight) );
 	}
 	
-	public DataLayer(final IDataProvider dataProvider,
+	public DataLayer(final DataProvider dataProvider,
 			final long columnIdCat, final SizeConfig columnWidthConfig,
 			final long rowIdCat, final SizeConfig rowHeightConfig) {
 		this.columnIdCat= columnIdCat;
 		this.columnWidthConfig= columnWidthConfig;
 		this.rowIdCat= rowIdCat;
 		this.rowHeightConfig= rowHeightConfig;
-		initDims();
+		
+		init();
 		
 		registerCommandHandlers();
 		
 		setDataProvider(dataProvider);
 	}
 	
-	
 	@Override
-	protected void initDims() {
-		if (this.columnIdCat == 0 || this.rowIdCat == 0) {
-			return;
+	protected DataLayerDim<? extends DataLayer> createDim(final Orientation orientation) {
+		switch (orientation) {
+		case HORIZONTAL:
+			return new SizeConfigDim<>(this, HORIZONTAL, this.columnIdCat, this.columnWidthConfig) {
+				@Override
+				public long getPositionCount() {
+					return DataLayer.this.dataProvider.getColumnCount();
+				}
+			};
+		case VERTICAL:
+			return new SizeConfigDim<>(this, VERTICAL, this.rowIdCat, this.rowHeightConfig) {
+				@Override
+				public long getPositionCount() {
+					return DataLayer.this.dataProvider.getRowCount();
+				}
+			};
+		default:
+			throw new IllegalStateException();
 		}
-		
-		setDim(new SizeConfigDim<ILayer>(this, HORIZONTAL, this.columnIdCat, this.columnWidthConfig) {
-			@Override
-			public long getPositionCount() {
-				return DataLayer.this.dataProvider.getColumnCount();
-			}
-		});
-		setDim(new SizeConfigDim<ILayer>(this, VERTICAL, this.rowIdCat, this.rowHeightConfig) {
-			@Override
-			public long getPositionCount() {
-				return DataLayer.this.dataProvider.getRowCount();
-			}
-		});
 	}
 	
 	
 	// Persistence
 	
 	@Override
-	public void saveState(final String prefix, final Properties properties) {
+	public void saveState(final String prefix, final Map<String, String> properties) {
 		super.saveState(prefix, properties);
 		this.columnWidthConfig.saveState(prefix + PERSISTENCE_KEY_COLUMN_WIDTH, properties);
 		this.rowHeightConfig.saveState(prefix + PERSISTENCE_KEY_ROW_HEIGHT, properties);
 	}
 	
 	@Override
-	public void loadState(final String prefix, final Properties properties) {
+	public void loadState(final String prefix, final Map<String, String> properties) {
 		super.loadState(prefix, properties);
 		this.columnWidthConfig.loadState(prefix + PERSISTENCE_KEY_COLUMN_WIDTH, properties);
 		this.rowHeightConfig.loadState(prefix + PERSISTENCE_KEY_ROW_HEIGHT, properties);
-		fireLayerEvent(new StructuralRefreshEvent(this));
+		fireLayerEvent(new GeneralStructuralChangeEvent(this));
 	}
 	
 	// Configuration
@@ -154,23 +165,23 @@ public class DataLayer extends AbstractLayer implements ILayer {
 		registerCommandHandler(new MultiColumnResizeCommandHandler(this));
 		registerCommandHandler(new MultiRowResizeCommandHandler(this));
 		registerCommandHandler(new UpdateDataCommandHandler(this));
-		registerCommandHandler(new StructuralRefreshCommandHandler());
-		registerCommandHandler(new VisualRefreshCommandHandler());
+		registerCommandHandler(new StructuralRefreshCommandHandler(this));
+		registerCommandHandler(new VisualRefreshCommandHandler(this));
 	}
 	
-	public IDataProvider getDataProvider() {
+	public DataProvider getDataProvider() {
 		return this.dataProvider;
 	}
 	
-	protected void setDataProvider(final IDataProvider dataProvider) {
-		if (this.dataProvider instanceof IPersistable) {
-			unregisterPersistable((IPersistable) this.dataProvider);
+	protected void setDataProvider(final DataProvider dataProvider) {
+		if (this.dataProvider instanceof Persistable) {
+			unregisterPersistable((Persistable) this.dataProvider);
 		}
 		
 		this.dataProvider= dataProvider;
 		
-		if (dataProvider instanceof IPersistable) {
-			registerPersistable((IPersistable) dataProvider);
+		if (dataProvider instanceof Persistable) {
+			registerPersistable((Persistable) dataProvider);
 		}
 	}
 	
@@ -179,7 +190,7 @@ public class DataLayer extends AbstractLayer implements ILayer {
 	
 	public void setColumnWidthByPosition(final long columnPosition, final int width) {
 		this.columnWidthConfig.setSize(columnPosition, width);
-		fireLayerEvent(new ColumnResizeEvent(this, columnPosition));
+		fireLayerEvent(new DimResizeEvent(getDim(HORIZONTAL), new LRange(columnPosition)));
 	}
 	
 	public void setDefaultColumnWidth(final int width) {
@@ -206,7 +217,7 @@ public class DataLayer extends AbstractLayer implements ILayer {
 	
 	public void setRowHeightByPosition(final long rowPosition, final int height) {
 		this.rowHeightConfig.setSize(rowPosition, height);
-		fireLayerEvent(new RowResizeEvent(this, rowPosition));
+		fireLayerEvent(new DimResizeEvent(getDim(VERTICAL), new LRange(rowPosition)));
 	}
 	
 	public void setDefaultRowHeight(final int height) {
@@ -231,19 +242,19 @@ public class DataLayer extends AbstractLayer implements ILayer {
 	// Cell features
 	
 	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
-		final ILayerDim hDim= getDim(HORIZONTAL);
-		final ILayerDim vDim= getDim(VERTICAL);
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+		final LayerDim hDim= getDim(HORIZONTAL);
+		final LayerDim vDim= getDim(VERTICAL);
 		final long columnId= hDim.getPositionId(columnPosition, columnPosition);
 		final long rowId= vDim.getPositionId(rowPosition, rowPosition);
 		
 		return new DataLayerCell(
-				new LayerCellDim(HORIZONTAL, columnId, columnPosition),
-				new LayerCellDim(VERTICAL, rowId, rowPosition) );
+				new BasicLayerCellDim(HORIZONTAL, columnId, columnPosition),
+				new BasicLayerCellDim(VERTICAL, rowId, rowPosition) );
 	}
 	
 	@Override
-	public ILayer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
+	public @Nullable Layer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
 		return null;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/DataDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/DataLayerDim.java
index 1d26c6ac..9965d2e1 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/DataDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/DataLayerDim.java
@@ -11,25 +11,33 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.data.core;
 
 import java.util.Collection;
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.coordinate.PixelOutOfBoundsException;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionId;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PixelOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionId;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.layer.AbstractLayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
 
-public abstract class DataDim<TLayer extends ILayer> extends AbstractLayerDim<TLayer> {
+
+@NonNullByDefault
+public abstract class DataLayerDim<TLayer extends Layer> extends AbstractLayerDim<TLayer> {
 	
 	
 	private final long idCat;
 	
 	
-	public DataDim(final TLayer layer, final Orientation orientation,
+	public DataLayerDim(final TLayer layer, final Orientation orientation,
 			final long idCat) {
 		super(layer, orientation);
 		
@@ -40,7 +48,7 @@ public abstract class DataDim<TLayer extends ILayer> extends AbstractLayerDim<TL
 	@Override
 	public long getPositionId(final long refPosition, final long position) {
 		if (position < 0 || position >= getPositionCount()) {
-			throw PositionOutOfBoundsException.position(position, getOrientation());
+			throw new PositionOutOfBoundsException(position, getOrientation());
 		}
 		return (this.idCat | position);
 	}
@@ -63,18 +71,18 @@ public abstract class DataDim<TLayer extends ILayer> extends AbstractLayerDim<TL
 	}
 	
 	@Override
-	public long underlyingToLocalPosition(final ILayerDim sourceUnderlyingDim, final long underlyingPosition) {
-		return underlyingPosition;
+	public long underlyingToLocalPosition(final LayerDim sourceUnderlyingDim, final long underlyingPosition) {
+		throw new IllegalArgumentException("underlyingLayer"); //$NON-NLS-1$
 	}
 	
 	@Override
-	public List<LRange> underlyingToLocalPositions(final ILayerDim sourceUnderlyingDim,
+	public List<LRange> underlyingToLocalPositions(final LayerDim sourceUnderlyingDim,
 			final Collection<LRange> underlyingPositions) {
-		return null;
+		throw new IllegalArgumentException("underlyingLayer"); //$NON-NLS-1$
 	}
 	
 	@Override
-	public List<ILayerDim> getUnderlyingDimsByPosition(final long position) {
+	public @Nullable ImList<LayerDim> getUnderlyingDimsByPosition(final long position) {
 		return null;
 	}
 	
@@ -90,7 +98,7 @@ public abstract class DataDim<TLayer extends ILayer> extends AbstractLayerDim<TL
 		long endPixel= getSize();
 		
 		if (pixel < startPixel || pixel >= endPixel) {
-			throw PixelOutOfBoundsException.pixel(pixel, getOrientation());
+			throw new PixelOutOfBoundsException(pixel, getOrientation());
 		}
 		
 		long startPosition= 0;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/SizeConfig.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/SizeConfig.java
index c70c772c..20273928 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/SizeConfig.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/SizeConfig.java
@@ -11,15 +11,16 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.data.core;
 
 import java.util.Map;
-import java.util.Properties;
 import java.util.StringTokenizer;
 import java.util.TreeMap;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
 
 
 /**
@@ -29,7 +30,8 @@ import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
  * The mixed mode is only working if percentage sizing is enabled globally, and 
  * the fixed sized positions are marked separately.
  */
-public class SizeConfig implements IPersistable {
+@NonNullByDefault
+public class SizeConfig implements Persistable {
 	
 	
 	public static final String PERSISTENCE_KEY_DEFAULT_SIZE= ".defaultSize"; //$NON-NLS-1$
@@ -76,7 +78,7 @@ public class SizeConfig implements IPersistable {
 	// Persistence
 	
 	@Override
-	public void saveState(final String prefix, final Properties properties) {
+	public void saveState(final String prefix, final Map<String, String> properties) {
 		properties.put(prefix + PERSISTENCE_KEY_DEFAULT_SIZE, String.valueOf(this.defaultSize));
 		saveMap(this.defaultSizeMap, prefix + PERSISTENCE_KEY_DEFAULT_SIZES, properties);
 		saveMap(this.sizeMap, prefix + PERSISTENCE_KEY_SIZES, properties);
@@ -84,7 +86,7 @@ public class SizeConfig implements IPersistable {
 		saveMap(this.resizablesMap, prefix + PERSISTENCE_KEY_RESIZABLE_INDEXES, properties);
 	}
 	
-	private void saveMap(final Map<Long, ?> map, final String key, final Properties properties) {
+	private void saveMap(final Map<Long, ?> map, final String key, final Map<String, String> properties) {
 		if (map.size() > 0) {
 			final StringBuilder strBuilder= new StringBuilder();
 			for (final Long index : map.keySet()) {
@@ -93,25 +95,25 @@ public class SizeConfig implements IPersistable {
 				strBuilder.append(map.get(index));
 				strBuilder.append(',');
 			}
-			properties.setProperty(key, strBuilder.toString());
+			properties.put(key, strBuilder.toString());
 		}
 	}
 	
 	@Override
-	public void loadState(final String prefix, final Properties properties) {
+	public void loadState(final String prefix, final Map<String, String> properties) {
 		//ensure to cleanup the current states prior loading new ones
 		this.defaultSizeMap.clear();
 		this.sizeMap.clear();
 		this.resizablesMap.clear();
 		
-		final String persistedDefaultSize= properties.getProperty(prefix + PERSISTENCE_KEY_DEFAULT_SIZE);
+		final String persistedDefaultSize= properties.get(prefix + PERSISTENCE_KEY_DEFAULT_SIZE);
 		if (persistedDefaultSize != null && !persistedDefaultSize.isEmpty()) {
-			this.defaultSize= Integer.valueOf(persistedDefaultSize).intValue();
+			this.defaultSize= Integer.parseInt(persistedDefaultSize);
 		}
 		
-		final String persistedResizableDefault= properties.getProperty(prefix + PERSISTENCE_KEY_RESIZABLE_BY_DEFAULT);
+		final String persistedResizableDefault= properties.get(prefix + PERSISTENCE_KEY_RESIZABLE_BY_DEFAULT);
 		if (persistedResizableDefault != null && !persistedResizableDefault.isEmpty()) {
-			this.resizableByDefault= Boolean.valueOf(persistedResizableDefault).booleanValue();
+			this.resizableByDefault= Boolean.parseBoolean(persistedResizableDefault);
 		}
 		
 		loadBooleanMap(prefix + PERSISTENCE_KEY_RESIZABLE_INDEXES, properties, this.resizablesMap);
@@ -119,8 +121,8 @@ public class SizeConfig implements IPersistable {
 		loadIntegerMap(prefix + PERSISTENCE_KEY_SIZES, properties, this.sizeMap);
 	}
 	
-	private void loadIntegerMap(final String key, final Properties properties, final Map<Long, Integer> map) {
-		final String property= properties.getProperty(key);
+	private void loadIntegerMap(final String key, final Map<String, String> properties, final Map<Long, Integer> map) {
+		final String property= properties.get(key);
 		if (property != null) {
 			map.clear();
 			
@@ -133,8 +135,8 @@ public class SizeConfig implements IPersistable {
 		}
 	}
 	
-	private void loadBooleanMap(final String key, final Properties properties, final Map<Long, Boolean> map) {
-		final String property= properties.getProperty(key);
+	private void loadBooleanMap(final String key, final Map<String, String> properties, final Map<Long, Boolean> map) {
+		final String property= properties.get(key);
 		if (property != null) {
 			final StringTokenizer tok= new StringTokenizer(property, ","); //$NON-NLS-1$
 			while (tok.hasMoreTokens()) {
@@ -174,7 +176,7 @@ public class SizeConfig implements IPersistable {
 	
 	public long getAggregateSize(final long position) {
 		if (position < 0) {
-			throw PositionOutOfBoundsException.position(position);
+			throw new PositionOutOfBoundsException(position);
 		}
 		else if (position == 0) {
 			return 0;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/SizeConfigDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/SizeConfigDim.java
index ea72305e..db98952f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/SizeConfigDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/SizeConfigDim.java
@@ -11,18 +11,22 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.data.core;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
-public abstract class SizeConfigDim<TLayer extends ILayer> extends DataDim<ILayer> {
+
+@NonNullByDefault
+public abstract class SizeConfigDim<TLayer extends Layer> extends DataLayerDim<TLayer> {
 	
 	
 	private final SizeConfig sizeConfig;
 	
 	
-	public SizeConfigDim(final ILayer layer, final Orientation orientation,
+	public SizeConfigDim(final TLayer layer, final Orientation orientation,
 			final long idCat, final SizeConfig sizeConfig) {
 		super(layer, orientation, idCat);
 		
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/SpanningDataLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/SpanningDataLayer.java
index b621ce66..c0df8d23 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/layer/SpanningDataLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/data/core/SpanningDataLayer.java
@@ -11,21 +11,25 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.layer;
+package org.eclipse.statet.ecommons.waltable.data.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.data.ISpanningDataProvider;
-import org.eclipse.statet.ecommons.waltable.layer.cell.DataCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCellDim;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.data.DataCell;
+import org.eclipse.statet.ecommons.waltable.core.data.SpanningDataProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.BasicLayerCellDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
 
+
+@NonNullByDefault
 public class SpanningDataLayer extends DataLayer {
 	
 	
-	public SpanningDataLayer(final ISpanningDataProvider dataProvider,
+	public SpanningDataLayer(final SpanningDataProvider dataProvider,
 			final long columnIdCat, final int defaultColumnWidth,
 			final long rowIdCat, final int defaultRowHeight) {
 		super(dataProvider,
@@ -35,23 +39,23 @@ public class SpanningDataLayer extends DataLayer {
 	
 	
 	@Override
-	public ISpanningDataProvider getDataProvider() {
-		return (ISpanningDataProvider) super.getDataProvider();
+	public SpanningDataProvider getDataProvider() {
+		return (SpanningDataProvider)super.getDataProvider();
 	}
 	
 	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
-		final ILayerDim hDim= getDim(HORIZONTAL);
-		final ILayerDim vDim= getDim(VERTICAL);
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+		final LayerDim hDim= getDim(HORIZONTAL);
+		final LayerDim vDim= getDim(VERTICAL);
 		final long columnId= hDim.getPositionId(columnPosition, columnPosition);
 		final long rowId= vDim.getPositionId(rowPosition, rowPosition);
 		
 		final DataCell dataCell= getDataProvider().getCellByPosition(columnPosition, rowPosition);
 		
 		return new DataLayerCell(
-				new LayerCellDim(HORIZONTAL, columnId, columnPosition,
+				new BasicLayerCellDim(HORIZONTAL, columnId, columnPosition,
 						dataCell.getColumnPosition(), dataCell.getColumnSpan() ),
-				new LayerCellDim(VERTICAL, rowId, rowPosition,
+				new BasicLayerCellDim(VERTICAL, rowId, rowPosition,
 						dataCell.getRowPosition(), dataCell.getRowSpan() ));
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/cell/AlternatingRowConfigLabelAccumulator.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/AlternatingRowLabelContributor.java
index 1fc51ec0..c0691b3e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/cell/AlternatingRowConfigLabelAccumulator.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/AlternatingRowLabelContributor.java
@@ -11,12 +11,13 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.cell;
+package org.eclipse.statet.ecommons.waltable.grid;
 
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.grid.layer.config.DefaultRowStyleConfiguration;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.IConfigLabelAccumulator;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.grid.config.DefaultRowStyleConfiguration;
+import org.eclipse.statet.ecommons.waltable.layer.cell.CellLabelContributor;
 
 
 /**
@@ -25,14 +26,22 @@ import org.eclipse.statet.ecommons.waltable.layer.cell.IConfigLabelAccumulator;
  * 
  * @see DefaultRowStyleConfiguration
  */
-public class AlternatingRowConfigLabelAccumulator implements IConfigLabelAccumulator {
-
-	public static final String ODD_ROW_CONFIG_TYPE= "ODD_" + GridRegion.BODY; //$NON-NLS-1$
-
-	public static final String EVEN_ROW_CONFIG_TYPE= "EVEN_" + GridRegion.BODY; //$NON-NLS-1$
-
+@NonNullByDefault
+public class AlternatingRowLabelContributor implements CellLabelContributor {
+	
+	public static final String ODD_ROW_CONFIG_TYPE= "BODY_ODD_ROW"; //$NON-NLS-1$
+	
+	public static final String EVEN_ROW_CONFIG_TYPE= "BODY_EVEN_ROW"; //$NON-NLS-1$
+	
+	
+	
+	public AlternatingRowLabelContributor() {
+	}
+	
+	
 	@Override
-	public void accumulateConfigLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
+	public void addLabels(final LabelStack configLabels, final long columnPosition, final long rowPosition) {
 		configLabels.addLabel((rowPosition % 2 == 0 ? EVEN_ROW_CONFIG_TYPE : ODD_ROW_CONFIG_TYPE));
 	}
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/config/DefaultGridLayerConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/config/DefaultGridLayerConfiguration.java
index 670edf54..5153f016 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/config/DefaultGridLayerConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/config/DefaultGridLayerConfiguration.java
@@ -11,16 +11,16 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer.config;
+package org.eclipse.statet.ecommons.waltable.grid.config;
 
 import org.eclipse.statet.ecommons.waltable.config.AggregateConfiguration;
+import org.eclipse.statet.ecommons.waltable.core.layer.CompositeLayer;
 import org.eclipse.statet.ecommons.waltable.edit.config.DefaultEditBindings;
 import org.eclipse.statet.ecommons.waltable.edit.config.DefaultEditConfiguration;
 import org.eclipse.statet.ecommons.waltable.export.config.DefaultExportBindings;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.grid.cell.AlternatingRowConfigLabelAccumulator;
-import org.eclipse.statet.ecommons.waltable.grid.layer.GridLayer;
-import org.eclipse.statet.ecommons.waltable.layer.CompositeLayer;
+import org.eclipse.statet.ecommons.waltable.grid.AlternatingRowLabelContributor;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLayer;
 import org.eclipse.statet.ecommons.waltable.print.config.DefaultPrintBindings;
 
 
@@ -55,7 +55,7 @@ public class DefaultGridLayerConfiguration extends AggregateConfiguration {
 
 	protected void addAlternateRowColoringConfig(final CompositeLayer gridLayer) {
 		addConfiguration(new DefaultRowStyleConfiguration());
-		gridLayer.addConfigLabelAccumulatorForRegion(GridRegion.BODY, new AlternatingRowConfigLabelAccumulator());
+		gridLayer.addCellLabelContributor(GridLabels.BODY, new AlternatingRowLabelContributor());
 	}
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/config/DefaultRowStyleConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/config/DefaultRowStyleConfiguration.java
index 88350ce5..ae2e721c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/config/DefaultRowStyleConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/config/DefaultRowStyleConfiguration.java
@@ -11,17 +11,17 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer.config;
+package org.eclipse.statet.ecommons.waltable.grid.config;
 
 import org.eclipse.swt.graphics.Color;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractRegistryConfiguration;
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.grid.cell.AlternatingRowConfigLabelAccumulator;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.grid.AlternatingRowLabelContributor;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
@@ -34,20 +34,20 @@ public class DefaultRowStyleConfiguration extends AbstractRegistryConfiguration
 	public Color oddRowBgColor= GUIHelper.COLOR_WHITE;
 
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
+	public void configureRegistry(final ConfigRegistry configRegistry) {
 		configureOddRowStyle(configRegistry);
 		configureEvenRowStyle(configRegistry);
 	}
 
-	protected void configureOddRowStyle(final IConfigRegistry configRegistry) {
-		final Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR,  this.oddRowBgColor);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, AlternatingRowConfigLabelAccumulator.EVEN_ROW_CONFIG_TYPE);
+	protected void configureOddRowStyle(final ConfigRegistry configRegistry) {
+		final BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR,  this.oddRowBgColor);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, AlternatingRowLabelContributor.EVEN_ROW_CONFIG_TYPE);
 	}
 
-	protected void configureEvenRowStyle(final IConfigRegistry configRegistry) {
-		final Style cellStyle= new Style();
-		cellStyle.setAttributeValue(CellStyleAttributes.BACKGROUND_COLOR,  this.evenRowBgColor);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, AlternatingRowConfigLabelAccumulator.ODD_ROW_CONFIG_TYPE);
+	protected void configureEvenRowStyle(final ConfigRegistry configRegistry) {
+		final BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR,  this.evenRowBgColor);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle, DisplayMode.NORMAL, AlternatingRowLabelContributor.ODD_ROW_CONFIG_TYPE);
 	}
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/ClientAreaResizeCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/ClientAreaResizeCommand.java
index 07db388f..edc21952 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/ClientAreaResizeCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/ClientAreaResizeCommand.java
@@ -11,20 +11,25 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid;
+package org.eclipse.statet.ecommons.waltable.grid.core;
 
 import org.eclipse.swt.widgets.Scrollable;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
 
 
 /**
  * Command that gives the layers access to ClientArea and the Scrollable 
  */
+@NonNullByDefault
 public class ClientAreaResizeCommand extends AbstractContextFreeCommand {
 	
+	
 	/**
 	 * The {@link Scrollable}, normally the NatTable itself.
 	 */
@@ -35,22 +40,25 @@ public class ClientAreaResizeCommand extends AbstractContextFreeCommand {
 	 * Without using a GridLayer, this will be the client area of the scrollable.
 	 * On using a GridLayer this value will be overriden with the body region area.
 	 */
-	private LRectangle calcArea;
-
+	private @Nullable LRectangle calcArea;
+	
+	
 	public ClientAreaResizeCommand(final Scrollable scrollable) {
 		super();
 		this.scrollable= scrollable;
 	}
-
+	
+	
 	public Scrollable getScrollable() {
 		return this.scrollable;
 	}
 	
 	public LRectangle getCalcArea() {
-		if (this.calcArea == null) {
-			return SWTUtil.toNatTable(this.scrollable.getClientArea());
+		final LRectangle calcArea= this.calcArea;
+		if (calcArea == null) {
+			return SwtUtils.toNatTable(this.scrollable.getClientArea());
 		}
-		return this.calcArea;
+		return calcArea;
 	}
 	
 	public void setCalcArea(final LRectangle calcArea) {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/GridLabels.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/GridLabels.java
new file mode 100644
index 00000000..5a378d8b
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/GridLabels.java
@@ -0,0 +1,47 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.grid.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+
+/**
+ * A region is simply an area on the Grid.
+ * Diving the table/grid into regions makes it easier to manage areas with similar behavior.
+ * 
+ * For example all the cells in the column header are painted differently
+ * and can respond to sorting actions.
+ */
+@NonNullByDefault
+public interface GridLabels {
+	
+	
+	static final String CORNER= "CORNER"; //$NON-NLS-1$
+	static final String COLUMN_HEADER= "COLUMN_HEADER"; //$NON-NLS-1$
+	static final String ROW_HEADER= "ROW_HEADER"; //$NON-NLS-1$
+	
+	/* labeled header */
+	static final String COLUMN_HEADER_LABEL= COLUMN_HEADER + "_LABEL"; //$NON-NLS-1$
+	static final String ROW_HEADER_LABEL= ROW_HEADER + "_LABEL"; //$NON-NLS-1$
+	static final String HEADER_PLACEHOLDER= "HEADER_PLACEHOLDER"; //$NON-NLS-1$
+	
+	/* grouped column/row */
+	static final String COLUMN_GROUP_HEADER= "COLUMN_GROUP_HEADER"; //$NON-NLS-1$
+	static final String ROW_GROUP_HEADER= "ROW_GROUP_HEADER"; //$NON-NLS-1$
+	
+	static final String BODY= "BODY"; //$NON-NLS-1$
+	
+	static final String FILTER_ROW= "FILTER_ROW"; //$NON-NLS-1$
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/GridLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/GridLayer.java
index 2aa5e616..9725e276 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/GridLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/GridLayer.java
@@ -11,19 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer;
+package org.eclipse.statet.ecommons.waltable.grid.core;
 
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.CompositeLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
 import org.eclipse.statet.ecommons.waltable.export.ExportCommandHandler;
-import org.eclipse.statet.ecommons.waltable.grid.ClientAreaResizeCommand;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.grid.layer.config.DefaultGridLayerConfiguration;
-import org.eclipse.statet.ecommons.waltable.layer.CompositeLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.grid.config.DefaultGridLayerConfiguration;
 import org.eclipse.statet.ecommons.waltable.print.PrintCommandHandler;
-import org.eclipse.statet.ecommons.waltable.selection.SelectCellCommand;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectCellCommand;
 
 
 /**
@@ -32,13 +32,14 @@ import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
  * unlike the other layers. It simply delegates most functions to its child
  * layers.
  */
+@NonNullByDefault
 public class GridLayer extends CompositeLayer {
-
-	public GridLayer(final ILayer bodyLayer, final ILayer columnHeaderLayer, final ILayer rowHeaderLayer, final ILayer cornerLayer) {
+	
+	public GridLayer(final Layer bodyLayer, final Layer columnHeaderLayer, final Layer rowHeaderLayer, final Layer cornerLayer) {
 		this(bodyLayer, columnHeaderLayer, rowHeaderLayer, cornerLayer, true);
 	}
 	
-	public GridLayer(final ILayer bodyLayer, final ILayer columnHeaderLayer, final ILayer rowHeaderLayer, final ILayer cornerLayer, final boolean useDefaultConfiguration) {
+	public GridLayer(final Layer bodyLayer, final Layer columnHeaderLayer, final Layer rowHeaderLayer, final Layer cornerLayer, final boolean useDefaultConfiguration) {
 		super(2, 2);
 		
 		setBodyLayer(bodyLayer);
@@ -93,7 +94,7 @@ public class GridLayer extends CompositeLayer {
 	 * in the body.
 	 **/
 	@Override
-	protected boolean doCommandOnChildLayers(final ILayerCommand command) {
+	protected boolean doCommandOnChildLayers(final LayerCommand command) {
 		if (getBodyLayer().doCommand(command)) {
 			return true;
 		}
@@ -110,36 +111,36 @@ public class GridLayer extends CompositeLayer {
 	
 	// Sub-layer accessors
 	
-	public ILayer getCornerLayer() {
+	public Layer getCornerLayer() {
 		return getChildLayerByLayoutCoordinate(0, 0);
 	}
 	
-	public void setCornerLayer(final ILayer cornerLayer) {
-		setChildLayer(GridRegion.CORNER, cornerLayer, 0, 0);
+	public void setCornerLayer(final Layer cornerLayer) {
+		setChildLayer(GridLabels.CORNER, cornerLayer, 0, 0);
 	}
-
-	public ILayer getColumnHeaderLayer() {
+	
+	public Layer getColumnHeaderLayer() {
 		return getChildLayerByLayoutCoordinate(1, 0);
 	}
 	
-	public void setColumnHeaderLayer(final ILayer columnHeaderLayer) {
-		setChildLayer(GridRegion.COLUMN_HEADER, columnHeaderLayer, 1, 0);
+	public void setColumnHeaderLayer(final Layer columnHeaderLayer) {
+		setChildLayer(GridLabels.COLUMN_HEADER, columnHeaderLayer, 1, 0);
 	}
 	
-	public ILayer getRowHeaderLayer() {
+	public Layer getRowHeaderLayer() {
 		return getChildLayerByLayoutCoordinate(0, 1);
 	}
 	
-	public void setRowHeaderLayer(final ILayer rowHeaderLayer) {
-		setChildLayer(GridRegion.ROW_HEADER, rowHeaderLayer, 0, 1);
+	public void setRowHeaderLayer(final Layer rowHeaderLayer) {
+		setChildLayer(GridLabels.ROW_HEADER, rowHeaderLayer, 0, 1);
 	}
 	
-	public ILayer getBodyLayer() {
+	public Layer getBodyLayer() {
 		return getChildLayerByLayoutCoordinate(1, 1);
 	}
 	
-	public void setBodyLayer(final ILayer bodyLayer) {
-		setChildLayer(GridRegion.BODY, bodyLayer, 1, 1);
+	public void setBodyLayer(final Layer bodyLayer) {
+		setChildLayer(GridLabels.BODY, bodyLayer, 1, 1);
 		
 		//update the command handlers for auto resize because of the connection to the body layer stack
 //		unregisterCommandHandler(AutoResizePositionsCommand.class);
@@ -160,21 +161,23 @@ public class GridLayer extends CompositeLayer {
 	
 	
 	@Override
-	public boolean doCommand(final ILayerCommand command) {
-		if (command instanceof ClientAreaResizeCommand && command.convertToTargetLayer(this)) {
-			final ClientAreaResizeCommand clientAreaResizeCommand= (ClientAreaResizeCommand) command;
-			final LRectangle possibleArea= SWTUtil.toNatTable(clientAreaResizeCommand.getScrollable().getClientArea());
+	public boolean doCommand(final LayerCommand command) {
+		if (command instanceof ClientAreaResizeCommand) {
+			final ClientAreaResizeCommand resizeCommand= (ClientAreaResizeCommand)command;
+			final LRectangle possibleArea= SwtUtils.toNatTable(resizeCommand.getScrollable().getClientArea());
 			
 			//remove the column header height and the row header width from the client area to 
 			//ensure that only the body region is used for percentage calculation
 			final LRectangle rowLayerArea= getRowHeaderLayer().getClientAreaProvider().getClientArea();
 			final LRectangle columnLayerArea= getColumnHeaderLayer().getClientAreaProvider().getClientArea();
-			possibleArea.width= possibleArea.width - rowLayerArea.width;
-			possibleArea.height= possibleArea.height - columnLayerArea.height;
 			
-			clientAreaResizeCommand.setCalcArea(possibleArea);
+			resizeCommand.setCalcArea(new LRectangle(
+					possibleArea.x,
+					possibleArea.y,
+					possibleArea.width - rowLayerArea.width,
+					possibleArea.height - columnLayerArea.height ));
 		}
 		return super.doCommand(command);
 	}
-
-}
\ No newline at end of file
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/GridRegion.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/GridRegion.java
index badb668a..62c33263 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/GridRegion.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/GridRegion.java
@@ -11,7 +11,9 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid;
+package org.eclipse.statet.ecommons.waltable.grid.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 
 /**
@@ -21,19 +23,21 @@ package org.eclipse.statet.ecommons.waltable.grid;
  * For example all the cells in the column header are painted differently
  * and can respond to sorting actions.
  */
+@NonNullByDefault
 public interface GridRegion {
 	
-	public static final String CORNER= "CORNER"; //$NON-NLS-1$
-	public static final String COLUMN_HEADER= "COLUMN_HEADER"; //$NON-NLS-1$
-	public static final String COLUMN_GROUP_HEADER= "COLUMN_GROUP_HEADER"; //$NON-NLS-1$
-	public static final String ROW_HEADER= "ROW_HEADER"; //$NON-NLS-1$
-	public static final String ROW_GROUP_HEADER= "ROW_GROUP_HEADER"; //$NON-NLS-1$
-	public static final String COLUMN_HEADER_LABEL= COLUMN_HEADER + "_LABEL"; //$NON-NLS-1$
-	public static final String ROW_HEADER_LABEL= ROW_HEADER + "_LABEL"; //$NON-NLS-1$
-	public static final String HEADER_PLACEHOLDER= "HEADER_PLACEHOLDER"; //$NON-NLS-1$
 	
-	public static final String BODY= "BODY"; //$NON-NLS-1$
+	static final String CORNER= "CORNER"; //$NON-NLS-1$
+	static final String COLUMN_HEADER= "COLUMN_HEADER"; //$NON-NLS-1$
+	static final String COLUMN_GROUP_HEADER= "COLUMN_GROUP_HEADER"; //$NON-NLS-1$
+	static final String ROW_HEADER= "ROW_HEADER"; //$NON-NLS-1$
+	static final String ROW_GROUP_HEADER= "ROW_GROUP_HEADER"; //$NON-NLS-1$
+	static final String COLUMN_HEADER_LABEL= COLUMN_HEADER + "_LABEL"; //$NON-NLS-1$
+	static final String ROW_HEADER_LABEL= ROW_HEADER + "_LABEL"; //$NON-NLS-1$
+	static final String HEADER_PLACEHOLDER= "HEADER_PLACEHOLDER"; //$NON-NLS-1$
+	
+	static final String BODY= "BODY"; //$NON-NLS-1$
 	
-	public static final String FILTER_ROW= "FILTER_ROW"; //$NON-NLS-1$
+	static final String FILTER_ROW= "FILTER_ROW"; //$NON-NLS-1$
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/data/DefaultColumnHeaderDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/data/DefaultColumnHeaderDataProvider.java
new file mode 100644
index 00000000..e2b2cca7
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/data/DefaultColumnHeaderDataProvider.java
@@ -0,0 +1,64 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.grid.core.data;
+
+import org.eclipse.core.runtime.IProgressMonitor;
+
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+
+
+@NonNullByDefault
+public class DefaultColumnHeaderDataProvider implements DataProvider {
+	
+	
+	private final ImList<String> columnLabels;
+	
+	
+	public DefaultColumnHeaderDataProvider(final ImList<String> columnLabels) {
+		this.columnLabels= columnLabels;
+	}
+	
+	
+	@Override
+	public long getColumnCount() {
+		return this.columnLabels.size();
+	}
+	
+	@Override
+	public long getRowCount() {
+		return 1;
+	}
+	
+	/**
+	 * This class does not support multiple rows in the column header layer.
+	 */
+	@Override
+	public Object getDataValue(final long columnIndex, final long rowIndex, final int flags,
+			final @Nullable IProgressMonitor monitor) {
+		if (columnIndex < 0 || columnIndex >= this.columnLabels.size()) {
+			throw new IndexOutOfBoundsException();
+		}
+		return this.columnLabels.get((int)columnIndex);
+	}
+	
+	@Override
+	public void setDataValue(final long columnIndex, final long rowIndex, final @Nullable Object newValue) {
+		throw new UnsupportedOperationException();
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DefaultCornerDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/data/DefaultCornerDataProvider.java
index a6bc893a..adedd809 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DefaultCornerDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/data/DefaultCornerDataProvider.java
@@ -11,25 +11,29 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.data;
+package org.eclipse.statet.ecommons.waltable.grid.core.data;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
 
-public class DefaultCornerDataProvider implements IDataProvider {
+
+@NonNullByDefault
+public class DefaultCornerDataProvider implements DataProvider {
 	
 	
-	private final IDataProvider columnHeaderDataProvider;
-	private final IDataProvider rowHeaderDataProvider;
+	private final DataProvider columnHeaderDataProvider;
+	private final DataProvider rowHeaderDataProvider;
 	
 	
-	public DefaultCornerDataProvider(final IDataProvider columnHeaderDataProvider, final IDataProvider rowHeaderDataProvider) {
+	public DefaultCornerDataProvider(final DataProvider columnHeaderDataProvider, final DataProvider rowHeaderDataProvider) {
 		this.columnHeaderDataProvider= columnHeaderDataProvider;
 		this.rowHeaderDataProvider= rowHeaderDataProvider;
 	}
 	
+	
 	@Override
 	public long getColumnCount() {
 		return this.rowHeaderDataProvider.getColumnCount();
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DefaultRowHeaderDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/data/DefaultRowHeaderDataProvider.java
index dac2ff8e..cba07dfb 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DefaultRowHeaderDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/data/DefaultRowHeaderDataProvider.java
@@ -11,20 +11,23 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.data;
+package org.eclipse.statet.ecommons.waltable.grid.core.data;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
 
-public class DefaultRowHeaderDataProvider implements IDataProvider {
+
+@NonNullByDefault
+public class DefaultRowHeaderDataProvider implements DataProvider {
 	
 	
-	protected final IDataProvider bodyDataProvider;
+	private final DataProvider bodyDataProvider;
 	
 	
-	public DefaultRowHeaderDataProvider(final IDataProvider bodyDataProvider) {
+	public DefaultRowHeaderDataProvider(final DataProvider bodyDataProvider) {
 		this.bodyDataProvider= bodyDataProvider;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/ExtColumnHeaderLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/labeled/ExtColumnHeaderLayer.java
index b52a7c2a..c47cb1ff 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/ExtColumnHeaderLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/labeled/ExtColumnHeaderLayer.java
@@ -12,25 +12,28 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.labeled;
+package org.eclipse.statet.ecommons.waltable.grid.core.labeled;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.grid.layer.PlaceholderLayer;
-import org.eclipse.statet.ecommons.waltable.layer.CompositeLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.CompositeLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
+import org.eclipse.statet.ecommons.waltable.grid.core.layers.PlaceholderLayer;
 
+
+@NonNullByDefault
 public class ExtColumnHeaderLayer extends CompositeLayer {
 	
 	
-	public ExtColumnHeaderLayer(final ILayer columnHeaderLayer) {
+	public ExtColumnHeaderLayer(final Layer columnHeaderLayer) {
 		super(1, 2);
 		
-		setChildLayer(GridRegion.COLUMN_HEADER, columnHeaderLayer, 0, 0);
-		setChildLayer(GridRegion.HEADER_PLACEHOLDER, new PlaceholderLayer(columnHeaderLayer, null,
+		setChildLayer(GridLabels.COLUMN_HEADER, columnHeaderLayer, 0, 0);
+		setChildLayer(GridLabels.HEADER_PLACEHOLDER, new PlaceholderLayer(columnHeaderLayer, null,
 				false, columnHeaderLayer.getLayerPainter() ), 0, 1);
 	}
 	
@@ -42,8 +45,7 @@ public class ExtColumnHeaderLayer extends CompositeLayer {
 	
 	
 	public void setSpaceSize(final int pixel) {
-		((PlaceholderLayer) getChildByLabel(GridRegion.HEADER_PLACEHOLDER).layer)
-				.setSize(pixel);
+		((PlaceholderLayer)getChildByLabel(GridLabels.HEADER_PLACEHOLDER).layer).setSize(pixel);
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/ExtGridLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/labeled/ExtGridLayer.java
index ba7dd6d0..2ae44679 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/ExtGridLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/labeled/ExtGridLayer.java
@@ -12,32 +12,37 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.labeled;
+package org.eclipse.statet.ecommons.waltable.grid.core.labeled;
 
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.grid.layer.GridLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLayer;
 
+
+@NonNullByDefault
 public class ExtGridLayer extends GridLayer {
 	
 	
-	public static final String EXT_COLUMN_HEADER= "EXT_" + GridRegion.COLUMN_HEADER; //$NON-NLS-1$
-	public static final String EXT_ROW_HEADER= "EXT_" + GridRegion.ROW_HEADER; //$NON-NLS-1$
+	public static final String EXT_COLUMN_HEADER= "EXT_" + GridLabels.COLUMN_HEADER; //$NON-NLS-1$
+	public static final String EXT_ROW_HEADER= "EXT_" + GridLabels.ROW_HEADER; //$NON-NLS-1$
 	
 	
-	public ExtGridLayer(final ILayer bodyLayer, final ILayer columnHeaderLayer, final ILayer rowHeaderLayer, final ILayer cornerLayer, final boolean useDefaultConfiguration) {
+	public ExtGridLayer(final Layer bodyLayer,
+			final Layer columnHeaderLayer, final Layer rowHeaderLayer, final Layer cornerLayer,
+			final boolean useDefaultConfiguration) {
 		super(bodyLayer, columnHeaderLayer, rowHeaderLayer, cornerLayer, useDefaultConfiguration);
 	}
 	
 	
 	@Override
-	public void setColumnHeaderLayer(final ILayer columnHeaderLayer) {
+	public void setColumnHeaderLayer(final Layer columnHeaderLayer) {
 		setChildLayer(EXT_COLUMN_HEADER, columnHeaderLayer, 1, 0);
 	}
 	
 	@Override
-	public void setRowHeaderLayer(final ILayer rowHeaderLayer) {
+	public void setRowHeaderLayer(final Layer rowHeaderLayer) {
 		setChildLayer(EXT_ROW_HEADER, rowHeaderLayer, 0, 1);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/ExtRowHeaderLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/labeled/ExtRowHeaderLayer.java
index 5b575dc0..00624a97 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/labeled/ExtRowHeaderLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/labeled/ExtRowHeaderLayer.java
@@ -12,25 +12,28 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.labeled;
+package org.eclipse.statet.ecommons.waltable.grid.core.labeled;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.grid.layer.PlaceholderLayer;
-import org.eclipse.statet.ecommons.waltable.layer.CompositeLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.CompositeLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
+import org.eclipse.statet.ecommons.waltable.grid.core.layers.PlaceholderLayer;
 
+
+@NonNullByDefault
 public class ExtRowHeaderLayer extends CompositeLayer {
 	
 	
-	public ExtRowHeaderLayer(final ILayer rowHeaderLayer) {
+	public ExtRowHeaderLayer(final Layer rowHeaderLayer) {
 		super(2, 1);
 		
-		setChildLayer(GridRegion.ROW_HEADER, rowHeaderLayer, 0, 0);
-		setChildLayer(GridRegion.HEADER_PLACEHOLDER, new PlaceholderLayer(null, rowHeaderLayer,
+		setChildLayer(GridLabels.ROW_HEADER, rowHeaderLayer, 0, 0);
+		setChildLayer(GridLabels.HEADER_PLACEHOLDER, new PlaceholderLayer(null, rowHeaderLayer,
 				false, rowHeaderLayer.getLayerPainter() ), 1, 0);
 	}
 	
@@ -42,8 +45,7 @@ public class ExtRowHeaderLayer extends CompositeLayer {
 	
 	
 	public void setSpaceSize(final int pixel) {
-		((PlaceholderLayer) getChildByLabel(GridRegion.HEADER_PLACEHOLDER).layer)
-				.setSize(pixel);
+		((PlaceholderLayer)getChildByLabel(GridLabels.HEADER_PLACEHOLDER).layer).setSize(pixel);
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/labeled/LabelCornerLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/labeled/LabelCornerLayer.java
new file mode 100644
index 00000000..b9598154
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/labeled/LabelCornerLayer.java
@@ -0,0 +1,126 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.grid.core.labeled;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import org.eclipse.core.runtime.IProgressMonitor;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.core.layer.BasicLayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.BasicLayerCellDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
+import org.eclipse.statet.ecommons.waltable.grid.core.layers.CornerLayer;
+
+
+@NonNullByDefault
+public class LabelCornerLayer extends CornerLayer {
+	
+	
+	private final @Nullable DataProvider columnHeaderLabelProvider;
+	private final @Nullable DataProvider rowHeaderLabelProvider;
+	
+	
+	/**
+	 * @param baseLayer
+	 *            The data provider for this layer
+	 * @param horizontalLayerDependency
+	 *            The layer to link the horizontal dimension to, typically the row header layer
+	 * @param verticalLayerDependency
+	 *            The layer to link the vertical dimension to, typically the column header layer
+	 * @param useDefaultConfiguration
+	 *            If default configuration should be applied to this layer (at moment none)
+	 * @param layerPainter
+	 *            The painter for this layer or <code>null</code> to use the painter of the base layer
+	 */
+	public LabelCornerLayer(final Layer baseLayer,
+			final Layer horizontalLayerDependency, final Layer verticalLayerDependency,
+			final @Nullable DataProvider columnHeaderLabelProvider,
+			final @Nullable DataProvider rowHeaderLabelProvider,
+			final boolean useDefaultConfiguration,
+			final LayerPainter layerPainter) {
+		super(baseLayer, horizontalLayerDependency, verticalLayerDependency,
+				useDefaultConfiguration, layerPainter );
+		
+		this.columnHeaderLabelProvider= columnHeaderLabelProvider;
+		this.rowHeaderLabelProvider= rowHeaderLabelProvider;
+	}
+	
+	
+	@Override
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+		final LayerDim hDim= getDim(HORIZONTAL);
+		final LayerDim vDim= getDim(VERTICAL);
+		final long columnId= hDim.getPositionId(columnPosition, columnPosition);
+		final long rowId= vDim.getPositionId(rowPosition, rowPosition);
+		
+		final long columnCount= getColumnCount();
+		final long rowCount= getRowCount();
+		if (rowPosition < rowCount - 1) {
+			return new BasicLayerCell(this,
+					new BasicLayerCellDim(HORIZONTAL, columnId, columnPosition, 0, columnCount),
+					new BasicLayerCellDim(VERTICAL, rowId, rowPosition) ) {
+				@Override
+				public LabelStack getLabels() {
+					return new LabelStack(GridLabels.COLUMN_HEADER_LABEL);
+				}
+				@Override
+				public @Nullable Object getDataValue(final int flags, final @Nullable IProgressMonitor monitor) {
+					final var labelProvider= LabelCornerLayer.this.columnHeaderLabelProvider;
+					return (labelProvider != null) ? 
+							labelProvider.getDataValue(0, getRowPosition(), flags, monitor) :
+							""; //$NON-NLS-1$
+				}
+			};
+		}
+		else if (columnPosition < columnCount - 1) {
+			return new BasicLayerCell(this,
+					new BasicLayerCellDim(HORIZONTAL, columnId, columnPosition),
+					new BasicLayerCellDim(VERTICAL, rowId, rowPosition) ) {
+				@Override
+				public LabelStack getLabels() {
+					return new LabelStack(GridLabels.ROW_HEADER_LABEL);
+				}
+				@Override
+				public @Nullable Object getDataValue(final int flags, final @Nullable IProgressMonitor monitor) {
+					final var labelProvider= LabelCornerLayer.this.rowHeaderLabelProvider;
+					return (labelProvider != null) ? 
+							labelProvider.getDataValue(getColumnPosition(), 0, flags, monitor) :
+							""; //$NON-NLS-1$
+				}
+			};
+		}
+		else {
+			return new BasicLayerCell(this,
+					new BasicLayerCellDim(HORIZONTAL, columnId, columnPosition),
+					new BasicLayerCellDim(VERTICAL, rowId, rowPosition) ) {
+				@Override
+				public LabelStack getLabels() {
+					return new LabelStack(GridLabels.HEADER_PLACEHOLDER);
+				}
+			};
+		}
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/AbstractPositionHeaderLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/AbstractPositionHeaderLayer.java
index c7183752..849426f0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/AbstractPositionHeaderLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/AbstractPositionHeaderLayer.java
@@ -11,27 +11,32 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer;
+package org.eclipse.statet.ecommons.waltable.grid.core.layers;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.LayerUtil;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ForwardLayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCellDim;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerUtils;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 
 
 /**
  * Responsible for rendering, event handling etc on the column/row headers.
  */
+@NonNullByDefault
 public class AbstractPositionHeaderLayer extends DimensionallyDependentLayer {
 	
 	
@@ -51,40 +56,35 @@ public class AbstractPositionHeaderLayer extends DimensionallyDependentLayer {
 	 * @param layerPainter
 	 *            The painter for this layer or <code>null</code> to use the painter of the base layer
 	 */
-	public AbstractPositionHeaderLayer(final ILayer baseLayer, final Orientation orientation,
-			final ILayer contentLayerDependency,
+	public AbstractPositionHeaderLayer(final Layer baseLayer, final Orientation orientation,
+			final Layer contentLayerDependency,
 			final SelectionLayer selectionLayer, final String fullySelectedLabel,
-			final ILayerPainter layerPainter) {
+			final LayerPainter layerPainter) {
 		super(baseLayer,
 				(orientation == HORIZONTAL) ? contentLayerDependency : baseLayer,
-				(orientation == VERTICAL) ? contentLayerDependency : baseLayer );
-		if (selectionLayer == null) {
-			throw new NullPointerException("selectionLayer"); //$NON-NLS-1$
-		}
-		
-		this.headerOrientation= orientation;
-		this.selectionLayer= selectionLayer;
-		this.fullySelectedLabel= fullySelectedLabel;
-		
-		this.layerPainter= layerPainter;
+				(orientation == VERTICAL) ? contentLayerDependency : baseLayer,
+				layerPainter );
+		this.headerOrientation= nonNullAssert(orientation);
+		this.selectionLayer= nonNullAssert(selectionLayer);
+		this.fullySelectedLabel= nonNullAssert(fullySelectedLabel);
 	}
 	
 	
 	@Override
-	protected ILayerCell createCell(final ILayerCellDim hDim, final ILayerCellDim vDim, final ILayerCell underlyingCell) {
+	protected LayerCell createCell(final LayerCellDim hDim, final LayerCellDim vDim, final LayerCell underlyingCell) {
 		return new ForwardLayerCell(this, hDim, vDim, underlyingCell) {
 			
 			@Override
 			public DisplayMode getDisplayMode() {
 				if (isSelected(getDim(AbstractPositionHeaderLayer.this.headerOrientation))) {
-					return DisplayMode.SELECT;
+					return DisplayMode.SELECTED;
 				}
 				return super.getDisplayMode();
 			}
 			
 			@Override
-			public LabelStack getConfigLabels() {
-				final LabelStack configLabels= super.getConfigLabels();
+			public LabelStack getLabels() {
+				final LabelStack configLabels= super.getLabels();
 				
 				if (isFullySelected(getDim(AbstractPositionHeaderLayer.this.headerOrientation))) {
 					configLabels.addLabel(AbstractPositionHeaderLayer.this.fullySelectedLabel);
@@ -96,11 +96,11 @@ public class AbstractPositionHeaderLayer extends DimensionallyDependentLayer {
 		};
 	}
 	
-	protected boolean isSelected(final ILayerCellDim dim) {
-		final ILayerDim layerDim= getDim(this.headerOrientation);
+	protected boolean isSelected(final LayerCellDim dim) {
+		final LayerDim layerDim= getDim(this.headerOrientation);
 		final long position= dim.getPosition();
 		if (this.selectionLayer.isPositionSelected(this.headerOrientation,
-				LayerUtil.convertPosition(layerDim, position, position,
+				LayerUtils.convertPosition(layerDim, position, position,
 						this.selectionLayer.getDim(this.headerOrientation) ) )) {
 			return true;
 		}
@@ -110,7 +110,7 @@ public class AbstractPositionHeaderLayer extends DimensionallyDependentLayer {
 			for (; iPosition < endPosition; iPosition++) {
 				if (iPosition != position
 						&& this.selectionLayer.isPositionSelected(this.headerOrientation,
-								LayerUtil.convertPosition(layerDim, position, iPosition,
+								LayerUtils.convertPosition(layerDim, position, iPosition,
 										this.selectionLayer.getDim(this.headerOrientation) ))) {
 					return true;
 				}
@@ -119,11 +119,11 @@ public class AbstractPositionHeaderLayer extends DimensionallyDependentLayer {
 		return false;
 	}
 	
-	protected boolean isFullySelected(final ILayerCellDim dim) {
-		final ILayerDim layerDim= getDim(this.headerOrientation);
+	protected boolean isFullySelected(final LayerCellDim dim) {
+		final LayerDim layerDim= getDim(this.headerOrientation);
 		final long position= dim.getPosition();
 		if (!this.selectionLayer.isPositionFullySelected(this.headerOrientation,
-				LayerUtil.convertPosition(layerDim, position, position,
+				LayerUtils.convertPosition(layerDim, position, position,
 						this.selectionLayer.getDim(this.headerOrientation)) )) {
 			return false;
 		}
@@ -133,7 +133,7 @@ public class AbstractPositionHeaderLayer extends DimensionallyDependentLayer {
 			for (; iPosition < endPosition; iPosition++) {
 				if (iPosition != position
 						&& !this.selectionLayer.isPositionFullySelected(this.headerOrientation,
-						LayerUtil.convertPosition(layerDim, position, iPosition,
+						LayerUtils.convertPosition(layerDim, position, iPosition,
 								this.selectionLayer.getDim(this.headerOrientation) ))) {
 					return false;
 				}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/ColumnHeaderLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/ColumnHeaderLayer.java
index 8f226adc..209d6d96 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/ColumnHeaderLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/ColumnHeaderLayer.java
@@ -11,21 +11,24 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer;
+package org.eclipse.statet.ecommons.waltable.grid.core.layers;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
+import org.eclipse.statet.ecommons.waltable.core.swt.painters.CellLayerPainter;
 import org.eclipse.statet.ecommons.waltable.layer.config.DefaultColumnHeaderLayerConfiguration;
-import org.eclipse.statet.ecommons.waltable.painter.layer.CellLayerPainter;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 import org.eclipse.statet.ecommons.waltable.style.SelectionStyleLabels;
 
 
 /**
  * Responsible for rendering, event handling etc on the column headers.
  */
+@NonNullByDefault
 public class ColumnHeaderLayer extends AbstractPositionHeaderLayer {
 	
 	
@@ -39,11 +42,11 @@ public class ColumnHeaderLayer extends AbstractPositionHeaderLayer {
 	 * @param selectionLayer
 	 *            The selection layer required to respond to selection events
 	 */
-	public ColumnHeaderLayer(final ILayer baseLayer, final ILayer horizontalLayerDependency, final SelectionLayer selectionLayer) {
+	public ColumnHeaderLayer(final Layer baseLayer, final Layer horizontalLayerDependency, final SelectionLayer selectionLayer) {
 		this(baseLayer, horizontalLayerDependency, selectionLayer, true);
 	}
 	
-	public ColumnHeaderLayer(final ILayer baseLayer, final ILayer horizontalLayerDependency, final SelectionLayer selectionLayer, final boolean useDefaultConfiguration) {
+	public ColumnHeaderLayer(final Layer baseLayer, final Layer horizontalLayerDependency, final SelectionLayer selectionLayer, final boolean useDefaultConfiguration) {
 		this(baseLayer, horizontalLayerDependency, selectionLayer, useDefaultConfiguration, new CellLayerPainter());
 	}
 	
@@ -59,8 +62,9 @@ public class ColumnHeaderLayer extends AbstractPositionHeaderLayer {
 	 * @param layerPainter
 	 *            The painter for this layer or <code>null</code> to use the painter of the base layer
 	 */
-	public ColumnHeaderLayer(final ILayer baseLayer, final ILayer horizontalLayerDependency,
-			final SelectionLayer selectionLayer, final boolean useDefaultConfiguration, final ILayerPainter layerPainter) {
+	public ColumnHeaderLayer(final Layer baseLayer, final Layer horizontalLayerDependency,
+			final SelectionLayer selectionLayer, final boolean useDefaultConfiguration,
+			final LayerPainter layerPainter) {
 		super(baseLayer, HORIZONTAL, horizontalLayerDependency,
 				selectionLayer, SelectionStyleLabels.COLUMN_FULLY_SELECTED_STYLE,
 				layerPainter );
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/CornerLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/CornerLayer.java
new file mode 100644
index 00000000..09c50f36
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/CornerLayer.java
@@ -0,0 +1,70 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.grid.core.layers;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.layer.BasicLayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.BasicLayerCellDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
+
+
+/**
+ * Layer for the top left header corner of the grid layer
+ */
+@NonNullByDefault
+public class CornerLayer extends DimensionallyDependentLayer {
+	
+	
+	/**
+	 * @param baseLayer
+	 *            The data provider for this layer
+	 * @param horizontalLayerDependency
+	 *            The layer to link the horizontal dimension to, typically the row header layer
+	 * @param verticalLayerDependency
+	 *            The layer to link the vertical dimension to, typically the column header layer
+	 * @param useDefaultConfiguration
+	 *            If default configuration should be applied to this layer (at moment none)
+	 * @param layerPainter
+	 *            The painter for this layer or <code>null</code> to use the painter of the base layer
+	 */
+	public CornerLayer(final Layer baseLayer,
+			final Layer horizontalLayerDependency, final Layer verticalLayerDependency,
+			final boolean useDefaultConfiguration,
+			final LayerPainter layerPainter) {
+		super(baseLayer, horizontalLayerDependency, verticalLayerDependency, layerPainter);
+	}
+	
+	
+	@Override
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+		final LayerDim hDim= getDim(HORIZONTAL);
+		final LayerDim vDim= getDim(VERTICAL);
+		final long columnId= hDim.getPositionId(columnPosition, columnPosition);
+		final long rowId= vDim.getPositionId(rowPosition, rowPosition);
+		
+		return new BasicLayerCell(this,
+				new BasicLayerCellDim(HORIZONTAL, columnId,
+						columnPosition, 0, hDim.getPositionCount() ),
+				new BasicLayerCellDim(VERTICAL, rowId,
+						rowPosition, 0, getVerticalLayerDependency().getRowCount()) );
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/DefaultColumnHeaderDataLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/DefaultColumnHeaderDataLayer.java
index 9b91c1fe..7062a6a6 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/DefaultColumnHeaderDataLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/DefaultColumnHeaderDataLayer.java
@@ -11,17 +11,20 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer;
+package org.eclipse.statet.ecommons.waltable.grid.core.layers;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionId;
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionId;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.data.core.DataLayer;
 
+
+@NonNullByDefault
 public class DefaultColumnHeaderDataLayer extends DataLayer {
 	
 	
-	public DefaultColumnHeaderDataLayer(final IDataProvider columnHeaderDataProvider) {
+	public DefaultColumnHeaderDataLayer(final DataProvider columnHeaderDataProvider) {
 		super(columnHeaderDataProvider,
 				PositionId.BODY_CAT, 100,
 				PositionId.HEADER_CAT, 20);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/DefaultRowHeaderDataLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/DefaultRowHeaderDataLayer.java
index df5cc511..208824ff 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/DefaultRowHeaderDataLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/DefaultRowHeaderDataLayer.java
@@ -11,17 +11,20 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer;
+package org.eclipse.statet.ecommons.waltable.grid.core.layers;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionId;
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionId;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.data.core.DataLayer;
 
+
+@NonNullByDefault
 public class DefaultRowHeaderDataLayer extends DataLayer {
 	
 	
-	public DefaultRowHeaderDataLayer(final IDataProvider rowHeaderDataProvider) {
+	public DefaultRowHeaderDataLayer(final DataProvider rowHeaderDataProvider) {
 		super(rowHeaderDataProvider,
 				PositionId.HEADER_CAT, 40,
 				PositionId.BODY_CAT, 40);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/DimensionallyDependentLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/DimensionallyDependentLayer.java
index 68ee02aa..8b93f5d0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/DimensionallyDependentLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/DimensionallyDependentLayer.java
@@ -12,23 +12,30 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer;
+package org.eclipse.statet.ecommons.waltable.grid.core.layers;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullLateInit;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
-import org.eclipse.statet.ecommons.waltable.layer.ForwardLayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.TransformLayer;
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.TransformLayer;
 
 
 /**
@@ -50,18 +57,19 @@ import org.eclipse.statet.ecommons.waltable.layer.TransformLayer;
  * ILayer rowHeaderLayer= new DimensionallyDependentLayer(rowHeaderColumnDataLayer, bodyLayer, rowHeaderColumnDataLayer);
  * </pre>
  */
-public class DimensionallyDependentLayer extends TransformLayer {
+@NonNullByDefault
+public class DimensionallyDependentLayer extends TransformLayer<ForwardLayerDim<? extends DimensionallyDependentLayer>> {
 	
 	
 	protected static class Dim extends ForwardLayerDim<DimensionallyDependentLayer> {
 		
 		
-		public Dim(final DimensionallyDependentLayer layer, final ILayerDim underlyingDim) {
+		public Dim(final DimensionallyDependentLayer layer, final LayerDim underlyingDim) {
 			super(layer, underlyingDim);
 		}
 		
 		
-		protected ILayerDim getBaseDim() {
+		protected LayerDim getBaseDim() {
 			return this.layer.getBaseLayer().getDim(this.orientation);
 		}
 		
@@ -72,14 +80,14 @@ public class DimensionallyDependentLayer extends TransformLayer {
 			final long underlyingPosition= getBaseDim().getPositionById(id);
 			
 			if (underlyingPosition == POSITION_NA) {
-				throw PositionOutOfBoundsException.position(position, getOrientation());
+				throw new PositionOutOfBoundsException(position, getOrientation());
 			}
 			
 			return underlyingPosition;
 		}
 		
 		@Override
-		public long underlyingToLocalPosition(final ILayerDim sourceUnderlyingDim,
+		public long underlyingToLocalPosition(final LayerDim sourceUnderlyingDim,
 				final long underlyingPosition) {
 			if (sourceUnderlyingDim != getBaseDim()) {
 				throw new IllegalArgumentException("underlyingLayer"); //$NON-NLS-1$
@@ -89,7 +97,7 @@ public class DimensionallyDependentLayer extends TransformLayer {
 		}
 		
 		@Override
-		public List<LRange> underlyingToLocalPositions(final ILayerDim sourceUnderlyingDim,
+		public List<LRange> underlyingToLocalPositions(final LayerDim sourceUnderlyingDim,
 				final Collection<LRange> underlyingPositions) {
 			if (sourceUnderlyingDim != getBaseDim()) {
 				throw new IllegalArgumentException("underlyingLayer"); //$NON-NLS-1$
@@ -119,22 +127,23 @@ public class DimensionallyDependentLayer extends TransformLayer {
 			final long position= this.underlyingDim.getPositionById(id);
 			
 			if (underlyingPosition == POSITION_NA) {
-				throw PositionOutOfBoundsException.underlyingPosition(underlyingPosition);
+				throw new PositionOutOfBoundsException("underlyingPosition",
+						underlyingPosition, getOrientation() );
 			}
 			
 			return position;
 		}
 		
 		@Override
-		public List<ILayerDim> getUnderlyingDimsByPosition(final long position) {
-			return Collections.<ILayerDim>singletonList(getBaseDim());
+		public ImList<LayerDim> getUnderlyingDimsByPosition(final long position) {
+			return ImCollections.newList(getBaseDim());
 		}
 		
 	}
 	
 	
-	private ILayer horizontalLayerDependency;
-	private ILayer verticalLayerDependency;
+	private Layer horizontalLayerDependency= nonNullLateInit();
+	private Layer verticalLayerDependency= nonNullLateInit();
 	
 	
 	/**
@@ -144,48 +153,63 @@ public class DimensionallyDependentLayer extends TransformLayer {
 	 * @param horizontalLayerDependency the layer, the horizontal dimension is linked to
 	 * @param verticalLayerDependency the layer, the vertical dimension is linked to
 	 */
-	public DimensionallyDependentLayer(final ILayer baseLayer,
-			final ILayer horizontalLayerDependency, final ILayer verticalLayerDependency) {
-		super(baseLayer);
+	public DimensionallyDependentLayer(final Layer baseLayer,
+			final Layer horizontalLayerDependency, final Layer verticalLayerDependency,
+			final @Nullable LayerPainter layerPainter) {
+		super(baseLayer, layerPainter);
+		
+		this.horizontalLayerDependency= horizontalLayerDependency;
+		this.verticalLayerDependency= verticalLayerDependency;
 		
-		setHorizontalLayerDependency(horizontalLayerDependency);
-		setVerticalLayerDependency(verticalLayerDependency);
+		init();
 	}
 	
 	/**
-	 * Creates a new DimensionallyDependentLayer. The horizontal and vertical layer dependency must be set
-	 * by calling {@link #init(ILayer, ILayer)} before the layer is used.
+	 * Creates a new DimensionallyDependentLayer.
 	 * 
 	 * @param baseLayer the underlying base layer
+	 * @param horizontalLayerDependency the layer, the horizontal dimension is linked to
+	 * @param verticalLayerDependency the layer, the vertical dimension is linked to
 	 */
-	protected DimensionallyDependentLayer(final ILayer baseLayer) {
-		super(baseLayer);
+	public DimensionallyDependentLayer(final Layer baseLayer,
+			final Layer horizontalLayerDependency, final Layer verticalLayerDependency) {
+		this(baseLayer, horizontalLayerDependency, verticalLayerDependency, null);
 	}
 	
+	/**
+	 * Creates a new DimensionallyDependentLayer. The horizontal and vertical layer dependency must be set
+	 * by calling {@link #init(Layer, Layer)} before the layer is used.
+	 * 
+	 * @param baseLayer the underlying base layer
+	 */
+	protected DimensionallyDependentLayer(final Layer baseLayer,
+			final @Nullable LayerPainter layerPainter) {
+		super(baseLayer, layerPainter);
+	}
 	
 	@Override
-	protected void initDims() {
+	protected void init() {
 		if (this.horizontalLayerDependency == null || this.verticalLayerDependency == null) {
 			return;
 		}
-		
-		for (final Orientation orientation : Orientation.values()) {
-			final ILayer dependency= getLayerDependency(orientation);
-			final ILayerDim dim;
-			if (dependency == getBaseLayer()) {
-				dim= new ForwardLayerDim<>(this, dependency.getDim(orientation));
-			}
-			else {
-				dim= new Dim(this, dependency.getDim(orientation));
-			}
-			setDim(dim);
+		super.init();
+	}
+	
+	@Override
+	protected ForwardLayerDim<? extends DimensionallyDependentLayer> createDim(final Orientation orientation) {
+		final Layer dependency= getLayerDependency(orientation);
+		if (dependency == getBaseLayer()) {
+			return new ForwardLayerDim<>(this, dependency.getDim(orientation));
+		}
+		else {
+			return new Dim(this, dependency.getDim(orientation));
 		}
 	}
 	
 	
 	// Dependent layer accessors
 	
-	protected void setHorizontalLayerDependency(final ILayer horizontalLayerDependency) {
+	protected void setHorizontalLayerDependency(final Layer horizontalLayerDependency) {
 		this.horizontalLayerDependency= horizontalLayerDependency;
 		
 //		horizontalLayerDependency.addLayerListener(new ILayerListener() {
@@ -198,10 +222,10 @@ public class DimensionallyDependentLayer extends TransformLayer {
 //
 //		});
 		
-		initDims();
+		init();
 	}
 
-	protected void setVerticalLayerDependency(final ILayer verticalLayerDependency) {
+	protected void setVerticalLayerDependency(final Layer verticalLayerDependency) {
 		this.verticalLayerDependency= verticalLayerDependency;
 
 //		verticalLayerDependency.addLayerListener(new ILayerListener() {
@@ -214,29 +238,29 @@ public class DimensionallyDependentLayer extends TransformLayer {
 //
 //		});
 		
-		initDims();
+		init();
 	}
 	
-	public ILayer getHorizontalLayerDependency() {
+	public Layer getHorizontalLayerDependency() {
 		return this.horizontalLayerDependency;
 	}
 	
-	public ILayer getVerticalLayerDependency() {
+	public Layer getVerticalLayerDependency() {
 		return this.verticalLayerDependency;
 	}
 	
-	public ILayer getLayerDependency(final Orientation orientation) {
+	public Layer getLayerDependency(final Orientation orientation) {
 		return (orientation == HORIZONTAL) ? this.horizontalLayerDependency : this.verticalLayerDependency;
 	}
 	
-	public ILayer getBaseLayer() {
+	public Layer getBaseLayer() {
 		return getUnderlyingLayer();
 	}
 	
 	// Commands
 	
 	@Override
-	public boolean doCommand(final ILayerCommand command) {
+	public boolean doCommand(final LayerCommand command) {
 		if (super.doCommand(command)) {
 			return true;
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/PlaceholderLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/PlaceholderLayer.java
index 86398bb5..7850620c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/PlaceholderLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/PlaceholderLayer.java
@@ -12,32 +12,36 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer;
+package org.eclipse.statet.ecommons.waltable.grid.core.layers;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionId;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
-import org.eclipse.statet.ecommons.waltable.layer.AbstractLayer;
-import org.eclipse.statet.ecommons.waltable.layer.DataDim;
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.LayerCellDim;
-import org.eclipse.statet.ecommons.waltable.painter.layer.CellLayerPainter;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionId;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.layer.AbstractLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.BasicLayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.BasicLayerCellDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
+import org.eclipse.statet.ecommons.waltable.core.swt.painters.CellLayerPainter;
+import org.eclipse.statet.ecommons.waltable.data.core.DataLayer;
+import org.eclipse.statet.ecommons.waltable.data.core.DataLayerDim;
 
+
+@NonNullByDefault
 public class PlaceholderLayer extends DimensionallyDependentLayer {
 	
 	
-	private static class DummyLayer extends AbstractLayer implements ILayer {
+	private static class DummyLayer extends AbstractLayer<DataLayerDim<DummyLayer>> implements Layer {
 		
-		private static class Dim extends DataDim<DummyLayer> {
+		private static class Dim extends DataLayerDim<DummyLayer> {
 			
 			
 			public Dim(final DummyLayer layer, final Orientation orientation, final long catId) {
@@ -64,7 +68,7 @@ public class PlaceholderLayer extends DimensionallyDependentLayer {
 			@Override
 			public long getPositionStart(final long position) {
 				if (position != 0) {
-					throw PositionOutOfBoundsException.position(position, getOrientation());
+					throw new PositionOutOfBoundsException(position, getOrientation());
 				}
 				return 0;
 			}
@@ -72,7 +76,7 @@ public class PlaceholderLayer extends DimensionallyDependentLayer {
 			@Override
 			public int getPositionSize(final long position) {
 				if (position != 0) {
-					throw PositionOutOfBoundsException.position(position, getOrientation());
+					throw new PositionOutOfBoundsException(position, getOrientation());
 				}
 				return this.layer.size;
 			}
@@ -88,29 +92,30 @@ public class PlaceholderLayer extends DimensionallyDependentLayer {
 		private static long idCounter;
 		
 		
+		private final long id;
+		
 		private int size= DataLayer.DEFAULT_ROW_HEIGHT;
 		
 		
 		public DummyLayer() {
+			this.id= PositionId.PLACEHOLDER_CAT + idCounter++;
+			
+			init();
 		}
 		
-		
 		@Override
-		protected void initDims() {
-			final long id= PositionId.PLACEHOLDER_CAT + idCounter++;
-			for (final Orientation orientation : Orientation.values()) {
-				setDim(new Dim(this, orientation, id));
-			}
+		protected DataLayerDim<DummyLayer> createDim(final Orientation orientation) {
+			return new Dim(this, orientation, this.id);
 		}
 		
 		
 		@Override
-		public ILayer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
+		public @Nullable Layer getUnderlyingLayerByPosition(final long columnPosition, final long rowPosition) {
 			return null;
 		}
 		
 		@Override
-		public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+		public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
 			throw new UnsupportedOperationException();
 		}
 		
@@ -125,7 +130,8 @@ public class PlaceholderLayer extends DimensionallyDependentLayer {
 	 * @param verticalLayerDependency
 	 *            The layer to link the vertical dimension to, typically the column header layer
 	 */
-	public PlaceholderLayer(final ILayer horizontalLayerDependency, final ILayer verticalLayerDependency) {
+	public PlaceholderLayer(final @Nullable Layer horizontalLayerDependency,
+			final @Nullable Layer verticalLayerDependency) {
 		this(horizontalLayerDependency, verticalLayerDependency, true, new CellLayerPainter());
 	}
 	
@@ -139,16 +145,16 @@ public class PlaceholderLayer extends DimensionallyDependentLayer {
 	 * @param layerPainter
 	 *            The painter for this layer or <code>null</code> to use the painter of the base layer
 	 */
-	public PlaceholderLayer(final ILayer horizontalLayerDependency, final ILayer verticalLayerDependency,
-			final boolean useDefaultConfiguration, final ILayerPainter layerPainter) {
-		super(new DummyLayer());
+	public PlaceholderLayer(final @Nullable Layer horizontalLayerDependency,
+			final @Nullable Layer verticalLayerDependency,
+			final boolean useDefaultConfiguration, final LayerPainter layerPainter) {
+		super(new DummyLayer(),
+				layerPainter );
 		
 		setHorizontalLayerDependency((horizontalLayerDependency != null) ?
 				horizontalLayerDependency : getBaseLayer() );
 		setVerticalLayerDependency((verticalLayerDependency != null) ?
 				verticalLayerDependency : getBaseLayer() );
-		
-		this.layerPainter= layerPainter;
 	}
 	
 	
@@ -157,16 +163,16 @@ public class PlaceholderLayer extends DimensionallyDependentLayer {
 	}
 	
 	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
-		final ILayerDim hDim= getDim(HORIZONTAL);
-		final ILayerDim vDim= getDim(VERTICAL);
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+		final LayerDim hDim= getDim(HORIZONTAL);
+		final LayerDim vDim= getDim(VERTICAL);
 		final long columnId= hDim.getPositionId(columnPosition, columnPosition);
 		final long rowId= vDim.getPositionId(rowPosition, rowPosition);
 		
-		return new LayerCell(this,
-				new LayerCellDim(HORIZONTAL, columnId,
+		return new BasicLayerCell(this,
+				new BasicLayerCellDim(HORIZONTAL, columnId,
 						columnPosition, 0, hDim.getPositionCount() ),
-				new LayerCellDim(VERTICAL, rowId,
+				new BasicLayerCellDim(VERTICAL, rowId,
 						rowPosition, 0, vDim.getPositionCount() ));
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/RowHeaderLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/RowHeaderLayer.java
index 2429ad0a..65ba0c2f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/layer/RowHeaderLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/core/layers/RowHeaderLayer.java
@@ -11,20 +11,23 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.layer;
+package org.eclipse.statet.ecommons.waltable.grid.core.layers;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
 import org.eclipse.statet.ecommons.waltable.layer.config.DefaultRowHeaderLayerConfiguration;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 import org.eclipse.statet.ecommons.waltable.style.SelectionStyleLabels;
 
 
 /**
  * Layer for the row headers of the grid layer
  */
+@NonNullByDefault
 public class RowHeaderLayer extends AbstractPositionHeaderLayer {
 	
 	
@@ -38,11 +41,11 @@ public class RowHeaderLayer extends AbstractPositionHeaderLayer {
 	 * @param selectionLayer
 	 *            The selection layer required to respond to selection events
 	 */
-	public RowHeaderLayer(final ILayer baseLayer, final ILayer verticalLayerDependency, final SelectionLayer selectionLayer) {
+	public RowHeaderLayer(final Layer baseLayer, final Layer verticalLayerDependency, final SelectionLayer selectionLayer) {
 		this(baseLayer, verticalLayerDependency, selectionLayer, true);
 	}
 	
-	public RowHeaderLayer(final ILayer baseLayer, final ILayer verticalLayerDependency, final SelectionLayer selectionLayer,
+	public RowHeaderLayer(final Layer baseLayer, final Layer verticalLayerDependency, final SelectionLayer selectionLayer,
 			final boolean useDefaultConfiguration) {
 		this(baseLayer, verticalLayerDependency, selectionLayer, useDefaultConfiguration, null);
 	}
@@ -59,8 +62,9 @@ public class RowHeaderLayer extends AbstractPositionHeaderLayer {
 	 * @param layerPainter
 	 *            The painter for this layer or <code>null</code> to use the painter of the base layer
 	 */
-	public RowHeaderLayer(final ILayer baseLayer, final ILayer verticalLayerDependency,
-			final SelectionLayer selectionLayer, final boolean useDefaultConfiguration, final ILayerPainter layerPainter) {
+	public RowHeaderLayer(final Layer baseLayer, final Layer verticalLayerDependency,
+			final SelectionLayer selectionLayer, final boolean useDefaultConfiguration,
+			final LayerPainter layerPainter) {
 		super(baseLayer, VERTICAL, verticalLayerDependency,
 				selectionLayer, SelectionStyleLabels.ROW_FULLY_SELECTED_STYLE,
 				layerPainter );
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/swt/CornerGridLineCellLayerPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/swt/CornerGridLineCellLayerPainter.java
new file mode 100644
index 00000000..b8480700
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/grid/swt/CornerGridLineCellLayerPainter.java
@@ -0,0 +1,102 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.grid.swt;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
+
+import java.util.function.Function;
+
+import org.eclipse.swt.graphics.Color;
+import org.eclipse.swt.graphics.GC;
+import org.eclipse.swt.graphics.Rectangle;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.swt.painters.GridLineCellLayerPainter;
+
+
+@NonNullByDefault
+public class CornerGridLineCellLayerPainter extends GridLineCellLayerPainter {
+	
+	
+	public CornerGridLineCellLayerPainter(final Function<ConfigRegistry, Color> gridLineColorSupplier) {
+		super(gridLineColorSupplier);
+	}
+	
+	public CornerGridLineCellLayerPainter() {
+		super();
+	}
+	
+	
+	private Layer getCornerLayer(final Layer layer) {
+		return layer.getUnderlyingLayerByPosition(0, 0).getUnderlyingLayerByPosition(0, 0);
+	}
+	
+	
+	@Override
+	protected void drawHorizontalLines(final Layer natLayer, final GC gc, final Rectangle rectangle) {
+		final int startX, endX;
+		{	final LayerDim hDim= natLayer.getDim(HORIZONTAL);
+			startX= safe(rectangle.x + hDim.getPositionStart(
+					getCornerLayer(natLayer).getColumnCount() - 1 ) - 1 );
+			endX= safe(rectangle.x + Math.min(hDim.getSize() - 1, rectangle.width));
+		}
+		
+		final LayerDim dim= natLayer.getDim(VERTICAL);
+		final long lastPosition= getEndPosition(dim, rectangle.y + rectangle.height) - 1;
+		if (startX < endX) {
+			for (long position= dim.getPositionByPixel(rectangle.y); position < lastPosition; position++) {
+				final int size= dim.getPositionSize(position);
+				if (size > 0) {
+					final int y= safe(dim.getPositionStart(position) + dim.getPositionSize(position) - 1);
+					gc.drawLine(startX, y, endX, y);
+				}
+			}
+		}
+		{	final int y= safe(dim.getPositionStart(lastPosition) + dim.getPositionSize(lastPosition) - 1);
+			gc.drawLine(safe(rectangle.x), y, endX, y);
+		}
+	}
+	
+	@Override
+	protected void drawVerticalLines(final Layer natLayer, final GC gc, final Rectangle rectangle) {
+		final int startY, endY;
+		{	final LayerDim vDim= natLayer.getDim(VERTICAL);
+			startY= safe(rectangle.y + vDim.getPositionStart(
+					getCornerLayer(natLayer).getRowCount() - 1 ) - 1 );
+			endY= safe(rectangle.y + Math.min(vDim.getSize() - 1, rectangle.height));
+		}
+		
+		final LayerDim dim= natLayer.getDim(HORIZONTAL);
+		final long lastPosition= getEndPosition(dim, rectangle.x + rectangle.width) - 1;
+		if (startY < endY) {
+			for (long position= dim.getPositionByPixel(rectangle.x); position < lastPosition; position++) {
+				final int size= dim.getPositionSize(position);
+				if (size > 0) {
+					final int x= safe(dim.getPositionStart(position) + size - 1);
+					gc.drawLine(x, startY, x, endY);
+				}
+			}
+		}
+		{	final int x= safe(dim.getPositionStart(lastPosition) + dim.getPositionSize(lastPosition) - 1);
+			gc.drawLine(x, safe(rectangle.y), x, endY);
+		}
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/StructuralRefreshCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/refresh/core/StructuralRefreshCommand.java
index f8713984..a7f2002b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/StructuralRefreshCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/refresh/core/StructuralRefreshCommand.java
@@ -11,30 +11,22 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.refresh.core;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralRefreshEvent;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.GeneralStructuralChangeEvent;
 
 
 /**
- * Command that triggers a {@link StructuralRefreshEvent}.
+ * Command that triggers a {@link GeneralStructuralChangeEvent}.
  * To support refreshing of every layer in a NatTable the
  * {@link StructuralRefreshCommandHandler} should be registered 
  * against the DataLayer.
  */
-public class StructuralRefreshCommand implements ILayerCommand {
-
-	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
-		// no need for a check as the command simply triggers the firing of a StructuralRefreshEvent
-		return true;
-	}
-
-	@Override
-	public ILayerCommand cloneCommand() {
-		// as the command doesn't have a state, the clone is simply a new instance
-		return new StructuralRefreshCommand();
-	}
-
+@NonNullByDefault
+public class StructuralRefreshCommand extends AbstractContextFreeCommand {
+	
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/StructuralRefreshCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/refresh/core/StructuralRefreshCommandHandler.java
index 72c52ff1..e7d846db 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/StructuralRefreshCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/refresh/core/StructuralRefreshCommandHandler.java
@@ -11,15 +11,18 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.refresh.core;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralRefreshEvent;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.GeneralStructuralChangeEvent;
 
 
 /**
  * Command handler for handling {@link StructuralRefreshCommand}s.
- * Simply fires a {@link StructuralRefreshEvent}.
+ * Simply fires a {@link GeneralStructuralChangeEvent}.
  * 
  * Needed to be able to refresh all layers by simply calling a command on the NatTable
  * instance itself (Remember that events are fired bottom up the layer stack while commands
@@ -29,17 +32,27 @@ import org.eclipse.statet.ecommons.waltable.layer.event.StructuralRefreshEvent;
  * instance, the {@link StructuralRefreshCommandHandler} should be registered against
  * the DataLayer.
  */
-public class StructuralRefreshCommandHandler implements ILayerCommandHandler<StructuralRefreshCommand> {
-
+@NonNullByDefault
+public class StructuralRefreshCommandHandler implements LayerCommandHandler<StructuralRefreshCommand> {
+	
+	
+	private final Layer layer;
+	
+	
+	public StructuralRefreshCommandHandler(final Layer layer) {
+		this.layer= layer;
+	}
+	
+	
 	@Override
 	public Class<StructuralRefreshCommand> getCommandClass() {
 		return StructuralRefreshCommand.class;
 	}
-
+	
 	@Override
-	public boolean doCommand(final ILayer targetLayer, final StructuralRefreshCommand command) {
-		targetLayer.fireLayerEvent(new StructuralRefreshEvent(targetLayer));
+	public boolean executeCommand(final StructuralRefreshCommand command) {
+		this.layer.fireLayerEvent(new GeneralStructuralChangeEvent(this.layer));
 		return false;
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/VisualRefreshCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/refresh/core/VisualRefreshCommand.java
index 2aeab226..66d2cd99 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/VisualRefreshCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/refresh/core/VisualRefreshCommand.java
@@ -11,30 +11,22 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.refresh.core;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.VisualRefreshEvent;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.GeneralVisualChangeEvent;
 
 
 /**
- * Command that triggers a {@link VisualRefreshEvent}.
+ * Command that triggers a {@link GeneralVisualChangeEvent}.
  * To support refreshing of every layer in a NatTable the
  * {@link VisualRefreshCommandHandler} should be registered 
  * against the DataLayer.
  */
-public class VisualRefreshCommand implements ILayerCommand {
-
-	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
-		// no need for a check as the command simply triggers the firing of a VisualRefreshEvent
-		return true;
-	}
-
-	@Override
-	public ILayerCommand cloneCommand() {
-		// as the command doesn't have a state, the clone is simply a new instance
-		return new VisualRefreshCommand();
-	}
-
+@NonNullByDefault
+public class VisualRefreshCommand extends AbstractContextFreeCommand {
+	
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/VisualRefreshCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/refresh/core/VisualRefreshCommandHandler.java
index 402129a9..b47dc74b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/command/VisualRefreshCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/refresh/core/VisualRefreshCommandHandler.java
@@ -11,15 +11,18 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.command;
+package org.eclipse.statet.ecommons.waltable.refresh.core;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.VisualRefreshEvent;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.GeneralVisualChangeEvent;
 
 
 /**
  * Command handler for handling {@link VisualRefreshCommand}s.
- * Simply fires a {@link VisualRefreshEvent}.
+ * Simply fires a {@link GeneralVisualChangeEvent}.
  * 
  * Needed to be able to refresh all layers by simply calling a command on the NatTable
  * instance itself (Remember that events are fired bottom up the layer stack while commands
@@ -29,16 +32,26 @@ import org.eclipse.statet.ecommons.waltable.layer.event.VisualRefreshEvent;
  * instance, the {@link VisualRefreshCommandHandler} should be registered against
  * the DataLayer.
  */
-public class VisualRefreshCommandHandler implements ILayerCommandHandler<VisualRefreshCommand> {
-
+@NonNullByDefault
+public class VisualRefreshCommandHandler implements LayerCommandHandler<VisualRefreshCommand> {
+	
+	
+	private final Layer layer;
+	
+	
+	public VisualRefreshCommandHandler(final Layer layer) {
+		this.layer= layer;
+	}
+	
+	
 	@Override
 	public Class<VisualRefreshCommand> getCommandClass() {
 		return VisualRefreshCommand.class;
 	}
-
+	
 	@Override
-	public boolean doCommand(final ILayer targetLayer, final VisualRefreshCommand command) {
-		targetLayer.fireLayerEvent(new VisualRefreshEvent(targetLayer));
+	public boolean executeCommand(final VisualRefreshCommand command) {
+		this.layer.fireLayerEvent(new GeneralVisualChangeEvent(this.layer));
 		return true;
 	}
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/ColumnResizeEventMatcher.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ColumnResizeEventMatcher.java
index b66b5355..db7601a9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/ColumnResizeEventMatcher.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ColumnResizeEventMatcher.java
@@ -13,16 +13,16 @@
 
 package org.eclipse.statet.ecommons.waltable.resize;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.MouseEventMatcher;
 import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeDetectUtil;
 
@@ -31,11 +31,11 @@ public class ColumnResizeEventMatcher extends MouseEventMatcher {
 	
 	
 	public ColumnResizeEventMatcher(final int button, final boolean rowColumn) {
-		super(SWT.NONE, GridRegion.COLUMN_HEADER, (rowColumn) ? GridRegion.CORNER : null, button);
+		super(SWT.NONE, GridLabels.COLUMN_HEADER, (rowColumn) ? GridLabels.CORNER : null, button);
 	}
 	
 	public ColumnResizeEventMatcher(final int button) {
-		this(SWT.NONE, GridRegion.COLUMN_HEADER, button);
+		this(SWT.NONE, GridLabels.COLUMN_HEADER, button);
 	}
 	
 	public ColumnResizeEventMatcher(final int stateMask, final String eventRegion, final int button) {
@@ -48,7 +48,7 @@ public class ColumnResizeEventMatcher extends MouseEventMatcher {
 		return super.matches(natTable, event, regionLabels) && isResizable(natTable, event);
 	}
 	
-	private boolean isResizable(final ILayer natLayer, final MouseEvent event) {
+	private boolean isResizable(final Layer natLayer, final MouseEvent event) {
 		final long columnPosition= CellEdgeDetectUtil.getPositionToResize(natLayer,
 				new LPoint(event.x, event.y), HORIZONTAL );
 		
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/PositionResizeDragMode.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/PositionResizeDragMode.java
index 8efdc468..2d8fbcb3 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/PositionResizeDragMode.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/PositionResizeDragMode.java
@@ -13,23 +13,23 @@
 
 package org.eclipse.statet.ecommons.waltable.resize;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.check;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import org.eclipse.swt.events.MouseEvent;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.NatTableDim;
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.painter.IOverlayPainter;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
+import org.eclipse.statet.ecommons.waltable.NatTableLayerDim;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.top.OverlayPainter;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
+import org.eclipse.statet.ecommons.waltable.resize.core.DimPositionResizeCommand;
 import org.eclipse.statet.ecommons.waltable.ui.action.IDragMode;
 import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeDetectUtil;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
@@ -46,7 +46,7 @@ public class PositionResizeDragMode implements IDragMode {
 	private static final int RESIZE_OVERLAY_SIZE= 2;
 	
 	
-	private static void addPositions(final long pixel, final ILayerDim dim, final LRangeList positions) {
+	private static void addPositions(final long pixel, final LayerDim dim, final LRangeList positions) {
 		final long startPixel= Math.max(pixel - RESIZE_OVERLAY_SIZE / 2, 0);
 		final long endPixel= Math.min(pixel + RESIZE_OVERLAY_SIZE / 2, dim.getSize() - 1);
 		if (startPixel < endPixel) {
@@ -55,25 +55,25 @@ public class PositionResizeDragMode implements IDragMode {
 	}
 	
 	
-	private class ColumnResizeOverlayPainter implements IOverlayPainter {
+	private class ColumnResizeOverlayPainter implements OverlayPainter {
 		
 		@Override
-		public void paintOverlay(final GC gc, final ILayer layer) {
+		public void paintOverlay(final GC gc, final Layer layer) {
 			final Color originalBackgroundColor= gc.getBackground();
 			gc.setBackground(GUIHelper.COLOR_DARK_GRAY);
-			gc.fillRectangle(PositionResizeDragMode.this.currentPixel - (RESIZE_OVERLAY_SIZE / 2), 0, RESIZE_OVERLAY_SIZE, check(layer.getHeight()));
+			gc.fillRectangle(PositionResizeDragMode.this.currentPixel - (RESIZE_OVERLAY_SIZE / 2), 0, RESIZE_OVERLAY_SIZE, SwtUtils.toSWT(layer.getHeight()));
 			gc.setBackground(originalBackgroundColor);
 		}
 		
 	}
 	
-	private class RowResizeOverlayPainter implements IOverlayPainter {
+	private class RowResizeOverlayPainter implements OverlayPainter {
 		
 		@Override
-		public void paintOverlay(final GC gc, final ILayer layer) {
+		public void paintOverlay(final GC gc, final Layer layer) {
 			final Color originalBackgroundColor= gc.getBackground();
 			gc.setBackground(GUIHelper.COLOR_DARK_GRAY);
-			gc.fillRectangle(0, PositionResizeDragMode.this.currentPixel - (RESIZE_OVERLAY_SIZE / 2), check(layer.getWidth()), RESIZE_OVERLAY_SIZE);
+			gc.fillRectangle(0, PositionResizeDragMode.this.currentPixel - (RESIZE_OVERLAY_SIZE / 2), SwtUtils.toSWT(layer.getWidth()), RESIZE_OVERLAY_SIZE);
 			gc.setBackground(originalBackgroundColor);
 		}
 	}
@@ -90,7 +90,7 @@ public class PositionResizeDragMode implements IDragMode {
 	private int currentPixel;
 	private int lastPixel= -1;
 	
-	private final IOverlayPainter overlayPainter;
+	private final OverlayPainter overlayPainter;
 	
 	
 	public PositionResizeDragMode(final Orientation orientation) {
@@ -114,11 +114,11 @@ public class PositionResizeDragMode implements IDragMode {
 		this.positionToResize= CellEdgeDetectUtil.getPositionToResize(natTable,
 				new LPoint(event.x, event.y), this.orientation );
 		if (this.positionToResize >= 0) {
-			final ILayerDim dim= natTable.getDim(this.orientation);
+			final LayerDim layerDim= natTable.getDim(this.orientation);
 			
-			this.positionStart= check(dim.getPositionStart(this.positionToResize));
-			this.positionSize= dim.getPositionSize(this.positionToResize);
-			this.startPixel= SWTUtil.get(event, this.orientation);
+			this.positionStart= SwtUtils.toSWT(layerDim.getPositionStart(this.positionToResize));
+			this.positionSize= layerDim.getPositionSize(this.positionToResize);
+			this.startPixel= SwtUtils.getPixel(event, this.orientation);
 			
 			natTable.addOverlayPainter(this.overlayPainter);
 		}
@@ -126,10 +126,10 @@ public class PositionResizeDragMode implements IDragMode {
 	
 	@Override
 	public void mouseMove(final NatTable natTable, final MouseEvent event) {
-		final NatTableDim dim= natTable.getDim(this.orientation);
+		final NatTableLayerDim layerDim= natTable.getDim(this.orientation);
 		
-		final int pixel= SWTUtil.get(event, this.orientation);
-		if (pixel > dim.getSize()) {
+		final int pixel= SwtUtils.getPixel(event, this.orientation);
+		if (pixel > layerDim.getSize()) {
 			return;
 		}
 		
@@ -141,12 +141,12 @@ public class PositionResizeDragMode implements IDragMode {
 			
 			final LRangeList positionsToRepaint= new LRangeList();
 			
-			addPositions(this.currentPixel, dim, positionsToRepaint);
+			addPositions(this.currentPixel, layerDim, positionsToRepaint);
 			if (this.lastPixel >= 0) {
-				addPositions(this.lastPixel, dim, positionsToRepaint);
+				addPositions(this.lastPixel, layerDim, positionsToRepaint);
 			}
 			for (final LRange positions : positionsToRepaint) {
-				dim.repaintPositions(positions);
+				layerDim.repaintPositions(positions);
 			}
 			
 			this.lastPixel= this.currentPixel;
@@ -155,21 +155,22 @@ public class PositionResizeDragMode implements IDragMode {
 	
 	@Override
 	public void mouseUp(final NatTable natTable, final MouseEvent event) {
-		final NatTableDim dim= natTable.getDim(this.orientation);
+		final NatTableLayerDim layerDim= natTable.getDim(this.orientation);
 		
 		natTable.removeOverlayPainter(this.overlayPainter);
 		
-		updatePositionSize(dim, SWTUtil.get(event, this.orientation));
+		updatePositionSize(layerDim, SwtUtils.getPixel(event, this.orientation));
 	}
 	
-	private void updatePositionSize(final ILayerDim dim, final int pixel) {
+	private void updatePositionSize(final LayerDim layerDim, final int pixel) {
 		final int dragSize= pixel - this.startPixel;
 		int newSize= this.positionSize + dragSize;
 		if (newSize < getMinPositionSize()) {
 			newSize= getMinPositionSize();
 		}
 		
-		dim.getLayer().doCommand(new DimPositionResizeCommand(dim, this.positionToResize, newSize));
+		layerDim.getLayer().doCommand(
+				new DimPositionResizeCommand(layerDim, this.positionToResize, newSize) );
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/RowResizeEventMatcher.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/RowResizeEventMatcher.java
index 76d54d30..b0db6ba9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/RowResizeEventMatcher.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/RowResizeEventMatcher.java
@@ -13,16 +13,16 @@
 
 package org.eclipse.statet.ecommons.waltable.resize;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.MouseEventMatcher;
 import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeDetectUtil;
 
@@ -31,7 +31,7 @@ public class RowResizeEventMatcher extends MouseEventMatcher {
 	
 	
 	public RowResizeEventMatcher(final int button) {
-		this(SWT.NONE, GridRegion.ROW_HEADER, button);
+		this(SWT.NONE, GridLabels.ROW_HEADER, button);
 	}
 	
 	public RowResizeEventMatcher(final int stateMask, final String eventRegion, final int button) {
@@ -44,7 +44,7 @@ public class RowResizeEventMatcher extends MouseEventMatcher {
 		return super.matches(natTable, event, regionLabels) && isResizable(natTable, event);
 	}
 	
-	private boolean isResizable(final ILayer natLayer, final MouseEvent event) {
+	private boolean isResizable(final Layer natLayer, final MouseEvent event) {
 		final long rowPosition= CellEdgeDetectUtil.getPositionToResize(natLayer,
 				new LPoint(event.x, event.y), VERTICAL );
 		
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/AutoResizePositionsCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/AutoResizePositionsCommand.java
index 2e0cda22..c4355c62 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/AutoResizePositionsCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/AutoResizePositionsCommand.java
@@ -11,12 +11,14 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize;
+package org.eclipse.statet.ecommons.waltable.resize.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionsCommand;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionsCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
 
 
 /**
@@ -27,10 +29,11 @@ import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
  * Note: The {@link InitializeAutoResizeCommand} has to be fired first
  * when autoresizing columns.
  */
+@NonNullByDefault
 public class AutoResizePositionsCommand extends AbstractDimPositionsCommand {
 	
 	
-	public AutoResizePositionsCommand(final ILayerDim layerDim, final LRangeList columnPositions) {
+	public AutoResizePositionsCommand(final LayerDim layerDim, final LRangeList columnPositions) {
 		super(layerDim, columnPositions);
 	}
 	
@@ -39,7 +42,7 @@ public class AutoResizePositionsCommand extends AbstractDimPositionsCommand {
 	}
 	
 	@Override
-	public ILayerCommand cloneCommand() {
+	public LayerCommand cloneCommand() {
 		return new AutoResizePositionsCommand(this);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/DimPositionResizeCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/DimPositionResizeCommand.java
index 8f76955f..a4c72b78 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/DimPositionResizeCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/DimPositionResizeCommand.java
@@ -11,22 +11,25 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize;
+package org.eclipse.statet.ecommons.waltable.resize.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
 
 
 /**
  * Event indicating that a column has been resized.
  */
+@NonNullByDefault
 public class DimPositionResizeCommand extends AbstractDimPositionCommand {
 	
 	
 	private final int newSize;
 	
 	
-	public DimPositionResizeCommand(final ILayerDim layerDim, final long position, final int newSize) {
+	public DimPositionResizeCommand(final LayerDim layerDim, final long position, final int newSize) {
 		super(layerDim, position);
 		
 		this.newSize= newSize;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/DimResizeEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/DimResizeEvent.java
new file mode 100644
index 00000000..cf436301
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/DimResizeEvent.java
@@ -0,0 +1,67 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.resize.core;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.DimPositionsStructuralChangeEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralDiff;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralDiff.DiffType;
+
+
+@NonNullByDefault
+public class DimResizeEvent extends DimPositionsStructuralChangeEvent {
+	
+	
+	public DimResizeEvent(final LayerDim layerDim, final LRange positions) {
+		super(layerDim, ImCollections.newList(positions));
+	}
+	
+	public DimResizeEvent(final LayerDim layerDim, final List<LRange> positions) {
+		super(layerDim, positions);
+	}
+	
+	
+	@Override
+	protected @Nullable DimResizeEvent toLayer(final LayerDim targetLayerDim,
+			final List<LRange> positions) {
+		return new DimResizeEvent(targetLayerDim, positions);
+	}
+	
+	
+	@Override
+	public @Nullable List<StructuralDiff> getDiffs(final Orientation orientation) {
+		if (orientation == getOrientation()) {
+			final var diffs= new ArrayList<StructuralDiff>();
+			
+			for (final LRange lRange : getPositionRanges()) {
+				diffs.add(new StructuralDiff(DiffType.CHANGE, lRange, lRange));
+			}
+			
+			return diffs;
+		}
+		else {
+			return null;
+		}
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/InitializeAutoResizeCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/InitializeAutoResizeCommand.java
index 9620130c..3618f0fc 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/InitializeAutoResizeCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/InitializeAutoResizeCommand.java
@@ -11,13 +11,15 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize;
+package org.eclipse.statet.ecommons.waltable.resize.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionCommand;
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.grid.layer.GridLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionCommand;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLayer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 
 
 /**
@@ -25,10 +27,11 @@ import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
  * columns from the {@link SelectionLayer} and fires the
  * {@link AutoResizePositionsCommand} on the {@link GridLayer}
  */
+@NonNullByDefault
 public class InitializeAutoResizeCommand extends AbstractDimPositionCommand {
 	
 	
-	public InitializeAutoResizeCommand(final ILayerDim layer, final long position) {
+	public InitializeAutoResizeCommand(final LayerDim layer, final long position) {
 		super(layer, position);
 	}
 	
@@ -37,7 +40,7 @@ public class InitializeAutoResizeCommand extends AbstractDimPositionCommand {
 	}
 	
 	@Override
-	public ILayerCommand cloneCommand() {
+	public LayerCommand cloneCommand() {
 		return new InitializeAutoResizeCommand(this);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/InitializeAutoResizeCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/InitializeAutoResizeCommandHandler.java
index 4b707b42..7d219d29 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/InitializeAutoResizeCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/InitializeAutoResizeCommandHandler.java
@@ -11,15 +11,18 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize;
+package org.eclipse.statet.ecommons.waltable.resize.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.LayerUtil;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerUtils;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 
+
+@NonNullByDefault
 public class InitializeAutoResizeCommandHandler extends AbstractLayerCommandHandler<InitializeAutoResizeCommand> {
 	
 	
@@ -38,13 +41,13 @@ public class InitializeAutoResizeCommandHandler extends AbstractLayerCommandHand
 	
 	@Override
 	protected boolean doCommand(final InitializeAutoResizeCommand initCommand) {
-		final ILayerDim layerDim= initCommand.getDim();
+		final LayerDim layerDim= initCommand.getDim();
 		final long position= initCommand.getPosition();
 		final LRangeList positions;
 		
-		final long selectionPosition= LayerUtil.convertPosition(layerDim,
+		final long selectionPosition= LayerUtils.convertPosition(layerDim,
 				position, position, this.selectionLayer.getDim(layerDim.getOrientation()) );
-		if (selectionPosition != ILayerDim.POSITION_NA
+		if (selectionPosition != LayerDim.POSITION_NA
 				&& this.selectionLayer.isPositionFullySelected(layerDim.getOrientation(), position) ) {
 			positions= this.selectionLayer.getFullySelectedPositions(layerDim.getOrientation());
 			
@@ -57,7 +60,6 @@ public class InitializeAutoResizeCommandHandler extends AbstractLayerCommandHand
 			layerDim.getLayer().doCommand(new AutoResizePositionsCommand(layerDim, positions));
 		}
 		
-		// Fire command carrying the selected columns
 		return true;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/MultiColumnResizeCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/MultiColumnResizeCommand.java
index aa7454a3..66f85845 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/MultiColumnResizeCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/MultiColumnResizeCommand.java
@@ -11,24 +11,28 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize;
+package org.eclipse.statet.ecommons.waltable.resize.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionsCommand;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
 import org.eclipse.statet.ecommons.waltable.command.LayerCommandUtil;
 import org.eclipse.statet.ecommons.waltable.coordinate.ColumnPositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionsCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
+@NonNullByDefault
 public class MultiColumnResizeCommand extends AbstractDimPositionsCommand {
-
+	
+	
 	private int commonColumnWidth= -1;
 	protected Map<ColumnPositionCoordinate, Integer> colPositionToWidth= new HashMap<>();
 	
@@ -36,7 +40,7 @@ public class MultiColumnResizeCommand extends AbstractDimPositionsCommand {
 	/**
 	 * All columns are being resized to the same width e.g. during a drag resize
 	 */
-	public MultiColumnResizeCommand(final ILayer layer, final Collection<LRange> columnPositions, final int commonColumnWidth) {
+	public MultiColumnResizeCommand(final Layer layer, final Collection<LRange> columnPositions, final int commonColumnWidth) {
 		super(layer.getDim(HORIZONTAL), columnPositions);
 		this.commonColumnWidth= commonColumnWidth;
 	}
@@ -44,7 +48,7 @@ public class MultiColumnResizeCommand extends AbstractDimPositionsCommand {
 	/**
 	 * Each column is being resized to a different size e.g. during auto resize
 	 */
-	public MultiColumnResizeCommand(final ILayer layer, final long[] columnPositions, final int[] columnWidths) {
+	public MultiColumnResizeCommand(final Layer layer, final long[] columnPositions, final int[] columnWidths) {
 		super(layer.getDim(HORIZONTAL), new LRangeList(columnPositions));
 		for (int i= 0; i < columnPositions.length; i++) {
 			this.colPositionToWidth.put(new ColumnPositionCoordinate(layer, columnPositions[i]), Integer.valueOf(columnWidths[i]));
@@ -77,7 +81,7 @@ public class MultiColumnResizeCommand extends AbstractDimPositionsCommand {
 	}
 	
 	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
+	public boolean convertToTargetLayer(final Layer targetLayer) {
 		if (super.convertToTargetLayer(targetLayer)) {
 			// Ensure that the width associated with the column is now associated with the converted 
 			// column position.
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/MultiColumnResizeCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/MultiColumnResizeCommandHandler.java
index 9ca1100b..b2cbe3e9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/MultiColumnResizeCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/MultiColumnResizeCommandHandler.java
@@ -11,14 +11,17 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize;
+package org.eclipse.statet.ecommons.waltable.resize.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.ILValueIterator;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList.ValueIterator;
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
+import org.eclipse.statet.jcommons.collections.LongIterator;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList.ValueIterator;
+import org.eclipse.statet.ecommons.waltable.data.core.DataLayer;
 
+
+@NonNullByDefault
 public class MultiColumnResizeCommandHandler extends AbstractLayerCommandHandler<MultiColumnResizeCommand> {
 	
 	
@@ -36,7 +39,7 @@ public class MultiColumnResizeCommandHandler extends AbstractLayerCommandHandler
 	
 	@Override
 	protected boolean doCommand(final MultiColumnResizeCommand command) {
-		for (final ILValueIterator columnIter= new ValueIterator(command.getPositions()); columnIter.hasNext(); ) {
+		for (final LongIterator columnIter= new ValueIterator(command.getPositions()); columnIter.hasNext(); ) {
 			final long columnPosition= columnIter.nextValue();
 			this.dataLayer.setColumnWidthByPosition(columnPosition, command.getColumnWidth(columnPosition));
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/MultiRowResizeCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/MultiRowResizeCommand.java
index 04debfdf..67714092 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/MultiRowResizeCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/MultiRowResizeCommand.java
@@ -11,20 +11,20 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize;
+package org.eclipse.statet.ecommons.waltable.resize.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionsCommand;
 import org.eclipse.statet.ecommons.waltable.command.LayerCommandUtil;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
 import org.eclipse.statet.ecommons.waltable.coordinate.RowPositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionsCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 public class MultiRowResizeCommand extends AbstractDimPositionsCommand {
@@ -36,7 +36,7 @@ public class MultiRowResizeCommand extends AbstractDimPositionsCommand {
 	/**
 	 * All rows are being resized to the same height e.g. during a drag resize
 	 */
-	public MultiRowResizeCommand(final ILayer layer, final Collection<LRange> rowPositions, final int commonRowHeight) {
+	public MultiRowResizeCommand(final Layer layer, final Collection<LRange> rowPositions, final int commonRowHeight) {
 		super(layer.getDim(VERTICAL), rowPositions);
 		this.commonRowHeight= commonRowHeight;
 	}
@@ -44,7 +44,7 @@ public class MultiRowResizeCommand extends AbstractDimPositionsCommand {
 	/**
 	 * Each row is being resized to a different size e.g. during auto resize
 	 */
-	public MultiRowResizeCommand(final ILayer layer, final long[] rowPositions, final int[] rowHeights) {
+	public MultiRowResizeCommand(final Layer layer, final long[] rowPositions, final int[] rowHeights) {
 		super(layer.getDim(VERTICAL), new LRangeList(rowPositions));
 		for (int i= 0; i < rowPositions.length; i++) {
 			this.rowPositionToHeight.put(new RowPositionCoordinate(layer, rowPositions[i]), Integer.valueOf(rowHeights[i]));
@@ -77,7 +77,7 @@ public class MultiRowResizeCommand extends AbstractDimPositionsCommand {
 	}
 	
 	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
+	public boolean convertToTargetLayer(final Layer targetLayer) {
 		if (super.convertToTargetLayer(targetLayer)) {
 			// Ensure that the height associated with the row is now associated with the converted 
 			// row position.
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/MultiRowResizeCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/MultiRowResizeCommandHandler.java
index dcdf65b4..1d911b7c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/MultiRowResizeCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/MultiRowResizeCommandHandler.java
@@ -11,18 +11,23 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize;
+package org.eclipse.statet.ecommons.waltable.resize.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.ILValueIterator;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList.ValueIterator;
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
+import org.eclipse.statet.jcommons.collections.LongIterator;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList.ValueIterator;
+import org.eclipse.statet.ecommons.waltable.data.core.DataLayer;
 
-public class MultiRowResizeCommandHandler extends AbstractLayerCommandHandler<MultiRowResizeCommand> {
 
+@NonNullByDefault
+public class MultiRowResizeCommandHandler extends AbstractLayerCommandHandler<MultiRowResizeCommand> {
+	
+	
 	private final DataLayer dataLayer;
-
+	
+	
 	public MultiRowResizeCommandHandler(final DataLayer dataLayer) {
 		this.dataLayer= dataLayer;
 	}
@@ -31,14 +36,14 @@ public class MultiRowResizeCommandHandler extends AbstractLayerCommandHandler<Mu
 	public Class<MultiRowResizeCommand> getCommandClass() {
 		return MultiRowResizeCommand.class;
 	}
-
+	
 	@Override
 	protected boolean doCommand(final MultiRowResizeCommand command) {
-		for (final ILValueIterator rowIter= new ValueIterator(command.getPositions()); rowIter.hasNext(); ) {
+		for (final LongIterator rowIter= new ValueIterator(command.getPositions()); rowIter.hasNext(); ) {
 			final long rowPosition= rowIter.nextValue();
 			this.dataLayer.setRowHeightByPosition(rowPosition, command.getRowHeight(rowPosition));
 		}
 		return true;
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/PositionResizeCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/PositionResizeCommandHandler.java
index a3eb5e42..6e39979a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/PositionResizeCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/core/PositionResizeCommandHandler.java
@@ -11,14 +11,17 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize;
+package org.eclipse.statet.ecommons.waltable.resize.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.layer.DataLayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.data.core.DataLayer;
 
+
+@NonNullByDefault
 public class PositionResizeCommandHandler extends AbstractLayerCommandHandler<DimPositionResizeCommand> {
 	
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/action/AutoResizeColumnAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/AutoResizeColumnAction.java
index 07770dda..6746c674 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/action/AutoResizeColumnAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/AutoResizeColumnAction.java
@@ -11,15 +11,15 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize.action;
+package org.eclipse.statet.ecommons.waltable.resize.ui.action;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.resize.InitializeAutoResizeCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.resize.core.InitializeAutoResizeCommand;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeDetectUtil;
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/action/AutoResizeRowAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/AutoResizeRowAction.java
index 607572a5..dc1f3459 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/action/AutoResizeRowAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/AutoResizeRowAction.java
@@ -11,15 +11,15 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize.action;
+package org.eclipse.statet.ecommons.waltable.resize.ui.action;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.resize.InitializeAutoResizeCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.resize.core.InitializeAutoResizeCommand;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeDetectUtil;
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/action/ColumnResizeCursorAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/ColumnResizeCursorAction.java
index 4b72a6b4..65445f6f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/action/ColumnResizeCursorAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/ColumnResizeCursorAction.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize.action;
+package org.eclipse.statet.ecommons.waltable.resize.ui.action;
 
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.DisposeEvent;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/config/DefaultColumnResizeBindings.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/DefaultColumnResizeBindings.java
index ef67db7a..c6d04d2a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/config/DefaultColumnResizeBindings.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/DefaultColumnResizeBindings.java
@@ -11,15 +11,13 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize.config;
+package org.eclipse.statet.ecommons.waltable.resize.ui.action;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractUiBindingConfiguration;
 import org.eclipse.statet.ecommons.waltable.resize.ColumnResizeEventMatcher;
 import org.eclipse.statet.ecommons.waltable.resize.PositionResizeDragMode;
-import org.eclipse.statet.ecommons.waltable.resize.action.AutoResizeColumnAction;
-import org.eclipse.statet.ecommons.waltable.resize.action.ColumnResizeCursorAction;
 import org.eclipse.statet.ecommons.waltable.ui.action.ClearCursorAction;
 import org.eclipse.statet.ecommons.waltable.ui.action.NoOpMouseAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/config/DefaultRowResizeBindings.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/DefaultRowResizeBindings.java
index 8fe8a9d6..f3b7591b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/config/DefaultRowResizeBindings.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/DefaultRowResizeBindings.java
@@ -11,15 +11,13 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize.config;
+package org.eclipse.statet.ecommons.waltable.resize.ui.action;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractUiBindingConfiguration;
 import org.eclipse.statet.ecommons.waltable.resize.PositionResizeDragMode;
 import org.eclipse.statet.ecommons.waltable.resize.RowResizeEventMatcher;
-import org.eclipse.statet.ecommons.waltable.resize.action.AutoResizeRowAction;
-import org.eclipse.statet.ecommons.waltable.resize.action.RowResizeCursorAction;
 import org.eclipse.statet.ecommons.waltable.ui.action.ClearCursorAction;
 import org.eclipse.statet.ecommons.waltable.ui.action.NoOpMouseAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/action/RowResizeCursorAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/RowResizeCursorAction.java
index a3bab5b8..5ff6a34a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/resize/action/RowResizeCursorAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/resize/ui/action/RowResizeCursorAction.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.resize.action;
+package org.eclipse.statet.ecommons.waltable.resize.ui.action;
 
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.DisposeEvent;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/DefaultMoveSelectionConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/DefaultMoveSelectionConfiguration.java
index bade097d..cf1ebef6 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/DefaultMoveSelectionConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/DefaultMoveSelectionConfiguration.java
@@ -14,7 +14,7 @@
 package org.eclipse.statet.ecommons.waltable.selection.config;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractLayerConfiguration;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionBindings.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionBindings.java
index 46a28c14..66e15358 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionBindings.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionBindings.java
@@ -16,10 +16,10 @@ package org.eclipse.statet.ecommons.waltable.selection.config;
 import org.eclipse.swt.SWT;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractUiBindingConfiguration;
-import org.eclipse.statet.ecommons.waltable.copy.action.CopyDataAction;
-import org.eclipse.statet.ecommons.waltable.selection.action.CellSelectionDragMode;
-import org.eclipse.statet.ecommons.waltable.selection.action.SelectAllAction;
-import org.eclipse.statet.ecommons.waltable.selection.action.SelectCellAction;
+import org.eclipse.statet.ecommons.waltable.copy.ui.action.CopyDataAction;
+import org.eclipse.statet.ecommons.waltable.selection.ui.action.CellSelectionDragMode;
+import org.eclipse.statet.ecommons.waltable.selection.ui.action.SelectAllAction;
+import org.eclipse.statet.ecommons.waltable.selection.ui.action.SelectCellAction;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.KeyEventMatcher;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionLayerConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionLayerConfiguration.java
index d3eb9121..30381b33 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionLayerConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionLayerConfiguration.java
@@ -14,7 +14,7 @@
 package org.eclipse.statet.ecommons.waltable.selection.config;
 
 import org.eclipse.statet.ecommons.waltable.config.AggregateConfiguration;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 import org.eclipse.statet.ecommons.waltable.tickupdate.config.DefaultTickUpdateConfiguration;
 
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionStyleConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionStyleConfiguration.java
new file mode 100644
index 00000000..43cc6297
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/DefaultSelectionStyleConfiguration.java
@@ -0,0 +1,126 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.selection.config;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.graphics.Color;
+import org.eclipse.swt.graphics.Font;
+import org.eclipse.swt.graphics.FontData;
+
+import org.eclipse.statet.ecommons.waltable.config.AbstractRegistryConfiguration;
+import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.style.BasicStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle.LineStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
+import org.eclipse.statet.ecommons.waltable.style.SelectionStyleLabels;
+import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
+
+
+/**
+ * Sets up rendering style used for selected areas and the selection anchor.
+ */
+public class DefaultSelectionStyleConfiguration extends AbstractRegistryConfiguration {
+	
+	// Selection style
+	public Font selectionFont= GUIHelper.getFont(new FontData("Verdana", 8, SWT.BOLD | SWT.ITALIC)); //$NON-NLS-1$
+	public Color selectionBgColor= GUIHelper.COLOR_TITLE_INACTIVE_BACKGROUND;
+	public Color selectionFgColor= GUIHelper.COLOR_BLACK;
+	
+	// Anchor style
+	public Color anchorBorderColor= GUIHelper.COLOR_DARK_GRAY;
+	public BorderStyle anchorBorderStyle= new BorderStyle(1, this.anchorBorderColor, LineStyle.SOLID);
+	public Color anchorBgColor= GUIHelper.COLOR_GRAY;
+	public Color anchorFgColor= GUIHelper.COLOR_WHITE;
+	
+	// Selected headers style
+	public Color selectedHeaderBgColor= GUIHelper.COLOR_GRAY;
+	public Color selectedHeaderFgColor= GUIHelper.COLOR_WHITE;
+	public Font selectedHeaderFont= GUIHelper.getFont(new FontData("Verdana", 10, SWT.BOLD)); //$NON-NLS-1$
+	public BorderStyle selectedHeaderBorderStyle= new BorderStyle(-1, this.selectedHeaderFgColor, LineStyle.SOLID);
+	
+	// Anchor grid line style
+	public Color anchorGridBorderColor= GUIHelper.COLOR_BLACK;
+	public BorderStyle anchorGridBorderStyle= new BorderStyle(1, this.anchorGridBorderColor, LineStyle.DOTTED);
+	
+	
+	@Override
+	public void configureRegistry(final ConfigRegistry configRegistry) {
+		configureSelectionStyle(configRegistry);
+		configureSelectionAnchorStyle(configRegistry);
+		configureSelectionAnchorGridLineStyle(configRegistry);
+		configureHeaderHasSelectionStyle(configRegistry);
+		configureHeaderFullySelectedStyle(configRegistry);
+	}
+	
+	protected void configureSelectionStyle(final ConfigRegistry configRegistry) {
+		final BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.FONT, this.selectionFont);
+		cellStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR, this.selectionBgColor);
+		cellStyle.setAttributeValue(CellStyling.FOREGROUND_COLOR, this.selectionFgColor);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
+				DisplayMode.SELECTED );
+	}
+	
+	protected void configureSelectionAnchorStyle(final ConfigRegistry configRegistry) {
+		// Selection anchor style for normal display mode
+		BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.BORDER_STYLE, this.anchorBorderStyle);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
+				DisplayMode.NORMAL, SelectionStyleLabels.SELECTION_ANCHOR_STYLE );
+		
+		// Selection anchor style for select display mode
+		cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR, this.anchorBgColor);
+		cellStyle.setAttributeValue(CellStyling.FOREGROUND_COLOR, this.anchorFgColor);
+		cellStyle.setAttributeValue(CellStyling.BORDER_STYLE, this.anchorBorderStyle);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
+				DisplayMode.SELECTED, SelectionStyleLabels.SELECTION_ANCHOR_STYLE );
+	}
+	
+	protected void configureSelectionAnchorGridLineStyle(final ConfigRegistry configRegistry) {
+		final BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.BORDER_STYLE, this.anchorGridBorderStyle);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
+				DisplayMode.SELECTED, SelectionStyleLabels.SELECTION_ANCHOR_GRID_LINE_STYLE );
+	}
+	
+	protected void configureHeaderHasSelectionStyle(final ConfigRegistry configRegistry) {
+		final BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.FOREGROUND_COLOR, this.selectedHeaderFgColor);
+		cellStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR, this.selectedHeaderBgColor);
+		cellStyle.setAttributeValue(CellStyling.FONT, this.selectedHeaderFont);
+		cellStyle.setAttributeValue(CellStyling.BORDER_STYLE, this.selectedHeaderBorderStyle);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
+				DisplayMode.SELECTED, GridLabels.COLUMN_HEADER );
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
+				DisplayMode.SELECTED, GridLabels.CORNER );
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
+				DisplayMode.SELECTED, GridLabels.ROW_HEADER );
+	}
+	
+	protected void configureHeaderFullySelectedStyle(final ConfigRegistry configRegistry) {
+		// Header fully selected
+		final BasicStyle cellStyle= new BasicStyle();
+		cellStyle.setAttributeValue(CellStyling.BACKGROUND_COLOR, GUIHelper.COLOR_WIDGET_NORMAL_SHADOW);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
+				DisplayMode.SELECTED, SelectionStyleLabels.COLUMN_FULLY_SELECTED_STYLE);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_STYLE, cellStyle,
+				DisplayMode.SELECTED, SelectionStyleLabels.ROW_FULLY_SELECTED_STYLE);
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/RowOnlySelectionBindings.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/RowOnlySelectionBindings.java
index a0ec2a8c..69d20d73 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/RowOnlySelectionBindings.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/RowOnlySelectionBindings.java
@@ -15,8 +15,8 @@ package org.eclipse.statet.ecommons.waltable.selection.config;
 
 import org.eclipse.swt.SWT;
 
-import org.eclipse.statet.ecommons.waltable.selection.action.RowSelectionDragMode;
-import org.eclipse.statet.ecommons.waltable.selection.action.SelectRowAction;
+import org.eclipse.statet.ecommons.waltable.selection.ui.action.RowSelectionDragMode;
+import org.eclipse.statet.ecommons.waltable.selection.ui.action.SelectRowAction;
 import org.eclipse.statet.ecommons.waltable.ui.action.IDragMode;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/RowOnlySelectionConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/RowOnlySelectionConfiguration.java
index 2b4312b3..0e93ca91 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/config/RowOnlySelectionConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/config/RowOnlySelectionConfiguration.java
@@ -14,13 +14,12 @@
 package org.eclipse.statet.ecommons.waltable.selection.config;
 
 import org.eclipse.statet.ecommons.waltable.config.AbstractLayerConfiguration;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEventHandler;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 
 
 /**
  * Configure the move selection behavior so that we always move by a row.
- * Add {@link ILayerEventHandler} to preserve row selection.
+ * Add {@link LayerEventHandler} to preserve row selection.
  * 
  * @see DefaultMoveSelectionConfiguration
  */
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/AbstractSelectDimPositionsCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/AbstractSelectDimPositionsCommand.java
index 537645f8..f4a62f06 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/AbstractSelectDimPositionsCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/AbstractSelectDimPositionsCommand.java
@@ -12,20 +12,23 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
 import java.util.Collection;
 import java.util.Collections;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionsCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.LayerUtil;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionsCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerUtils;
 
 
 /**
  * Abstract command to select column(s)/row(s).
  */
+@NonNullByDefault
 public abstract class AbstractSelectDimPositionsCommand extends AbstractDimPositionsCommand {
 	
 	
@@ -34,18 +37,18 @@ public abstract class AbstractSelectDimPositionsCommand extends AbstractDimPosit
 	private long positionToReveal;
 	
 	
-	public AbstractSelectDimPositionsCommand(final ILayerDim dim,
+	public AbstractSelectDimPositionsCommand(final LayerDim layerDim,
 			final long position,
 			final int selectionFlags) {
-		this(dim, position,
+		this(layerDim, position,
 				Collections.singletonList(new LRange(position)),
 				position, selectionFlags );
 	}
 	
-	public AbstractSelectDimPositionsCommand(final ILayerDim dim,
+	public AbstractSelectDimPositionsCommand(final LayerDim layerDim,
 			final long refPosition, final Collection<LRange> positions,
 			final long positionToReveal, final int selectionFlags) {
-		super(dim, refPosition, positions);
+		super(layerDim, refPosition, positions);
 		
 		this.positionToReveal= positionToReveal;
 		this.selectionFlags= selectionFlags;
@@ -69,13 +72,13 @@ public abstract class AbstractSelectDimPositionsCommand extends AbstractDimPosit
 	
 	
 	@Override
-	protected boolean convertToTargetLayer(final ILayerDim dim, final long refPosition,
-			final ILayerDim targetDim) {
+	protected boolean convertToTargetLayer(final LayerDim dim, final long refPosition,
+			final LayerDim targetDim) {
 		if (super.convertToTargetLayer(dim, refPosition, targetDim)) {
 			if (this.positionToReveal != Long.MIN_VALUE) {
 				this.positionToReveal= (this.positionToReveal == refPosition) ?
 						getRefPosition() :
-						LayerUtil.convertPosition(dim, refPosition, this.positionToReveal,
+						LayerUtils.convertPosition(dim, refPosition, this.positionToReveal,
 								targetDim );
 			}
 			return true;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/AbstractSelectRelativeCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/AbstractSelectRelativeCommand.java
index a5b02eb8..9da74ff7 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/AbstractSelectRelativeCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/AbstractSelectRelativeCommand.java
@@ -12,36 +12,30 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractRelativeCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-
-public abstract class AbstractSelectRelativeCommand extends AbstractRelativeCommand {
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractRelativeCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
 
 
+@NonNullByDefault
+public abstract class AbstractSelectRelativeCommand extends AbstractRelativeCommand {
+	
+	
 	private final int selectionFlags;
-
-
+	
+	
 	protected AbstractSelectRelativeCommand(final Direction direction, final long stepCount, final int selectionFlags) {
 		super(direction, stepCount);
 		
 		this.selectionFlags= selectionFlags;
 	}
-
-	protected AbstractSelectRelativeCommand(final AbstractSelectRelativeCommand command) {
-		super(command);
-		
-		this.selectionFlags= command.selectionFlags;
-	}
-
-	@Override
-	public abstract AbstractSelectRelativeCommand cloneCommand();
-
-
+	
+	
 	public int getSelectionFlags() {
 		return this.selectionFlags;
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionModel.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/BasicSelectionModel.java
index c0020998..48357287 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionModel.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/BasicSelectionModel.java
@@ -11,7 +11,9 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
 
 import java.util.ArrayList;
 import java.util.LinkedList;
@@ -19,11 +21,14 @@ import java.util.List;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 /**
@@ -37,12 +42,13 @@ import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
  * 
  * @see SelectionLayer
  */
-public class SelectionModel implements ISelectionModel {
+@NonNullByDefault
+public class BasicSelectionModel implements SelectionModel {
 	
 	
 	//-- Utility --//
 	
-	private static final LRectangle getLeftSelection(final LRectangle intersection, final LRectangle selection) {
+	private static final @Nullable LRectangle getLeftSelection(final LRectangle intersection, final LRectangle selection) {
 		if (intersection.x > selection.x) {
 			return new LRectangle(selection.x, selection.y,
 					intersection.x - selection.x, selection.height);
@@ -50,7 +56,7 @@ public class SelectionModel implements ISelectionModel {
 		return null;
 	}
 	
-	private static final LRectangle getRightSelection(final LRectangle intersection, final LRectangle selection) {
+	private static final @Nullable LRectangle getRightSelection(final LRectangle intersection, final LRectangle selection) {
 		final long newX= intersection.x + intersection.width;
 		if (newX < selection.x + selection.width) {
 			return new LRectangle(newX, selection.y,
@@ -59,7 +65,7 @@ public class SelectionModel implements ISelectionModel {
 		return null;
 	}
 	
-	private static final LRectangle getTopSelection(final LRectangle intersection, final LRectangle selection) {
+	private static final @Nullable LRectangle getTopSelection(final LRectangle intersection, final LRectangle selection) {
 		if (intersection.y > selection.y) {
 			return new LRectangle(selection.x, selection.y,
 					selection.width, intersection.y - selection.y);
@@ -67,7 +73,7 @@ public class SelectionModel implements ISelectionModel {
 		return null;
 	}
 	
-	private static final LRectangle getBottomSelection(final LRectangle intersection, final LRectangle selection) {
+	private static final @Nullable LRectangle getBottomSelection(final LRectangle intersection, final LRectangle selection) {
 		final long newY= intersection.y + intersection.height;
 		if (newY < selection.y + selection.height) {
 			return new LRectangle(selection.x, newY,
@@ -77,7 +83,7 @@ public class SelectionModel implements ISelectionModel {
 	}
 	
 	
-	private final ILayer selectionLayer;
+	private final Layer selectionLayer;
 	
 	private boolean multipleSelectionAllowed;
 	
@@ -85,15 +91,12 @@ public class SelectionModel implements ISelectionModel {
 	private final ReadWriteLock selectionsLock;
 	
 	
-	public SelectionModel(/*@NotNull*/ final ILayer selectionLayer) {
+	public BasicSelectionModel(final Layer selectionLayer) {
 		this(selectionLayer, true);
 	}
 	
-	public SelectionModel(/*@NotNull*/ final ILayer selectionLayer, final boolean multipleSelectionAllowed) {
-		if (selectionLayer == null) {
-			throw new NullPointerException("selectionLayer"); //$NON-NLS-1$
-		}
-		this.selectionLayer= selectionLayer;
+	public BasicSelectionModel(final Layer selectionLayer, final boolean multipleSelectionAllowed) {
+		this.selectionLayer= nonNullAssert(selectionLayer);
 		this.multipleSelectionAllowed= multipleSelectionAllowed;
 		
 		this.selections= new LinkedList<>();
@@ -142,7 +145,8 @@ public class SelectionModel implements ISelectionModel {
 							}
 							
 							itemsToRemove.add(r);
-						} else if (intersection.equals(selection)) {
+						}
+						else if (intersection.equals(selection)) {
 							// selection is a subset of r
 							break;
 						}
@@ -152,7 +156,8 @@ public class SelectionModel implements ISelectionModel {
 				if (itemsToRemove != null) {
 					this.selections.removeAll(itemsToRemove);
 				}
-			} else {
+			}
+			else {
 				this.selections.clear();
 				//as no multiple selection is allowed, ensure that only one column 
 				//and one row will be selected
@@ -161,7 +166,8 @@ public class SelectionModel implements ISelectionModel {
 			}
 			
 			this.selections.add(selection);
-		} finally {
+		}
+		finally {
 			this.selectionsLock.writeLock().unlock();
 		}
 	}
@@ -171,7 +177,8 @@ public class SelectionModel implements ISelectionModel {
 		this.selectionsLock.writeLock().lock();
 		try {
 			this.selections.clear();
-		} finally {
+		}
+		finally {
 			this.selectionsLock.writeLock().unlock();
 		}
 	}
@@ -219,7 +226,8 @@ public class SelectionModel implements ISelectionModel {
 			this.selectionsLock.writeLock().lock();
 			try {
 				this.selections.removeAll(removedItems);
-			} finally {
+			}
+			finally {
 				this.selectionsLock.writeLock().unlock();
 			}
 			
@@ -230,7 +238,8 @@ public class SelectionModel implements ISelectionModel {
 			this.selectionsLock.writeLock().lock();
 			try {
 				this.selections.addAll(addedItems);
-			} finally {
+			}
+			finally {
 				this.selectionsLock.writeLock().unlock();
 			}
 			
@@ -244,7 +253,8 @@ public class SelectionModel implements ISelectionModel {
 		this.selectionsLock.readLock().lock();
 		try {
 			return this.selections.isEmpty();
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
@@ -257,7 +267,7 @@ public class SelectionModel implements ISelectionModel {
 	// Cell features
 	
 	@Override
-	public boolean isCellPositionSelected(final ILayerCell cell) {
+	public boolean isCellPositionSelected(final LayerCell cell) {
 		this.selectionsLock.readLock().lock();
 		try {
 			final LRectangle cellRectangle= new LRectangle(
@@ -273,7 +283,8 @@ public class SelectionModel implements ISelectionModel {
 			}
 			
 			return false;
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
@@ -294,7 +305,8 @@ public class SelectionModel implements ISelectionModel {
 			}
 			
 			return selected;
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
@@ -314,7 +326,8 @@ public class SelectionModel implements ISelectionModel {
 			}
 			
 			return false;
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
@@ -338,7 +351,8 @@ public class SelectionModel implements ISelectionModel {
 			}
 			
 			return selected;
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
@@ -351,7 +365,8 @@ public class SelectionModel implements ISelectionModel {
 			
 			return ((rowCount > 0)
 					&& isColumnPositionFullySelected(columnPosition, rowCount) );
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
@@ -391,7 +406,8 @@ public class SelectionModel implements ISelectionModel {
 			}
 			
 			return selected;
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
@@ -411,7 +427,8 @@ public class SelectionModel implements ISelectionModel {
 			}
 			
 			return false;
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
@@ -449,7 +466,8 @@ public class SelectionModel implements ISelectionModel {
 			
 			return ((columnCount > 0)
 					&& isRowPositionFullySelected(rowPosition, columnCount) );
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
@@ -475,7 +493,8 @@ public class SelectionModel implements ISelectionModel {
 		this.selectionsLock.readLock().lock();
 		try {
 			return this.selections.toString();
-		} finally {
+		}
+		finally {
 			this.selectionsLock.readLock().unlock();
 		}
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/CellSelectionEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/CellSelectionEvent.java
index 052e086d..343f247d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/CellSelectionEvent.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/CellSelectionEvent.java
@@ -11,35 +11,44 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.event.CellVisualChangeEvent;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.CellVisualChangeEvent;
 
-public class CellSelectionEvent extends CellVisualChangeEvent implements ISelectionEvent {
+
+@NonNullByDefault
+public class CellSelectionEvent extends CellVisualChangeEvent implements SelectionEvent {
+	
 	
 	private final SelectionLayer selectionLayer;
 	
 	private final boolean revealCell;
 	
 	
-	public CellSelectionEvent(final SelectionLayer selectionLayer, final long columnPosition, final long rowPosition,
+	public CellSelectionEvent(final SelectionLayer selectionLayer,
+			final long columnPosition, final long rowPosition,
 			final boolean revealCell) {
 		super(selectionLayer, columnPosition, rowPosition);
 		this.selectionLayer= selectionLayer;
 		this.revealCell= revealCell;
 	}
 	
-	protected CellSelectionEvent(final CellSelectionEvent event) {
-		super(event);
-		this.selectionLayer= event.selectionLayer;
-		this.revealCell= event.revealCell;
+	protected CellSelectionEvent(final SelectionLayer selectionLayer,
+			final Layer layer, final long columnPosition, final long rowPosition, final boolean revealCell) {
+		super(layer, columnPosition, rowPosition);
+		this.selectionLayer= selectionLayer;
+		this.revealCell= revealCell;
 	}
 	
 	@Override
-	public CellSelectionEvent cloneEvent() {
-		return new CellSelectionEvent(this);
+	protected @Nullable CellSelectionEvent toLayer(final Layer targetLayer,
+			final long columnPosition, final long rowPosition) {
+		return new CellSelectionEvent(this.selectionLayer,
+				targetLayer, columnPosition, rowPosition, this.revealCell );
 	}
 	
 	
@@ -52,12 +61,4 @@ public class CellSelectionEvent extends CellVisualChangeEvent implements ISelect
 		return this.revealCell;
 	}
 	
-	@Override
-	public boolean convertToLocal(final ILayer localLayer) {
-		if(this.columnPosition == SelectionLayer.NO_SELECTION || this.rowPosition == SelectionLayer.NO_SELECTION){
-			return true;
-		}
-		return super.convertToLocal(localLayer);
-	}
-	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/ClearAllSelectionsCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/ClearAllSelectionsCommand.java
index 3e34356d..12243a5e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/ClearAllSelectionsCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/ClearAllSelectionsCommand.java
@@ -11,17 +11,20 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-
-public class ClearAllSelectionsCommand extends AbstractContextFreeCommand {
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
 
+@NonNullByDefault
+public class ClearAllSelectionsCommand extends AbstractContextFreeCommand {
+	
+	
 	public ClearAllSelectionsCommand() {
 		super();
 	}
-
-
+	
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/DimSelectionEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/DimSelectionEvent.java
new file mode 100644
index 00000000..59b04e82
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/DimSelectionEvent.java
@@ -0,0 +1,81 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.selection.core;
+
+import static org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer.NO_SELECTION;
+
+import java.util.List;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.DimPositionsVisualChangeEvent;
+
+
+@NonNullByDefault
+public class DimSelectionEvent extends DimPositionsVisualChangeEvent implements SelectionEvent {
+	
+	
+	private final SelectionLayer selectionLayer;
+	
+	private final long positionToReveal;
+	
+	
+	public DimSelectionEvent(final SelectionLayer selectionLayer, final Orientation orientation,
+			final long position, final boolean revealPosition) {
+		this(selectionLayer, orientation, new LRangeList(position),
+				(revealPosition) ? position : NO_SELECTION );
+	}
+	
+	public DimSelectionEvent(final SelectionLayer selectionLayer, final Orientation orientation,
+			final List<LRange> positions, final long positionToReveal) {
+		super(selectionLayer.getDim(orientation), positions);
+		this.selectionLayer= selectionLayer;
+		this.positionToReveal= positionToReveal;
+	}
+	
+	protected DimSelectionEvent(final SelectionLayer selectionLayer, final LayerDim layerDim,
+			final List<LRange> positions, final long positionToReveal) {
+		super(layerDim, positions);
+		this.selectionLayer= selectionLayer;
+		this.positionToReveal= positionToReveal;
+	}
+	
+	@Override
+	protected @Nullable DimPositionsVisualChangeEvent toLayer(final LayerDim targetLayerDim,
+			final List<LRange> positions) {
+		final long positionToReveal= (this.positionToReveal != NO_SELECTION) ?
+				targetLayerDim.underlyingToLocalPosition(
+						getLayerDim(), this.positionToReveal ) :
+				NO_SELECTION;
+		
+		return new DimSelectionEvent(this.selectionLayer, targetLayerDim,
+				positions, positionToReveal );
+	}
+	
+	
+	@Override
+	public SelectionLayer getSelectionLayer() {
+		return this.selectionLayer;
+	}
+	
+	public long getPositionToReveal() {
+		return this.positionToReveal;
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/EmptySelectionEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/EmptySelectionEvent.java
new file mode 100644
index 00000000..87dd6fe7
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/EmptySelectionEvent.java
@@ -0,0 +1,57 @@
+/*=============================================================================#
+ # Copyright (c) 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.selection.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.GeneralVisualChangeEvent;
+
+
+@NonNullByDefault
+public class EmptySelectionEvent extends GeneralVisualChangeEvent implements SelectionEvent {
+	
+	
+	private final SelectionLayer selectionLayer;
+	
+	
+	public EmptySelectionEvent(final SelectionLayer selectionLayer) {
+		super(selectionLayer);
+		this.selectionLayer= selectionLayer;
+	}
+	
+	protected EmptySelectionEvent(final SelectionLayer selectionLayer, final Layer layer) {
+		super(layer);
+		this.selectionLayer= selectionLayer;
+	}
+	
+	@Override
+	public @Nullable GeneralVisualChangeEvent toLayer(final Layer targetLayer) {
+		if (targetLayer == getLayer()) {
+			return this;
+		}
+		
+		return new EmptySelectionEvent(this.selectionLayer, targetLayer);
+	}
+	
+	
+	@Override
+	public SelectionLayer getSelectionLayer() {
+		return this.selectionLayer;
+	}
+	
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectAllCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectAllCommand.java
index 64bb22bb..06c2e683 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectAllCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectAllCommand.java
@@ -11,16 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-
-public class SelectAllCommand extends AbstractContextFreeCommand {
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
 
+@NonNullByDefault
+public class SelectAllCommand extends AbstractContextFreeCommand {
+	
+	
 	public SelectAllCommand() {
 	}
-
-
+	
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectCellCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectCellCommand.java
index f204586a..d2b23714 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectCellCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectCellCommand.java
@@ -11,10 +11,12 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 import org.eclipse.statet.ecommons.waltable.command.AbstractPositionCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
 /**
@@ -25,46 +27,47 @@ import org.eclipse.statet.ecommons.waltable.layer.ILayer;
  * clicked. Do not pass it anything else or you will introduce very subtle and very difficult to debug bugs into the 
  * code and then we will have to pay you a visit on one random Sunday morning when you least expect it.</strong>
  */
+@NonNullByDefault
 public class SelectCellCommand extends AbstractPositionCommand {
-
-
+	
+	
 	private final int selectionFlags;
-
+	
 	private final boolean revealCell;
-
-
-	public SelectCellCommand(final ILayer layer, final long columnPosition, final long rowPosition,
+	
+	
+	public SelectCellCommand(final Layer layer, final long columnPosition, final long rowPosition,
 			final int selectionFlags) {
 		this(layer, columnPosition, rowPosition, selectionFlags, true);
 	}
-
-	public SelectCellCommand(final ILayer layer, final long columnPosition, final long rowPosition,
+	
+	public SelectCellCommand(final Layer layer, final long columnPosition, final long rowPosition,
 			final int selectionFlags, final boolean revealCell) {
 		super(layer, columnPosition, rowPosition);
 		
 		this.selectionFlags= selectionFlags;
 		this.revealCell= revealCell;
 	}
-
+	
 	protected SelectCellCommand(final SelectCellCommand command) {
 		super(command);
 		
 		this.selectionFlags= command.selectionFlags;
 		this.revealCell= command.revealCell;
 	}
-
+	
 	@Override
 	public SelectCellCommand cloneCommand() {
 		return new SelectCellCommand(this);
 	}
-
-
+	
+	
 	public int getSelectionFlags() {
 		return this.selectionFlags;
 	}
-
+	
 	public boolean getRevealCell() {
 		return this.revealCell;
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectCellCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectCellCommandHandler.java
index 0dc296bf..a98afd94 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectCellCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectCellCommandHandler.java
@@ -11,23 +11,26 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-
-public class SelectCellCommandHandler extends AbstractLayerCommandHandler<SelectCellCommand> {
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
 
 
+@NonNullByDefault
+public class SelectCellCommandHandler extends AbstractLayerCommandHandler<SelectCellCommand> {
+	
+	
 	private final SelectionLayer selectionLayer;
-
-
+	
+	
 	public SelectCellCommandHandler(final SelectionLayer selectionLayer) {
 		this.selectionLayer= selectionLayer;
 	}
-
-
+	
+	
 	@Override
 	public Class<SelectCellCommand> getCommandClass() {
 		return SelectCellCommand.class;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectDimPositionsCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectDimPositionsCommand.java
index 17f6d8fa..92742986 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectDimPositionsCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectDimPositionsCommand.java
@@ -11,18 +11,21 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
 import java.util.Collection;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionsCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.LayerUtil;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionsCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerUtils;
 
+
+@NonNullByDefault
 public class SelectDimPositionsCommand extends AbstractDimPositionsCommand {
 	
 	
@@ -33,14 +36,14 @@ public class SelectDimPositionsCommand extends AbstractDimPositionsCommand {
 	private long positionToReveal;
 	
 	
-	public SelectDimPositionsCommand(final ILayerDim layerDim,
+	public SelectDimPositionsCommand(final LayerDim layerDim,
 			final long position, final long orthogonalPosition,
 			final int selectionFlags) {
 		this(layerDim, position, new LRangeList(position), orthogonalPosition, selectionFlags,
 				position );
 	}
 	
-	public SelectDimPositionsCommand(final ILayerDim layerDim,
+	public SelectDimPositionsCommand(final LayerDim layerDim,
 			final long refPosition, final Collection<LRange> positions,
 			final long orthogonalPosition, final int selectionFlags, final long positionToReveal) {
 		super(layerDim, refPosition, positions);
@@ -65,16 +68,16 @@ public class SelectDimPositionsCommand extends AbstractDimPositionsCommand {
 	
 	
 	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
-		final ILayerDim layerDim= getDim();
-		final long targetOrthogonalPosition= LayerUtil.convertPosition(
+	public boolean convertToTargetLayer(final Layer targetLayer) {
+		final LayerDim layerDim= getDim();
+		final long targetOrthogonalPosition= LayerUtils.convertPosition(
 				layerDim.getLayer().getDim(getOrientation().getOrthogonal()),
 				this.orthogonalPosition, this.orthogonalPosition,
 				targetLayer.getDim(getOrientation().getOrthogonal()) );
-		if (targetOrthogonalPosition != ILayerDim.POSITION_NA
+		if (targetOrthogonalPosition != LayerDim.POSITION_NA
 				&& super.convertToTargetLayer(targetLayer) ) {
 			this.orthogonalPosition= targetOrthogonalPosition;
-			this.positionToReveal= LayerUtil.convertPosition(layerDim,
+			this.positionToReveal= LayerUtils.convertPosition(layerDim,
 					this.positionToReveal, this.positionToReveal,
 					targetLayer.getDim(getOrientation()) );
 			return true;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectDimPositionsCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectDimPositionsCommandHandler.java
index f1fffc9d..d5a344b6 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectDimPositionsCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectDimPositionsCommandHandler.java
@@ -11,16 +11,20 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
 
+
+@NonNullByDefault
 public class SelectDimPositionsCommandHandler extends AbstractLayerCommandHandler<SelectDimPositionsCommand> {
 	
 	
@@ -63,7 +67,7 @@ public class SelectDimPositionsCommandHandler extends AbstractLayerCommandHandle
 			final LRectangle columnRegion= new LRectangle(
 					singleColumnPosition, 0, 1, this.selectionLayer.getRowCount());
 			this.selectionLayer.clearSelection(columnRegion);
-			this.selectionLayer.fireLayerEvent(new ColumnSelectionEvent(this.selectionLayer,
+			this.selectionLayer.fireLayerEvent(new DimSelectionEvent(this.selectionLayer, HORIZONTAL,
 					singleColumnPosition, (columnPositionToReveal == singleColumnPosition) ));
 			return;
 		}
@@ -118,7 +122,7 @@ public class SelectDimPositionsCommandHandler extends AbstractLayerCommandHandle
 		}
 		
 		// TODO correct change set
-		this.selectionLayer.fireLayerEvent(new ColumnSelectionEvent(this.selectionLayer,
+		this.selectionLayer.fireLayerEvent(new DimSelectionEvent(this.selectionLayer, HORIZONTAL,
 				columnPositions, columnPositionToReveal ));
 	}
 	
@@ -133,7 +137,8 @@ public class SelectDimPositionsCommandHandler extends AbstractLayerCommandHandle
 			final LRectangle columnRegion= new LRectangle(
 					0, singleRowPosition, this.selectionLayer.getColumnCount(), 1);
 			this.selectionLayer.clearSelection(columnRegion);
-			this.selectionLayer.fireLayerEvent(new RowSelectionEvent(this.selectionLayer, singleRowPosition, false));
+			this.selectionLayer.fireLayerEvent(new DimSelectionEvent(this.selectionLayer, VERTICAL,
+					singleRowPosition, false ));
 			return;
 		}
 		selectRows(columnPosition, rowPositions, selectionFlags, rowPositionToShow);
@@ -192,7 +197,8 @@ public class SelectDimPositionsCommandHandler extends AbstractLayerCommandHandle
 			this.selectionLayer.lastSelectedCell.rowPosition= lastPosition;
 		}
 		
-		this.selectionLayer.fireLayerEvent(new RowSelectionEvent(this.selectionLayer, changedRowRanges, rowPositionToShow));
+		this.selectionLayer.fireLayerEvent(new DimSelectionEvent(this.selectionLayer, VERTICAL,
+				changedRowRanges, rowPositionToShow ));
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectRelativeCellCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectRelativeCellCommand.java
index df6cdb83..7f12d1a4 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectRelativeCellCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectRelativeCellCommand.java
@@ -12,14 +12,17 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-
-public class SelectRelativeCellCommand extends AbstractSelectRelativeCommand {
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
 
 
+@NonNullByDefault
+public class SelectRelativeCellCommand extends AbstractSelectRelativeCommand {
+	
+	
 	public SelectRelativeCellCommand(final Direction direction) {
 		this(direction, 1, 0);
 	}
@@ -27,15 +30,6 @@ public class SelectRelativeCellCommand extends AbstractSelectRelativeCommand {
 	public SelectRelativeCellCommand(final Direction direction, final long stepCount, final int selectionFlags) {
 		super(direction, stepCount, selectionFlags);
 	}
-
-	protected SelectRelativeCellCommand(final SelectRelativeCellCommand command) {
-		super(command);
-	}
-
-	@Override
-	public SelectRelativeCellCommand cloneCommand() {
-		return new SelectRelativeCellCommand(this);
-	}
-
-
+	
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectRelativeCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectRelativeCommandHandler.java
index 3757c070..e58373aa 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectRelativeCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectRelativeCommandHandler.java
@@ -12,35 +12,38 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
-
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-public class SelectRelativeCommandHandler extends AbstractLayerCommandHandler<SelectRelativeCellCommand> {
+import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
 
 
+@NonNullByDefault
+public class SelectRelativeCommandHandler implements LayerCommandHandler<SelectRelativeCellCommand> {
+	
+	
 	protected final SelectionLayer selectionLayer;
-
-
+	
+	
 	public SelectRelativeCommandHandler(final SelectionLayer selectionLayer) {
 		this.selectionLayer= selectionLayer;
 	}
-
-
+	
+	
 	@Override
 	public Class<SelectRelativeCellCommand> getCommandClass() {
 		return SelectRelativeCellCommand.class;
 	}
-
-
+	
+	
 	@Override
-	protected boolean doCommand(final SelectRelativeCellCommand command) {
+	public boolean executeCommand(final SelectRelativeCellCommand command) {
 		select(command);
 		return true;
 	}
-
+	
 	protected boolean select(final SelectRelativeCellCommand command) {
 		long row;
 		long column;
@@ -141,5 +144,5 @@ public class SelectRelativeCommandHandler extends AbstractLayerCommandHandler<Se
 		this.selectionLayer.fireCellSelectionEvent(column, row, true);
 		return true;
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/ISelectionEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionEvent.java
index 4e12c7ab..84364931 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/ISelectionEvent.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionEvent.java
@@ -11,14 +11,18 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 
 /**
  * Marker interface for selection events.
  */
-public interface ISelectionEvent {
-
-	public SelectionLayer getSelectionLayer();
+@NonNullByDefault
+public interface SelectionEvent {
+	
+	
+	SelectionLayer getSelectionLayer();
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/IStyle.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionFlags.java
index 494ecc29..94d43fb0 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/style/IStyle.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionFlags.java
@@ -11,17 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.style;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-/**
- * Used to store attributes reflecting a (usually display) style.
- */
-public interface IStyle {
+
+@NonNullByDefault
+public class SelectionFlags {
 	
 	
-	<T> T getAttributeValue(ConfigAttribute<T> styleAttribute);
+	/** Extend current selection */
+	public static final int RANGE_SELECTION= 1 << 17; // SWT.SHIFT;
+	/** Retain or toggle */
+	public static final int RETAIN_SELECTION= 1 << 18; // SWT.CTRL;
 	
-	<T> void setAttributeValue(ConfigAttribute<T> styleAttribute, T value);
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionLayer.java
index e12ae703..dd991760 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionLayer.java
@@ -11,9 +11,9 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -21,72 +21,74 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
-import org.eclipse.statet.ecommons.waltable.coordinate.ILValueIterator;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
+import org.eclipse.statet.jcommons.collections.LongIterator;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
 import org.eclipse.statet.ecommons.waltable.coordinate.PositionCoordinate;
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerPainter;
 import org.eclipse.statet.ecommons.waltable.edit.EditSelectionCommandHandler;
-import org.eclipse.statet.ecommons.waltable.layer.ForwardLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ForwardLayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCellDim;
-import org.eclipse.statet.ecommons.waltable.painter.layer.ILayerPainter;
 import org.eclipse.statet.ecommons.waltable.selection.config.DefaultSelectionLayerConfiguration;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.selection.swt.SelectionLayerPainter;
 import org.eclipse.statet.ecommons.waltable.style.SelectionStyleLabels;
 
 
 /**
  * Enables selection of column, rows, cells etc. on the table.
  * Also responds to UI bindings by changing the current selection.
- * Internally it uses the {@link ISelectionModel} to track the selection state.<br/>
+ * Internally it uses the {@link SelectionModel} to track the selection state.<br/>
  * 
  * @see DefaultSelectionLayerConfiguration
- * @see Direction
  */
-public class SelectionLayer extends ForwardLayer {
+@NonNullByDefault
+public class SelectionLayer extends ForwardLayer<ForwardLayerDim<? extends SelectionLayer>> {
 	
 	
 	public static final int MOVE_ALL= -1;
 	public static final long NO_SELECTION= Long.MIN_VALUE;
 	
 	
-	protected ISelectionModel selectionModel;
-	protected ILayer underlyingLayer;
+	protected SelectionModel selectionModel;
+	protected Layer underlyingLayer;
 	protected final PositionCoordinate lastSelectedCell;
 	protected final PositionCoordinate selectionAnchor;
-	protected LRectangle lastSelectedRegion;
+	protected @Nullable LRectangle lastSelectedRegion;
 	
 	private final SelectCellCommandHandler selectCellCommandHandler;
 	private final SelectDimPositionsCommandHandler selectDimPositionsCommandHandler;
 	
 	
-	public SelectionLayer(final ILayer underlyingLayer) {
+	public SelectionLayer(final Layer underlyingLayer) {
 		this(underlyingLayer, null, true);
 	}
 	
-	public SelectionLayer(final ILayer underlyingLayer, final boolean useDefaultConfiguration) {
+	public SelectionLayer(final Layer underlyingLayer, final boolean useDefaultConfiguration) {
 		this(underlyingLayer, null, useDefaultConfiguration);
 	}
 	
 	
-	public SelectionLayer(final ILayer underlyingLayer, final ISelectionModel selectionModel, final boolean useDefaultConfiguration) {
+	public SelectionLayer(final Layer underlyingLayer, final SelectionModel selectionModel, final boolean useDefaultConfiguration) {
 		this(underlyingLayer, selectionModel, useDefaultConfiguration, true);
 	}
 	
-	public SelectionLayer(final ILayer underlyingLayer, final ISelectionModel selectionModel, final boolean useDefaultConfiguration, final boolean registerDefaultEventHandler) {
+	public SelectionLayer(final Layer underlyingLayer, final SelectionModel selectionModel, final boolean useDefaultConfiguration, final boolean registerDefaultEventHandler) {
 		super(underlyingLayer);
 		this.underlyingLayer= underlyingLayer;
 		
-		setLayerPainter(new SelectionLayerPainter());
-		
-		this.selectionModel= selectionModel != null ? selectionModel : new SelectionModel(this);
+		this.selectionModel= selectionModel != null ? selectionModel : new BasicSelectionModel(this);
 		
 		this.lastSelectedCell= new PositionCoordinate(this, NO_SELECTION, NO_SELECTION);
 		this.selectionAnchor= new PositionCoordinate(this, NO_SELECTION, NO_SELECTION);
@@ -94,6 +96,8 @@ public class SelectionLayer extends ForwardLayer {
 		this.selectCellCommandHandler= new SelectCellCommandHandler(this);
 		this.selectDimPositionsCommandHandler= new SelectDimPositionsCommandHandler(this);
 		
+		init();
+		
 		registerCommandHandlers();
 		
 		if(registerDefaultEventHandler){
@@ -104,18 +108,24 @@ public class SelectionLayer extends ForwardLayer {
 		}
 	}
 	
+	@Override
+	protected ForwardLayerDim<? extends SelectionLayer> createDim(final Orientation orientation) {
+		return new ForwardLayerDim<>(this, getUnderlyingLayer().getDim(orientation));
+	}
 	
-	public ISelectionModel getSelectionModel() {
-		return this.selectionModel;
+	
+	@Override
+	protected LayerPainter createPainter() {
+		return new SelectionLayerPainter();
 	}
 	
-	public void setSelectionModel(final ISelectionModel selectionModel) {
-		this.selectionModel= selectionModel;
+	
+	public SelectionModel getSelectionModel() {
+		return this.selectionModel;
 	}
 	
-	@Override
-	public ILayerPainter getLayerPainter() {
-		return this.layerPainter;
+	public void setSelectionModel(final SelectionModel selectionModel) {
+		this.selectionModel= selectionModel;
 	}
 	
 	protected void addSelection(final LRectangle selection) {
@@ -132,7 +142,7 @@ public class SelectionLayer extends ForwardLayer {
 	public void clear() {
 		clearSelections();
 		
-		fireLayerEvent(new CellSelectionEvent(this, NO_SELECTION, NO_SELECTION, false));
+		fireLayerEvent(new EmptySelectionEvent(this));
 	}
 	
 	protected void resetLastSelection() {
@@ -172,8 +182,8 @@ public class SelectionLayer extends ForwardLayer {
 	// Cell features
 	
 	public boolean isCellPositionSelected(final long columnPosition, final long rowPosition) {
-		final ILayerCell cell= getCellByPosition(columnPosition, rowPosition);
-		return (cell != null && cell.getDisplayMode() == DisplayMode.SELECT);
+		final LayerCell cell= getCellByPosition(columnPosition, rowPosition);
+		return (cell != null && cell.getDisplayMode() == DisplayMode.SELECTED);
 	}
 	
 	/**
@@ -196,9 +206,9 @@ public class SelectionLayer extends ForwardLayer {
 		
 		final List<PositionCoordinate> selectedCells= new ArrayList<>();
 		
-		for (final ILValueIterator columnIter= selectedColumnPositions.values().iterator(); columnIter.hasNext(); ) {
+		for (final LongIterator columnIter= selectedColumnPositions.values().iterator(); columnIter.hasNext(); ) {
 			final long columnPosition= columnIter.nextValue();
-			for (final ILValueIterator rowIter= selectedRowPositions.values().iterator(); rowIter.hasNext(); ) {
+			for (final LongIterator rowIter= selectedRowPositions.values().iterator(); rowIter.hasNext(); ) {
 				final long rowPosition= rowIter.nextValue();
 				if (isCellPositionSelected(columnPosition, rowPosition)) {
 					selectedCells.add(new PositionCoordinate(this, columnPosition, rowPosition));
@@ -214,8 +224,8 @@ public class SelectionLayer extends ForwardLayer {
 	 * the SelectionModel. Takes spanning into account.
 	 * @return The selected ILayerCells
 	 */
-	public Collection<ILayerCell> getSelectedCells() {
-		final Set<ILayerCell> selectedCells= new HashSet<>();
+	public Collection<LayerCell> getSelectedCells() {
+		final Set<LayerCell> selectedCells= new HashSet<>();
 		
 		final List<PositionCoordinate> selectedCoords= getSelectedCellPositions();
 		for (final PositionCoordinate coord : selectedCoords) {
@@ -378,21 +388,21 @@ public class SelectionLayer extends ForwardLayer {
 	// ILayer methods
 	
 	@Override
-	protected ILayerCell createCell(final ILayerCellDim hDim, final ILayerCellDim vDim,
-			final ILayerCell underlyingCell) {
+	protected LayerCell createCell(final LayerCellDim hDim, final LayerCellDim vDim,
+			final LayerCell underlyingCell) {
 		return new ForwardLayerCell(this, hDim, vDim, underlyingCell) {
 			
 			@Override
 			public DisplayMode getDisplayMode() {
 				if (SelectionLayer.this.selectionModel.isCellPositionSelected(this)) {
-					return DisplayMode.SELECT;
+					return DisplayMode.SELECTED;
 				}
 				return super.getDisplayMode();
 			}
 			
 			@Override
-			public LabelStack getConfigLabels() {
-				final LabelStack configLabels= super.getConfigLabels();
+			public LabelStack getLabels() {
+				final LabelStack configLabels= super.getLabels();
 				
 				final LRectangle cellRectangle= new LRectangle(
 						getOriginColumnPosition(),
@@ -423,14 +433,12 @@ public class SelectionLayer extends ForwardLayer {
 	}
 	
 	@Override
-	public boolean doCommand(final ILayerCommand command) {
-		if (command instanceof SelectAllCommand
-				&& command.cloneCommand().convertToTargetLayer(this)) {
+	public boolean doCommand(final LayerCommand command) {
+		if (command instanceof SelectAllCommand) {
 			selectAll();
 			return true;
 		}
-		else if (command instanceof ClearAllSelectionsCommand
-				&& command.cloneCommand().convertToTargetLayer(this)) {
+		else if (command instanceof ClearAllSelectionsCommand) {
 			clear();
 			return true;
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionLayerStructuralChangeEventHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionLayerStructuralChangeEventHandler.java
new file mode 100644
index 00000000..871b274d
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionLayerStructuralChangeEventHandler.java
@@ -0,0 +1,105 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.selection.core;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
+
+import java.util.Collection;
+import java.util.List;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerListener;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralChangeEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralDiff;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralDiff.DiffType;
+
+
+@NonNullByDefault
+public class SelectionLayerStructuralChangeEventHandler implements LayerListener {
+	
+	
+	private final SelectionModel selectionModel;
+	private final SelectionLayer selectionLayer;
+	
+	
+	public SelectionLayerStructuralChangeEventHandler(final SelectionLayer selectionLayer, final SelectionModel selectionModel) {
+		this.selectionLayer= selectionLayer;
+		this.selectionModel= selectionModel;
+	}
+	
+	
+	@Override
+	public void handleLayerEvent(final LayerEvent event) {
+		if (event instanceof StructuralChangeEvent) {
+			final var changeEvent= (StructuralChangeEvent)event;
+			if (changeEvent.isStructureChanged(HORIZONTAL)) {
+				// TODO handle column deletion
+				this.selectionLayer.clear();
+				return;
+			}
+			
+			if (changeEvent.isStructureChanged(VERTICAL)) {
+				final List<StructuralDiff> rowDiffs= changeEvent.getDiffs(VERTICAL);
+				if (rowDiffs == null) {
+					//if there are no row diffs, it is a complete refresh
+					final Collection<LRectangle> lRectangles= changeEvent.getChangedPositionRectangles();
+					for (final LRectangle lRectangle : lRectangles) {
+						final LRange changedRange= new LRange(lRectangle.y, lRectangle.y + lRectangle.height);
+						if (selectedRowModified(changedRange)) {
+							if (this.selectionLayer.getRowCount() > 0) {
+								long columnPosition= this.selectionLayer.getSelectionAnchor().columnPosition;
+								if (columnPosition == SelectionLayer.NO_SELECTION) {
+									columnPosition= 0;
+								}
+								this.selectionLayer.setSelectionToCell(columnPosition, 0, false);
+							}
+							else {
+								this.selectionLayer.clear();
+							}
+							return;
+						}
+					}
+				}
+				else {
+					//there are row diffs so we try to determine the diffs to process
+					for (final StructuralDiff diff : rowDiffs) {
+						//DiffTypeEnum.CHANGE is used for resizing and shouldn't result in clearing the selection
+						if (diff.getDiffType() != DiffType.CHANGE) {
+							if (selectedRowModified(diff.getBeforePositionRange())) {
+								this.selectionLayer.clear();
+								return;
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+	
+	private boolean selectedRowModified(final LRange changedRange){
+		final List<LRange> selectedRows= this.selectionModel.getSelectedRowPositions();
+		for (final var range : selectedRows) {
+			if (range.overlap(changedRange)){
+				return true;
+			}
+		}
+		return false;
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/ISelectionModel.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionModel.java
index 0794c789..c5896e44 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/ISelectionModel.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/core/SelectionModel.java
@@ -11,13 +11,15 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.core;
 
 import java.util.List;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRangeList;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
 
 
 /**
@@ -28,7 +30,8 @@ import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
  * A column or row is not selected and not fully selected, if the selection layer is empty
  * (any dim has size 0).</p>
  */
-public interface ISelectionModel {
+@NonNullByDefault
+public interface SelectionModel {
 	
 	
 	boolean isMultipleSelectionAllowed();
@@ -93,7 +96,7 @@ public interface ISelectionModel {
 	 * @param rowPosition the row position in the selection layer
 	 * @return <code>true</code> if the position is selected, otherwise <code>false</code>
 	 */
-	boolean isCellPositionSelected(ILayerCell cell);
+	boolean isCellPositionSelected(LayerCell cell);
 	
 	//-- Column features --//
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionLayerPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/swt/SelectionLayerPainter.java
index 2161446e..be19f504 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionLayerPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/swt/SelectionLayerPainter.java
@@ -11,7 +11,7 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection;
+package org.eclipse.statet.ecommons.waltable.selection.swt;
 
 import static org.eclipse.statet.ecommons.waltable.painter.cell.GraphicsUtils.safe;
 
@@ -23,22 +23,25 @@ import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Rectangle;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.painter.layer.GridLineCellLayerPainter;
-import org.eclipse.statet.ecommons.waltable.style.BorderStyle;
-import org.eclipse.statet.ecommons.waltable.style.CellStyleAttributes;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
-import org.eclipse.statet.ecommons.waltable.style.IStyle;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.style.BorderStyle;
+import org.eclipse.statet.ecommons.waltable.core.style.CellStyling;
+import org.eclipse.statet.ecommons.waltable.core.style.Style;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
+import org.eclipse.statet.ecommons.waltable.core.swt.painters.GridLineCellLayerPainter;
 import org.eclipse.statet.ecommons.waltable.style.SelectionStyleLabels;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
+@NonNullByDefault
 public class SelectionLayerPainter extends GridLineCellLayerPainter {
 	
 	
@@ -46,13 +49,18 @@ public class SelectionLayerPainter extends GridLineCellLayerPainter {
 	
 	private long rowPositionOffset;
 	
-	private Map<LPoint, ILayerCell> cells;
+	private Map<LPoint, LayerCell> cells;
+	
+	
+	public SelectionLayerPainter() {
+		super();
+	}
 	
 	
 	@Override
-	public void paintLayer(final ILayer natLayer, final GC gc,
+	public void paintLayer(final Layer natLayer, final GC gc,
 			final int xOffset, final int yOffset, final Rectangle pixelRectangle,
-			final IConfigRegistry configRegistry) {
+			final ConfigRegistry configRegistry) {
 		final LRectangle positionRectangle= getPositionRectangleFromPixelRectangle(natLayer, pixelRectangle);
 		this.columnPositionOffset= positionRectangle.x;
 		this.rowPositionOffset= positionRectangle.y;
@@ -73,8 +81,8 @@ public class SelectionLayerPainter extends GridLineCellLayerPainter {
 		// Draw horizontal borders
 		boolean selectedMode= false;
 		for (long columnPosition= this.columnPositionOffset; columnPosition < this.columnPositionOffset + positionRectangle.width; columnPosition++) {
-			ILayerCell previousCell= null;
-			ILayerCell currentCell= null;
+			LayerCell previousCell= null;
+			LayerCell currentCell= null;
 			for (long rowPosition= this.rowPositionOffset; rowPosition < this.rowPositionOffset + positionRectangle.height; rowPosition++) {
 				currentCell= this.cells.get(new LPoint(columnPosition, rowPosition));
 				if (currentCell != null) {
@@ -112,8 +120,8 @@ public class SelectionLayerPainter extends GridLineCellLayerPainter {
 		
 		// Draw vertical borders
 		for (long rowPosition= this.rowPositionOffset; rowPosition < this.rowPositionOffset + positionRectangle.height; rowPosition++) {
-			ILayerCell previousCell= null;
-			ILayerCell currentCell= null;
+			LayerCell previousCell= null;
+			LayerCell currentCell= null;
 			for (long columnPosition= this.columnPositionOffset; columnPosition < this.columnPositionOffset + positionRectangle.width; columnPosition++) {
 				currentCell= this.cells.get(new LPoint(columnPosition, rowPosition));
 				if (currentCell != null) {
@@ -156,7 +164,7 @@ public class SelectionLayerPainter extends GridLineCellLayerPainter {
 	}
 	
 	@Override
-	protected void paintCell(final ILayerCell cell, final GC gc, final IConfigRegistry configRegistry) {
+	protected void paintCell(final LayerCell cell, final GC gc, final ConfigRegistry configRegistry) {
 		for (long columnPosition= cell.getOriginColumnPosition(); columnPosition < cell.getOriginColumnPosition() + cell.getColumnSpan(); columnPosition++) {
 			for (long rowPosition= cell.getOriginRowPosition(); rowPosition < cell.getOriginRowPosition() + cell.getRowSpan(); rowPosition++) {
 				this.cells.put(new LPoint(columnPosition, rowPosition), cell);
@@ -166,22 +174,22 @@ public class SelectionLayerPainter extends GridLineCellLayerPainter {
 		super.paintCell(cell, gc, configRegistry);
 	}
 	
-	private boolean isSelected(final ILayerCell cell) {
-		return (cell.getDisplayMode() == DisplayMode.SELECT);
+	private boolean isSelected(final LayerCell cell) {
+		return (cell.getDisplayMode() == DisplayMode.SELECTED);
 	}
 	
-	private void applyBorderStyle(final GC gc, final IConfigRegistry configRegistry) {
+	private void applyBorderStyle(final GC gc, final ConfigRegistry configRegistry) {
 		//Note: If there is no style configured for the SelectionStyleLabels.SELECTION_ANCHOR_GRID_LINE_STYLE
 		//		label, the style configured for DisplayMode.SELECT will be retrieved by this call.
 		//		Ensure that the selection style configuration does not contain a border style configuration
 		//		to avoid strange rendering behaviour. By default there is no border configuration added,
 		//		so there shouldn't be issues with backwards compatibility. And if there are some, they can
 		//		be solved easily by adding the necessary border style configuration.
-		final IStyle cellStyle= configRegistry.getConfigAttribute(
+		final Style cellStyle= configRegistry.getAttribute(
 				CellConfigAttributes.CELL_STYLE, 
-				DisplayMode.SELECT, 
+				DisplayMode.SELECTED, 
 				SelectionStyleLabels.SELECTION_ANCHOR_GRID_LINE_STYLE);
-		final BorderStyle borderStyle= cellStyle != null ? cellStyle.getAttributeValue(CellStyleAttributes.BORDER_STYLE) : null;
+		final BorderStyle borderStyle= cellStyle != null ? cellStyle.getAttributeValue(CellStyling.BORDER_STYLE) : null;
 		
 		//if there is no border style configured, use the default one for backwards compatibility
 		if (borderStyle == null) {
@@ -190,7 +198,7 @@ public class SelectionLayerPainter extends GridLineCellLayerPainter {
 			gc.setForeground(GUIHelper.COLOR_BLACK);
 		}
 		else {
-			gc.setLineStyle(SWTUtil.toSWT(borderStyle.getLineStyle()));
+			gc.setLineStyle(SwtUtils.toSWT(borderStyle.getLineStyle()));
 			gc.setLineWidth(borderStyle.getThickness());
 			gc.setForeground(borderStyle.getColor());
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/CellSelectionDragMode.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/CellSelectionDragMode.java
index 1df988a9..f637a53a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/CellSelectionDragMode.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/CellSelectionDragMode.java
@@ -11,14 +11,14 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection.action;
+package org.eclipse.statet.ecommons.waltable.selection.ui.action;
 
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.selection.SelectCellCommand;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionFlags;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectCellCommand;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionFlags;
 import org.eclipse.statet.ecommons.waltable.ui.action.IDragMode;
 
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/RowSelectionDragMode.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/RowSelectionDragMode.java
index d94d07ff..1861b240 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/RowSelectionDragMode.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/RowSelectionDragMode.java
@@ -11,13 +11,13 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection.action;
+package org.eclipse.statet.ecommons.waltable.selection.ui.action;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.selection.SelectDimPositionsCommand;
 import org.eclipse.statet.ecommons.waltable.selection.config.RowOnlySelectionBindings;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectDimPositionsCommand;
 
 
 /**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/SelectAllAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/SelectAllAction.java
index 9639272b..f506261e 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/SelectAllAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/SelectAllAction.java
@@ -11,12 +11,12 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection.action;
+package org.eclipse.statet.ecommons.waltable.selection.ui.action;
 
 import org.eclipse.swt.events.KeyEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.selection.SelectAllCommand;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectAllCommand;
 import org.eclipse.statet.ecommons.waltable.ui.action.IKeyAction;
 
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/SelectCellAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/SelectCellAction.java
index 21405d41..2189df66 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/SelectCellAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/SelectCellAction.java
@@ -11,13 +11,14 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection.action;
+package org.eclipse.statet.ecommons.waltable.selection.ui.action;
 
+import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.selection.SelectCellCommand;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionFlags;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectCellCommand;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionFlags;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 
 
@@ -27,6 +28,18 @@ import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 public class SelectCellAction implements IMouseAction {
 	
 	
+	public static final int swt2Flags(final int swtMask) {
+		int flags= 0;
+		if ((swtMask & SWT.MOD2) != 0) {
+			flags |= SelectionFlags.RANGE_SELECTION;
+		}
+		if ((swtMask & SWT.MOD1) != 0) {
+			flags |= SelectionFlags.RETAIN_SELECTION;
+		}
+		return flags;
+	}
+	
+	
 	public SelectCellAction() {
 	}
 	
@@ -36,8 +49,9 @@ public class SelectCellAction implements IMouseAction {
 		natTable.doCommand(new SelectCellCommand(natTable,
 				natTable.getColumnPositionByX(event.x),
 				natTable.getRowPositionByY(event.y),
-				SelectionFlags.swt2Flags(event.stateMask),
+				SelectCellAction.swt2Flags(event.stateMask),
 				true ));
 	}
 	
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/SelectRowAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/SelectRowAction.java
index d9b42427..ed57a608 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/action/SelectRowAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/selection/ui/action/SelectRowAction.java
@@ -11,15 +11,14 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.selection.action;
+package org.eclipse.statet.ecommons.waltable.selection.ui.action;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.selection.SelectDimPositionsCommand;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionFlags;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectDimPositionsCommand;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 
 
@@ -38,7 +37,7 @@ public class SelectRowAction implements IMouseAction {
 		natTable.doCommand(new SelectDimPositionsCommand(natTable.getDim(VERTICAL),
 				natTable.getRowPositionByY(event.y),
 				natTable.getColumnPositionByX(event.x),
-				SelectionFlags.swt2Flags(event.stateMask) ));
+				SelectCellAction.swt2Flags(event.stateMask) ));
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/ColumnHeaderClickEventMatcher.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/ColumnHeaderClickEventMatcher.java
index 6e625329..cf1f02ce 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/ColumnHeaderClickEventMatcher.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/ColumnHeaderClickEventMatcher.java
@@ -16,10 +16,10 @@ package org.eclipse.statet.ecommons.waltable.sort;
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.MouseEventMatcher;
 import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeDetectUtil;
 import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeEnum;
@@ -32,7 +32,7 @@ import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 public class ColumnHeaderClickEventMatcher extends MouseEventMatcher {
 
 	public ColumnHeaderClickEventMatcher(final int stateMask, final int button) {
-		super(stateMask, GridRegion.COLUMN_HEADER, button);
+		super(stateMask, GridLabels.COLUMN_HEADER, button);
 	}
 
 	@Override
@@ -40,7 +40,7 @@ public class ColumnHeaderClickEventMatcher extends MouseEventMatcher {
 	    return super.matches(natTable, event, regionLabels) && isNearTheHeaderEdge(natTable, event) && isNotFilterRegion(regionLabels);
 	}
 
-	private boolean isNearTheHeaderEdge(final ILayer natLayer, final MouseEvent event) {
+	private boolean isNearTheHeaderEdge(final Layer natLayer, final MouseEvent event) {
 		final CellEdgeEnum cellEdge= CellEdgeDetectUtil.getHorizontalCellEdge(
                                                            natLayer, 
                                                            new LPoint(event.x, event.y), 
@@ -50,7 +50,7 @@ public class ColumnHeaderClickEventMatcher extends MouseEventMatcher {
 
     private boolean isNotFilterRegion(final LabelStack regionLabels) {
         if (regionLabels != null) {
-            return !regionLabels.getLabels().contains(GridRegion.FILTER_ROW);
+            return !regionLabels.getLabels().contains(GridLabels.FILTER_ROW);
         }
         return true;
     }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortStatePersistor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/SortStatePersistor.java
index 677f0eb2..61722caa 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortStatePersistor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/SortStatePersistor.java
@@ -17,28 +17,30 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
-import java.util.Properties;
+import java.util.Map;
 
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.sort.core.SortDirection;
+import org.eclipse.statet.ecommons.waltable.sort.core.SortModel;
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
 /**
  * Handles persisting of the sorting state.
- * The sorting state is read from and restored to the {@link ISortModel}.
+ * The sorting state is read from and restored to the {@link SortModel}.
  * 
  * @param <T> Type of the Beans in the backing data source.
  */
-public class SortStatePersistor<T> implements IPersistable {
+public class SortStatePersistor<T> implements Persistable {
 	
 	
 	public static final String PERSISTENCE_KEY_SORTING_STATE= ".SortHeaderLayer.sortingState"; //$NON-NLS-1$
-	private final ISortModel sortModel;
+	private final SortModel sortModel;
 
-	public SortStatePersistor(final ISortModel sortModel) {
+	public SortStatePersistor(final SortModel sortModel) {
 		this.sortModel= sortModel;
 	}
 
@@ -52,7 +54,7 @@ public class SortStatePersistor<T> implements IPersistable {
 	 * 	column index : sort direction : sort order |
 	 */
 	@Override
-	public void saveState(final String prefix, final Properties properties) {
+	public void saveState(final String prefix, final Map<String, String> properties) {
 		final StringBuilder buffer= new StringBuilder();
 		
 		for (final long id : this.sortModel.getSortedColumnIds()) {
@@ -73,10 +75,10 @@ public class SortStatePersistor<T> implements IPersistable {
 	}
 
 	/**
-	 * Parses the saved string and restores the state to the {@link ISortModel}.
+	 * Parses the saved string and restores the state to the {@link SortModel}.
 	 */
 	@Override
-	public void loadState(final String prefix, final Properties properties) {
+	public void loadState(final String prefix, final Map<String, String> properties) {
 		
 		/*
 		 * restoring the sortState starts with a clean sortModel. This step
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/config/DefaultSortConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/config/DefaultSortConfiguration.java
index 25a53c16..31a14aa5 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/config/DefaultSortConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/config/DefaultSortConfiguration.java
@@ -16,17 +16,15 @@ package org.eclipse.statet.ecommons.waltable.sort.config;
 import org.eclipse.swt.SWT;
 
 import org.eclipse.statet.ecommons.waltable.config.CellConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.config.DefaultComparator;
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
 import org.eclipse.statet.ecommons.waltable.config.IConfiguration;
-import org.eclipse.statet.ecommons.waltable.grid.GridRegion;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.config.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
+import org.eclipse.statet.ecommons.waltable.grid.core.GridLabels;
 import org.eclipse.statet.ecommons.waltable.painter.cell.decorator.BeveledBorderDecorator;
-import org.eclipse.statet.ecommons.waltable.sort.SortConfigAttributes;
-import org.eclipse.statet.ecommons.waltable.sort.action.SortColumnAction;
-import org.eclipse.statet.ecommons.waltable.sort.painter.SortableHeaderTextPainter;
-import org.eclipse.statet.ecommons.waltable.style.DisplayMode;
+import org.eclipse.statet.ecommons.waltable.sort.swt.SortableHeaderTextPainter;
+import org.eclipse.statet.ecommons.waltable.sort.ui.action.SortColumnAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.MouseEventMatcher;
 
@@ -39,34 +37,32 @@ public class DefaultSortConfiguration implements IConfiguration {
 	/** The sort sequence can be appended to this base */
 	public static final String SORT_SEQ_CONFIG_TYPE= "SORT_SEQ_"; //$NON-NLS-1$
 	
-	private final ICellPainter cellPainter;
+	private final LayerCellPainter layerCellPainter;
 	
 	public DefaultSortConfiguration() {
 		this(new BeveledBorderDecorator(new SortableHeaderTextPainter()));
 	}
 	
-	public DefaultSortConfiguration(final ICellPainter cellPainter) {
-		this.cellPainter= cellPainter;
+	public DefaultSortConfiguration(final LayerCellPainter layerCellPainter) {
+		this.layerCellPainter= layerCellPainter;
 	}
 	
 	@Override
-	public void configureLayer(final ILayer layer) {}
+	public void configureLayer(final Layer layer) {}
 	
 	@Override
-	public void configureRegistry(final IConfigRegistry configRegistry) {
-		configRegistry.registerConfigAttribute(SortConfigAttributes.SORT_COMPARATOR, new DefaultComparator());
-		
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_PAINTER, this.cellPainter, DisplayMode.NORMAL, SORT_DOWN_CONFIG_TYPE);
-		configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_PAINTER, this.cellPainter, DisplayMode.NORMAL, SORT_UP_CONFIG_TYPE);
+	public void configureRegistry(final ConfigRegistry configRegistry) {
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_PAINTER, this.layerCellPainter, DisplayMode.NORMAL, SORT_DOWN_CONFIG_TYPE);
+		configRegistry.registerAttribute(CellConfigAttributes.CELL_PAINTER, this.layerCellPainter, DisplayMode.NORMAL, SORT_UP_CONFIG_TYPE);
 	}
 	
 	@Override
 	public void configureUiBindings(final UiBindingRegistry uiBindingRegistry) {
 		uiBindingRegistry.registerSingleClickBinding(
-				new MouseEventMatcher(SWT.ALT, GridRegion.COLUMN_HEADER.toString(), 1),	new SortColumnAction(false));
+				new MouseEventMatcher(SWT.ALT, GridLabels.COLUMN_HEADER.toString(), 1),	new SortColumnAction(false));
 		
 		uiBindingRegistry.registerSingleClickBinding(
-				new MouseEventMatcher(SWT.ALT | SWT.MOD2, GridRegion.COLUMN_HEADER.toString(), 1), new SortColumnAction(true));
+				new MouseEventMatcher(SWT.ALT | SWT.MOD2, GridLabels.COLUMN_HEADER.toString(), 1), new SortColumnAction(true));
 	}
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/config/SingleClickSortConfiguration.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/config/SingleClickSortConfiguration.java
index 0b1ead0b..4027bf9c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/config/SingleClickSortConfiguration.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/config/SingleClickSortConfiguration.java
@@ -15,9 +15,9 @@ package org.eclipse.statet.ecommons.waltable.sort.config;
 
 import org.eclipse.swt.SWT;
 
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 import org.eclipse.statet.ecommons.waltable.sort.ColumnHeaderClickEventMatcher;
-import org.eclipse.statet.ecommons.waltable.sort.action.SortColumnAction;
+import org.eclipse.statet.ecommons.waltable.sort.ui.action.SortColumnAction;
 import org.eclipse.statet.ecommons.waltable.ui.binding.UiBindingRegistry;
 import org.eclipse.statet.ecommons.waltable.ui.matcher.MouseEventMatcher;
 
@@ -32,8 +32,8 @@ public class SingleClickSortConfiguration extends DefaultSortConfiguration {
 		super();
 	}
 	
-	public SingleClickSortConfiguration(final ICellPainter cellPainter) {
-		super(cellPainter);
+	public SingleClickSortConfiguration(final LayerCellPainter layerCellPainter) {
+		super(layerCellPainter);
 	}
 	
 	/**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/ClearSortCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/ClearSortCommand.java
index 80a361cd..eb979fcb 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/ClearSortCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/ClearSortCommand.java
@@ -11,11 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.sort;
+package org.eclipse.statet.ecommons.waltable.sort.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
+
+@NonNullByDefault
 public class ClearSortCommand extends AbstractContextFreeCommand {
 	
+	
+	public ClearSortCommand() {
+	}
+	
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/ClearSortCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/ClearSortCommandHandler.java
new file mode 100644
index 00000000..c4acad20
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/ClearSortCommandHandler.java
@@ -0,0 +1,67 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.sort.core;
+
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+
+import java.util.List;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRangeList;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+
+
+@NonNullByDefault
+public class ClearSortCommandHandler implements LayerCommandHandler<ClearSortCommand> {
+	
+	
+	private final SortModel sortModel;
+	
+	
+	public ClearSortCommandHandler(final SortModel sortModel) {
+		this.sortModel= sortModel;
+	}
+	
+	
+	@Override
+	public Class<ClearSortCommand> getCommandClass() {
+		return ClearSortCommand.class;
+	}
+	
+	@Override
+	public boolean doCommand(final Layer targetLayer, final ClearSortCommand command) {
+		final LayerDim layerDim= targetLayer.getDim(HORIZONTAL);
+		
+		final List<Long> sortedIds= this.sortModel.getSortedColumnIds();
+		final LRangeList sortedPositions= new LRangeList();
+		for (final Long id : sortedIds) {
+			final long position= layerDim.getPositionById(id);
+			if (position != LayerDim.POSITION_NA) {
+				sortedPositions.values().add(position);
+			}
+		}
+		
+		this.sortModel.clear();
+		
+		// Fire event
+		final SortColumnEvent sortEvent= new SortColumnEvent(layerDim, sortedPositions);
+		layerDim.getLayer().fireLayerEvent(sortEvent);
+		
+		return true;
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortColumnEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortColumnEvent.java
new file mode 100644
index 00000000..1ac7da37
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortColumnEvent.java
@@ -0,0 +1,47 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.sort.core;
+
+import java.util.List;
+
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.lang.NonNull;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.DimPositionsVisualChangeEvent;
+
+
+@NonNullByDefault
+public class SortColumnEvent extends DimPositionsVisualChangeEvent {
+	
+	
+	public SortColumnEvent(final LayerDim layerDim, final List<LRange> positions) {
+		super(layerDim, positions);
+	}
+	
+	public SortColumnEvent(final LayerDim layerDim, final LRange positions) {
+		super(layerDim, ImCollections.newList(positions));
+	}
+	
+	@Override
+	protected @Nullable DimPositionsVisualChangeEvent toLayer(final LayerDim targetLayerDim,
+			@NonNull final List<@NonNull LRange> positionRanges) {
+		return new SortColumnEvent(targetLayerDim, positionRanges);
+	}
+	
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortDimPositionCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortDimPositionCommand.java
index faa49834..ee5019cf 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortDimPositionCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortDimPositionCommand.java
@@ -11,26 +11,33 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.sort;
+package org.eclipse.statet.ecommons.waltable.sort.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
 
+
+@NonNullByDefault
 public class SortDimPositionCommand extends AbstractDimPositionCommand {
 	
 	
 	private final boolean accumulate;
 	
-	private final SortDirection direction;
+	private final @Nullable SortDirection direction;
 	
 	
-	public SortDimPositionCommand(final ILayerDim layerDim, final long columnPosition,
+	public SortDimPositionCommand(final LayerDim layerDim, final long columnPosition,
 			final boolean accumulate) {
-		this(layerDim, columnPosition, null, accumulate);
+		super(layerDim, columnPosition);
+		
+		this.accumulate= accumulate;
+		this.direction= null;
 	}
 	
-	public SortDimPositionCommand(final ILayerDim layerDim, final long columnPosition,
+	public SortDimPositionCommand(final LayerDim layerDim, final long columnPosition,
 			final SortDirection direction, final boolean accumulate) {
 		super(layerDim, columnPosition);
 		
@@ -60,7 +67,7 @@ public class SortDimPositionCommand extends AbstractDimPositionCommand {
 	 * 
 	 * @return the sort direction or <code>null</code> for automatic iteration
 	 */
-	public SortDirection getDirection() {
+	public @Nullable SortDirection getDirection() {
 		return this.direction;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortDirection.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortDirection.java
index 6e27eb8a..221b3316 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortDirection.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortDirection.java
@@ -11,15 +11,18 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.sort;
+package org.eclipse.statet.ecommons.waltable.sort.core;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+
+@NonNullByDefault
 public enum SortDirection {
 	
 	
 	NONE("Unsorted"), //$NON-NLS-1$
 	ASC("Ascending"), //$NON-NLS-1$
-	DESC("Ascending"); //$NON-NLS-1$
+	DESC("Descending"); //$NON-NLS-1$
 	
 	
 	private final String description;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortHeaderLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortHeaderLayer.java
index 5166882e..d8c225c8 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/SortHeaderLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortHeaderLayer.java
@@ -11,42 +11,50 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.sort;
+package org.eclipse.statet.ecommons.waltable.sort.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
-import org.eclipse.statet.ecommons.waltable.layer.ForwardLayer;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.LabelStack;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ForwardLayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCellDim;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.ForwardLayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LabelStack;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellDim;
+import org.eclipse.statet.ecommons.waltable.sort.SortStatePersistor;
 import org.eclipse.statet.ecommons.waltable.sort.config.DefaultSortConfiguration;
 
 
 /**
- * Enables sorting of the data. Uses an {@link ISortModel} to do/track the sorting.
+ * Enables sorting of the data. Uses an {@link SortModel} to do/track the sorting.
  * @param <T> Type of the Beans in the backing data source.
  * 
  * @see DefaultSortConfiguration
  * @see SortStatePersistor
  */
-public class SortHeaderLayer<T> extends ForwardLayer implements IPersistable {
+@NonNullByDefault
+public class SortHeaderLayer<T> extends ForwardLayer<ForwardLayerDim<? extends SortHeaderLayer<T>>> implements Persistable {
 	
 	
 	/** Handles the actual sorting of underlying data */
-	private final ISortModel sortModel;
+	private final SortModel sortModel;
 	
 	
-	public SortHeaderLayer(final ILayer underlyingLayer, final ISortModel sortModel) {
+	public SortHeaderLayer(final Layer underlyingLayer, final SortModel sortModel) {
 		this(underlyingLayer, sortModel, true);
 	}
 	
-	public SortHeaderLayer(final ILayer underlyingLayer, final ISortModel sortModel, final boolean useDefaultConfiguration) {
+	public SortHeaderLayer(final Layer underlyingLayer, final SortModel sortModel, final boolean useDefaultConfiguration) {
 		super(underlyingLayer);
 		this.sortModel= sortModel;
 		
+		init();
+		
 		registerPersistable(new SortStatePersistor<T>(sortModel));
 		
 		if (useDefaultConfiguration) {
@@ -54,23 +62,28 @@ public class SortHeaderLayer<T> extends ForwardLayer implements IPersistable {
 		}
 	}
 	
+	@Override
+	protected ForwardLayerDim<? extends SortHeaderLayer<T>> createDim(final Orientation orientation) {
+		return new ForwardLayerDim<>(this, getUnderlyingLayer().getDim(orientation));
+	}
+	
 	
 	/**
 	 * @return The ISortModel that is used to handle the sorting of the underlying data.
 	 */
-	public ISortModel getSortModel() {
+	public SortModel getSortModel() {
 		return this.sortModel;
 	}
 	
 	
 	@Override
-	protected ILayerCell createCell(final ILayerCellDim hDim, final ILayerCellDim vDim,
-			final ILayerCell underlyingCell) {
+	protected LayerCell createCell(final LayerCellDim hDim, final LayerCellDim vDim,
+			final LayerCell underlyingCell) {
 		return new ForwardLayerCell(this, hDim, vDim, underlyingCell) {
 			
 			@Override
-			public LabelStack getConfigLabels() {
-				final LabelStack configLabels= super.getConfigLabels();
+			public LabelStack getLabels() {
+				final LabelStack configLabels= super.getLabels();
 				
 				final long id= getDim(HORIZONTAL).getId();
 				if (SortHeaderLayer.this.sortModel.isSorted(id)) {
@@ -85,6 +98,8 @@ public class SortHeaderLayer<T> extends ForwardLayer implements IPersistable {
 					case DESC:
 						configLabels.addLabelOnTop(DefaultSortConfiguration.SORT_DOWN_CONFIG_TYPE);
 						break;
+					default:
+						break;
 					}
 				}
 				
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/ISortModel.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortModel.java
index 160e0662..deabdc74 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/ISortModel.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortModel.java
@@ -11,31 +11,35 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.sort;
+package org.eclipse.statet.ecommons.waltable.sort.core;
 
 import java.util.List;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
 
 /**
  * Interface providing sorting functionality.
  */
-public interface ISortModel {
+@NonNullByDefault
+public interface SortModel {
+	
 	
 	/**
 	 * @return List of column ids that are sorted.
 	 */
-	public List<Long> getSortedColumnIds();
+	List<Long> getSortedColumnIds();
 	
 	/**
 	 * @return TRUE if the column with the given id is sorted at the moment.
 	 */
-	public boolean isSorted(long columnId);
+	boolean isSorted(long columnId);
 	
 	/**
 	 * @return the direction in which the column with the given id is
 	 * currently sorted
 	 */
-	public SortDirection getSortDirection(long columnId);
+	SortDirection getSortDirection(long columnId);
 	
 	/**
 	 * @return when multiple columns are sorted, this returns the order of the
@@ -44,7 +48,7 @@ public interface ISortModel {
 	 * Example: If column ids 3, 6, 9 are sorted (in that order) the sort order
 	 * for id 6 is 1.
 	 */
-	public int getSortOrder(long columnId);
+	int getSortOrder(long columnId);
 	
 	/**
 	 * This method is called by the {@link SortCommandHandler} in response to a sort command.
@@ -52,11 +56,11 @@ public interface ISortModel {
 	 *
 	 * @param accumulate flag indicating if the column should added to a previous sort.
 	 */
-	public void sort(long columnId, SortDirection sortDirection, boolean accumulate);
+	void sort(long columnId, SortDirection sortDirection, boolean accumulate);
 	
 	/**
 	 * Remove all sorting
 	 */
-	public void clear();
+	void clear();
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortPositionCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortPositionCommandHandler.java
new file mode 100644
index 00000000..3ce0deeb
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/core/SortPositionCommandHandler.java
@@ -0,0 +1,62 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.sort.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+
+
+/**
+ * Handle sort commands
+ */
+@NonNullByDefault
+public class SortPositionCommandHandler extends AbstractLayerCommandHandler<SortDimPositionCommand> {
+	
+	
+	private final SortModel sortModel;
+	
+	
+	public SortPositionCommandHandler(final SortModel sortModel) {
+		this.sortModel= sortModel;
+	}
+	
+	
+	@Override
+	public Class<SortDimPositionCommand> getCommandClass() {
+		return SortDimPositionCommand.class;
+	}
+	
+	@Override
+	protected boolean doCommand(final SortDimPositionCommand command) {
+		final LayerDim layerDim= command.getDim();
+		final long columnId= layerDim.getPositionId(command.getPosition(), command.getPosition());
+		
+		SortDirection newSortDirection= command.getDirection();
+		if (newSortDirection == null) {
+			newSortDirection= this.sortModel.getSortDirection(columnId).getNextSortDirection();
+		}
+		this.sortModel.sort(columnId, newSortDirection, command.isAccumulate());
+		
+		// Fire event
+		final SortColumnEvent sortEvent= new SortColumnEvent(layerDim,
+				new LRange(command.getPosition()) );
+		layerDim.getLayer().fireLayerEvent(sortEvent);
+		
+		return true;
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/painter/SortableHeaderTextPainter.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/swt/SortableHeaderTextPainter.java
index eddbc08d..09801f5a 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/painter/SortableHeaderTextPainter.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/swt/SortableHeaderTextPainter.java
@@ -11,14 +11,16 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.sort.painter;
+package org.eclipse.statet.ecommons.waltable.sort.swt;
 
 import org.eclipse.swt.graphics.Image;
 
-import org.eclipse.statet.ecommons.waltable.config.IConfigRegistry;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.config.ConfigRegistry;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.CellPainterWrapper;
-import org.eclipse.statet.ecommons.waltable.painter.cell.ICellPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.ImagePainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.TextPainter;
 import org.eclipse.statet.ecommons.waltable.painter.cell.decorator.CellPainterDecorator;
@@ -27,97 +29,99 @@ import org.eclipse.statet.ecommons.waltable.ui.util.CellEdgeEnum;
 import org.eclipse.statet.ecommons.waltable.util.GUIHelper;
 
 
+@NonNullByDefault
 public class SortableHeaderTextPainter extends CellPainterWrapper {
-
+	
+	
 	/**
 	 * Creates the default {@link SortableHeaderTextPainter} that uses a {@link TextPainter}
-	 * as base {@link ICellPainter} and decorate it with the {@link SortIconPainter} on the right
+	 * as base {@link LayerCellPainter} and decorate it with the {@link SortIconPainter} on the right
 	 * edge of the cell.
 	 */
 	public SortableHeaderTextPainter() {
 		this(new TextPainter());
 	}
-
+	
 	/**
-	 * Creates a {@link SortableHeaderTextPainter} that uses the given {@link ICellPainter}
-	 * as base {@link ICellPainter} and decorate it with the {@link SortIconPainter} on the right
+	 * Creates a {@link SortableHeaderTextPainter} that uses the given {@link LayerCellPainter}
+	 * as base {@link LayerCellPainter} and decorate it with the {@link SortIconPainter} on the right
 	 * edge of the cell.
-	 * @param interiorPainter the base {@link ICellPainter} to use
+	 * @param interiorPainter the base {@link LayerCellPainter} to use
 	 */
-	public SortableHeaderTextPainter(final ICellPainter interiorPainter) {
+	public SortableHeaderTextPainter(final LayerCellPainter interiorPainter) {
 		this(interiorPainter, CellEdgeEnum.RIGHT);
 	}
-
+	
 	/**
-	 * Creates a {@link SortableHeaderTextPainter} that uses the given {@link ICellPainter}
-	 * as base {@link ICellPainter} and decorate it with the {@link SortIconPainter} on the specified
+	 * Creates a {@link SortableHeaderTextPainter} that uses the given {@link LayerCellPainter}
+	 * as base {@link LayerCellPainter} and decorate it with the {@link SortIconPainter} on the specified
 	 * edge of the cell.
-	 * @param interiorPainter the base {@link ICellPainter} to use
+	 * @param interiorPainter the base {@link LayerCellPainter} to use
 	 * @param cellEdge the edge of the cell on which the sort indicator decoration should be applied
 	 */
-	public SortableHeaderTextPainter(final ICellPainter interiorPainter, final CellEdgeEnum cellEdge) {
+	public SortableHeaderTextPainter(final LayerCellPainter interiorPainter, final CellEdgeEnum cellEdge) {
 		this(interiorPainter, cellEdge, new SortIconPainter(true));
 	}
-
+	
 	/**
-	 * Creates a {@link SortableHeaderTextPainter} that uses the given {@link ICellPainter}
-	 * as base {@link ICellPainter} and decorate it with the given {@link ICellPainter} to use for sort
+	 * Creates a {@link SortableHeaderTextPainter} that uses the given {@link LayerCellPainter}
+	 * as base {@link LayerCellPainter} and decorate it with the given {@link LayerCellPainter} to use for sort
 	 * related decoration on the specified edge of the cell.
-	 * @param interiorPainter the base {@link ICellPainter} to use
+	 * @param interiorPainter the base {@link LayerCellPainter} to use
 	 * @param cellEdge the edge of the cell on which the sort indicator decoration should be applied
-	 * @param decoratorPainter the {@link ICellPainter} that should be used to paint the sort related
+	 * @param decoratorPainter the {@link LayerCellPainter} that should be used to paint the sort related
 	 * 			decoration (by default the {@link SortIconPainter} will be used)
 	 */
-	public SortableHeaderTextPainter(final ICellPainter interiorPainter, final CellEdgeEnum cellEdge, final ICellPainter decoratorPainter) {
+	public SortableHeaderTextPainter(final LayerCellPainter interiorPainter, final CellEdgeEnum cellEdge, final LayerCellPainter decoratorPainter) {
 		setWrappedPainter(new CellPainterDecorator(interiorPainter, cellEdge, decoratorPainter));
 	}
-
+	
 	//the following constructors are intended to configure the CellPainterDecorator that is created as
 	//the wrapped painter of this SortableHeaderTextPainter
-
-    /**
-     * Creates a {@link SortableHeaderTextPainter} that uses the given {@link ICellPainter} as base
-	 * {@link ICellPainter}. It will use the {@link SortIconPainter} as decorator for sort related 
+	
+	/**
+	 * Creates a {@link SortableHeaderTextPainter} that uses the given {@link LayerCellPainter} as base
+	 * {@link LayerCellPainter}. It will use the {@link SortIconPainter} as decorator for sort related 
 	 * decorations at the specified cell edge, which can be configured to render the background or 
 	 * not via method parameter. With the additional parameters, the behaviour of the created 
 	 * {@link CellPainterDecorator} can be configured in terms of rendering.
-	 * @param interiorPainter the base {@link ICellPainter} to use
+	 * @param interiorPainter the base {@link LayerCellPainter} to use
 	 * @param cellEdge the edge of the cell on which the sort indicator decoration should be applied
 	 * @param paintBg flag to configure whether the {@link SortIconPainter} should paint the background or not
-     * @param spacing the number of pixels that should be used as spacing between cell edge and decoration
-     * @param paintDecorationDependent flag to configure if the base {@link ICellPainter} should render
-     * 			decoration dependent or not. If it is set to <code>false</code>, the base painter will
-     * 			always paint at the same coordinates, using the whole cell bounds, <code>true</code>
-     * 			will cause the bounds of the cell to shrink for the base painter.
-     */
-    public SortableHeaderTextPainter(final ICellPainter interiorPainter, final CellEdgeEnum cellEdge,
-    		final boolean paintBg, final long spacing, final boolean paintDecorationDependent) {
-    	
-	    final ICellPainter sortPainter= new SortIconPainter(paintBg);
-	    final CellPainterDecorator painter= new CellPainterDecorator(interiorPainter, cellEdge, 
-	    		spacing, sortPainter, paintDecorationDependent);
-        setWrappedPainter(painter);
-    }
+	 * @param spacing the number of pixels that should be used as spacing between cell edge and decoration
+	 * @param paintDecorationDependent flag to configure if the base {@link LayerCellPainter} should render
+	 *     decoration dependent or not. If it is set to <code>false</code>, the base painter will
+	 *     always paint at the same coordinates, using the whole cell bounds, <code>true</code>
+	 *     will cause the bounds of the cell to shrink for the base painter.
+	 */
+	public SortableHeaderTextPainter(final LayerCellPainter interiorPainter, final CellEdgeEnum cellEdge,
+			final boolean paintBg, final long spacing, final boolean paintDecorationDependent) {
+		final LayerCellPainter sortPainter= new SortIconPainter(paintBg);
+		final CellPainterDecorator painter= new CellPainterDecorator(interiorPainter, cellEdge, 
+				spacing, sortPainter, paintDecorationDependent);
+		setWrappedPainter(painter);
+	}
 	
 	/**
-	 * Creates a {@link SortableHeaderTextPainter} that uses the given {@link ICellPainter} as base
-	 * {@link ICellPainter} and decorate it with the {@link SortIconPainter} on the right
+	 * Creates a {@link SortableHeaderTextPainter} that uses the given {@link LayerCellPainter} as base
+	 * {@link LayerCellPainter} and decorate it with the {@link SortIconPainter} on the right
 	 * edge of the cell. This constructor gives the opportunity to configure the behaviour of the
 	 * {@link SortIconPainter} and the {@link CellPainterDecorator} for some attributes.
 	 * Remains because of downwards compatibility.
-	 * @param interiorPainter the base {@link ICellPainter} to use
+	 * @param interiorPainter the base {@link LayerCellPainter} to use
 	 * @param paintBg flag to configure whether the {@link SortIconPainter} should paint the background or not
-	 * @param interiorPainterToSpanFullWidth flag to configure how the bounds of the base painter should be
-	 * 			calculated 
+	 * @param interiorPainterToSpanFullWidth flag to configure how the bounds of the base painter
+	 *     should be calculated 
 	 */
-    public SortableHeaderTextPainter(final ICellPainter interiorPainter, final boolean paintBg, final boolean interiorPainterToSpanFullWidth) {
-	    final ICellPainter sortPainter= new SortIconPainter(paintBg);
-	    final CellPainterDecorator painter= new CellPainterDecorator(interiorPainter, CellEdgeEnum.RIGHT, 0, sortPainter);
-	    painter.setPaintDecorationDependent(!interiorPainterToSpanFullWidth);
-        setWrappedPainter(painter);
+	public SortableHeaderTextPainter(final LayerCellPainter interiorPainter, final boolean paintBg,
+			final boolean interiorPainterToSpanFullWidth) {
+		final LayerCellPainter sortPainter= new SortIconPainter(paintBg);
+		final CellPainterDecorator painter= new CellPainterDecorator(interiorPainter, CellEdgeEnum.RIGHT, 0, sortPainter);
+		painter.setPaintDecorationDependent(!interiorPainterToSpanFullWidth);
+		setWrappedPainter(painter);
 	}
-    
-    
+	
+	
 	/**
 	 * Paints the triangular sort icon images.
 	 */
@@ -130,7 +134,7 @@ public class SortableHeaderTextPainter extends CellPainterWrapper {
 		
 		
 		@Override
-		protected Image getImage(final ILayerCell cell, final IConfigRegistry configRegistry) {
+		protected Image getImage(final LayerCell cell, final ConfigRegistry configRegistry) {
 			Image icon= null;
 			
 			if (isSortedAscending(cell)) {
@@ -142,16 +146,16 @@ public class SortableHeaderTextPainter extends CellPainterWrapper {
 			return icon;
 		}
 		
-		private boolean isSortedAscending(final ILayerCell cell) {
-			return cell.getConfigLabels().hasLabel(DefaultSortConfiguration.SORT_UP_CONFIG_TYPE);
+		private boolean isSortedAscending(final LayerCell cell) {
+			return cell.getLabels().hasLabel(DefaultSortConfiguration.SORT_UP_CONFIG_TYPE);
 		}
 		
-		private boolean isSortedDescending(final ILayerCell cell) {
-			return cell.getConfigLabels().hasLabel(DefaultSortConfiguration.SORT_DOWN_CONFIG_TYPE);
+		private boolean isSortedDescending(final LayerCell cell) {
+			return cell.getLabels().hasLabel(DefaultSortConfiguration.SORT_DOWN_CONFIG_TYPE);
 		}
 		
-		private int getSortSequence(final ILayerCell cell) {
-			for (final String configLabel : cell.getConfigLabels().getLabels()) {
+		private int getSortSequence(final LayerCell cell) {
+			for (final String configLabel : cell.getLabels().getLabels()) {
 				if (configLabel.startsWith(DefaultSortConfiguration.SORT_SEQ_CONFIG_TYPE)) {
 					return Integer.parseInt(configLabel.substring(
 							DefaultSortConfiguration.SORT_SEQ_CONFIG_TYPE.length() ));
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/action/SortColumnAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/ui/action/SortColumnAction.java
index 0932a89f..647921fc 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/sort/action/SortColumnAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/sort/ui/action/SortColumnAction.java
@@ -11,14 +11,14 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.sort.action;
+package org.eclipse.statet.ecommons.waltable.sort.ui.action;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
 
 import org.eclipse.swt.events.MouseEvent;
 
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.sort.SortDimPositionCommand;
+import org.eclipse.statet.ecommons.waltable.sort.core.SortDimPositionCommand;
 import org.eclipse.statet.ecommons.waltable.ui.NatEventData;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
 
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/AutomaticSpanningDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/AutomaticSpanningDataProvider.java
index d8762e40..a72381f9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/AutomaticSpanningDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/AutomaticSpanningDataProvider.java
@@ -11,19 +11,24 @@
  #     Dirk Fauth <dirk.fauth@gmail.com> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.data;
+package org.eclipse.statet.ecommons.waltable.util.data;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 import java.util.Objects;
-import java.util.Properties;
 import java.util.StringTokenizer;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.layer.cell.DataCell;
-import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.Persistable;
+import org.eclipse.statet.ecommons.waltable.core.data.DataCell;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
+import org.eclipse.statet.ecommons.waltable.core.data.SpanningDataProvider;
 
 
 /**
@@ -45,7 +50,8 @@ import org.eclipse.statet.ecommons.waltable.persistence.IPersistable;
  * by building the spanning cell for the matching rectangle. As this would be quite time consuming
  * calculations, this is not supported out of the box by NatTable.
  */
-public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPersistable {
+@NonNullByDefault
+public class AutomaticSpanningDataProvider implements SpanningDataProvider, Persistable {
 	
 	
 	public static final String PERSISTENCE_KEY_AUTO_COLUMN_SPAN= ".autoColumnSpan"; //$NON-NLS-1$
@@ -57,7 +63,7 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 	/**
 	 * The IDataProvider that is wrapped by this AutomaticSpanningDataProvider
 	 */
-	private final IDataProvider underlyingDataProvider;
+	private final DataProvider underlyingDataProvider;
 	
 	/**
 	 * Flag to configure this AutomaticSpanningDataProvider to perform automatic column spanning
@@ -93,7 +99,7 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 	 * @param autoRowSpan Flag to configure this AutomaticSpanningDataProvider to perform 
 	 * 			automatic row spanning
 	 */
-	public AutomaticSpanningDataProvider(final IDataProvider underlyingDataProvider,
+	public AutomaticSpanningDataProvider(final DataProvider underlyingDataProvider,
 			final boolean autoColumnSpan, final boolean autoRowSpan) {
 		this.underlyingDataProvider= underlyingDataProvider;
 		this.autoColumnSpan= autoColumnSpan;
@@ -101,12 +107,14 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 	}
 	
 	@Override
-	public Object getDataValue(final long columnIndex, final long rowIndex, final int flags, final IProgressMonitor monitor) {
+	public @Nullable Object getDataValue(final long columnIndex, final long rowIndex,
+			final int flags, final @Nullable IProgressMonitor monitor) {
 		return this.underlyingDataProvider.getDataValue(columnIndex, rowIndex, flags, monitor);
 	}
 	
 	@Override
-	public void setDataValue(final long columnIndex, final long rowIndex, final Object newValue) {
+	public void setDataValue(final long columnIndex, final long rowIndex,
+			final @Nullable Object newValue) {
 		this.underlyingDataProvider.setDataValue(columnIndex, rowIndex, newValue);
 	}
 	
@@ -135,6 +143,7 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 		return new DataCell(cellColumnPosition, cellRowPosition, columnSpan, rowSpan);
 	}
 	
+	
 	/**
 	 * Check if the given column should be used for auto spanning.
 	 * @param columnPosition The column position to check for auto spanning
@@ -144,7 +153,7 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 	protected boolean isAutoSpanEnabledForColumn(final long columnPosition, final long rowPosition) {
 		return (this.autoColumnSpan && isAutoSpanRow(rowPosition));
 	}
-
+	
 	/**
 	 * Check if the given row should be used for auto spanning.
 	 * @param columnPosition The column position for which the row spanning should be checked.
@@ -180,8 +189,8 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 	 * won't be auto spanned anymore.
 	 * @param columnPositions The column positions to add for auto spanning.
 	 */
-	public void addAutoSpanningColumnPositions(final Long... columnPositions) {
-		this.autoSpanColumns.addAll(Arrays.asList(columnPositions));
+	public void addAutoSpanningColumnPositions(final ImList<Long> columnPositions) {
+		this.autoSpanColumns.addAll(columnPositions);
 	}
 	
 	/**
@@ -191,24 +200,24 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 	 * be auto spanned anymore.
 	 * @param rowPositions The row positions to add for auto spanning.
 	 */
-	public void addAutoSpanningRowPositions(final Long... rowPositions) {
-		this.autoSpanRows.addAll(Arrays.asList(rowPositions));
+	public void addAutoSpanningRowPositions(final ImList<Long> rowPositions) {
+		this.autoSpanRows.addAll(rowPositions);
 	}
 	
 	/**
 	 * Removes the given column positions for auto spanning. 
 	 * @param columnPositions The column positions to remove for auto spanning.
 	 */
-	public void removeAutoSpanningColumnPositions(final Long... columnPositions) {
-		this.autoSpanColumns.removeAll(Arrays.asList(columnPositions));
+	public void removeAutoSpanningColumnPositions(final ImList<Long> columnPositions) {
+		this.autoSpanColumns.removeAll(columnPositions);
 	}
 	
 	/**
 	 * Removes the given row positions for auto spanning. 
 	 * @param rowPositions The row positions to remove for auto spanning.
 	 */
-	public void removeAutoSpanningRowPositions(final Long... rowPositions) {
-		this.autoSpanRows.removeAll(Arrays.asList(rowPositions));
+	public void removeAutoSpanningRowPositions(final ImList<Long> rowPositions) {
+		this.autoSpanRows.removeAll(rowPositions);
 	}
 	
 	/**
@@ -236,7 +245,7 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 	 * @param columnPosition The column position whose spanning starting column is searched
 	 * @param rowPosition The row position where the column spanning should be performed.
 	 * @return The column position where the spanning starts or the given column position
-	 * 			if it is not spanned with the columns to the left.
+	 *     if it is not spanned with the columns to the left.
 	 */
 	protected long getStartColumnPosition(final long columnPosition, final long rowPosition) {
 		if (columnPosition <= 0 || !isAutoSpanColumn(columnPosition) || !isAutoSpanColumn(columnPosition-1)) {
@@ -357,47 +366,48 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 		this.autoRowSpan= autoRowSpan;
 	}
 	
+	
 	@Override
-	public void saveState(final String prefix, final Properties properties) {
-		properties.setProperty(prefix + PERSISTENCE_KEY_AUTO_COLUMN_SPAN, Boolean.valueOf(this.autoColumnSpan).toString());
-		properties.setProperty(prefix + PERSISTENCE_KEY_AUTO_ROW_SPAN, Boolean.valueOf(this.autoRowSpan).toString());
+	public void saveState(final String prefix, final Map<String, String> properties) {
+		properties.put(prefix + PERSISTENCE_KEY_AUTO_COLUMN_SPAN, Boolean.toString(this.autoColumnSpan));
+		properties.put(prefix + PERSISTENCE_KEY_AUTO_ROW_SPAN, Boolean.toString(this.autoRowSpan));
 		
 		if (this.autoSpanColumns.size() > 0) {
 			final StringBuilder strBuilder= new StringBuilder();
 			for (final Long index : this.autoSpanColumns) {
 				strBuilder.append(index);
-				strBuilder.append(IPersistable.VALUE_SEPARATOR);
+				strBuilder.append(Persistable.VALUE_SEPARATOR);
 			}
-			properties.setProperty(prefix + PERSISTENCE_KEY_AUTO_SPAN_COLUMNS, strBuilder.toString());
+			properties.put(prefix + PERSISTENCE_KEY_AUTO_SPAN_COLUMNS, strBuilder.toString());
 		}
 		
 		if (this.autoSpanRows.size() > 0) {
 			final StringBuilder strBuilder= new StringBuilder();
 			for (final Long index : this.autoSpanRows) {
 				strBuilder.append(index);
-				strBuilder.append(IPersistable.VALUE_SEPARATOR);
+				strBuilder.append(Persistable.VALUE_SEPARATOR);
 			}
-			properties.setProperty(prefix + PERSISTENCE_KEY_AUTO_SPAN_ROWS, strBuilder.toString());
+			properties.put(prefix + PERSISTENCE_KEY_AUTO_SPAN_ROWS, strBuilder.toString());
 		}
 	}
 	
 	@Override
-	public void loadState(final String prefix, final Properties properties) {
-		String property= properties.getProperty(prefix + PERSISTENCE_KEY_AUTO_COLUMN_SPAN);
+	public void loadState(final String prefix, final Map<String, String> properties) {
+		String property= properties.get(prefix + PERSISTENCE_KEY_AUTO_COLUMN_SPAN);
 		if (property != null) {
-			this.autoColumnSpan= Boolean.valueOf(property);
+			this.autoColumnSpan= Boolean.parseBoolean(property);
 		}
 		
-		property= properties.getProperty(prefix + PERSISTENCE_KEY_AUTO_ROW_SPAN);
+		property= properties.get(prefix + PERSISTENCE_KEY_AUTO_ROW_SPAN);
 		if (property != null) {
-			this.autoRowSpan= Boolean.valueOf(property);
+			this.autoRowSpan= Boolean.parseBoolean(property);
 		}
 		
 		this.autoSpanColumns.clear();
-		property= properties.getProperty(prefix + PERSISTENCE_KEY_AUTO_SPAN_COLUMNS);
+		property= properties.get(prefix + PERSISTENCE_KEY_AUTO_SPAN_COLUMNS);
 		if (property != null) {
 			final List<Long> newAutoSpanColumns= new ArrayList<>();
-			final StringTokenizer tok= new StringTokenizer(property, IPersistable.VALUE_SEPARATOR);
+			final StringTokenizer tok= new StringTokenizer(property, Persistable.VALUE_SEPARATOR);
 			while (tok.hasMoreTokens()) {
 				final String index= tok.nextToken();
 				newAutoSpanColumns.add(Long.valueOf(index));
@@ -407,10 +417,10 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 		}
 		
 		this.autoSpanRows.clear();
-		property= properties.getProperty(prefix + PERSISTENCE_KEY_AUTO_SPAN_ROWS);
+		property= properties.get(prefix + PERSISTENCE_KEY_AUTO_SPAN_ROWS);
 		if (property != null) {
 			final List<Long> newAutoSpanRows= new ArrayList<>();
-			final StringTokenizer tok= new StringTokenizer(property, IPersistable.VALUE_SEPARATOR);
+			final StringTokenizer tok= new StringTokenizer(property, Persistable.VALUE_SEPARATOR);
 			while (tok.hasMoreTokens()) {
 				final String index= tok.nextToken();
 				newAutoSpanRows.add(Long.valueOf(index));
@@ -419,4 +429,5 @@ public class AutomaticSpanningDataProvider implements ISpanningDataProvider, IPe
 			this.autoSpanRows.addAll(newAutoSpanRows);
 		}
 	}
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DummyBodyDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/DummyBodyDataProvider.java
index 5ddd0c6d..f3743ecd 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DummyBodyDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/DummyBodyDataProvider.java
@@ -11,18 +11,18 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.data;
+package org.eclipse.statet.ecommons.waltable.util.data;
 
 import java.util.HashMap;
 import java.util.Map;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LPoint;
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LPoint;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
 
 
-public class DummyBodyDataProvider implements IDataProvider {
+public class DummyBodyDataProvider implements DataProvider {
 	
 	
 	private final long columnCount;
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DummyColumnHeaderDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/DummyColumnHeaderDataProvider.java
index 414cec3a..5d9d0524 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DummyColumnHeaderDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/DummyColumnHeaderDataProvider.java
@@ -11,20 +11,20 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.data;
+package org.eclipse.statet.ecommons.waltable.util.data;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
 
 
-public class DummyColumnHeaderDataProvider implements IDataProvider {
+public class DummyColumnHeaderDataProvider implements DataProvider {
 	
 	
-	private final IDataProvider bodyDataProvider;
+	private final DataProvider bodyDataProvider;
 	
 	
-	public DummyColumnHeaderDataProvider(final IDataProvider bodyDataProvider) {
+	public DummyColumnHeaderDataProvider(final DataProvider bodyDataProvider) {
 		this.bodyDataProvider= bodyDataProvider;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DummySpanningBodyDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/DummySpanningBodyDataProvider.java
index 27fa3177..b9b16c15 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DummySpanningBodyDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/DummySpanningBodyDataProvider.java
@@ -11,18 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.data;
+package org.eclipse.statet.ecommons.waltable.util.data;
 
-import org.eclipse.statet.ecommons.waltable.data.ISpanningDataProvider;
-import org.eclipse.statet.ecommons.waltable.layer.cell.DataCell;
+import org.eclipse.statet.ecommons.waltable.core.data.DataCell;
+import org.eclipse.statet.ecommons.waltable.core.data.SpanningDataProvider;
 
 
-public class DummySpanningBodyDataProvider extends DummyBodyDataProvider implements ISpanningDataProvider {
+public class DummySpanningBodyDataProvider extends DummyBodyDataProvider implements SpanningDataProvider {
 	
 	private static final long BLOCK_SIZE= 4;
-
+	
 	private static final long CELL_SPAN= 2;
 	
+	
 	public DummySpanningBodyDataProvider(final long columnCount, final long rowCount) {
 		super(columnCount, rowCount);
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IColumnPropertyAccessor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/PropertyColumnAccessor.java
index 094364fb..6a83c480 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IColumnPropertyAccessor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/PropertyColumnAccessor.java
@@ -11,9 +11,11 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.data;
+package org.eclipse.statet.ecommons.waltable.util.data;
 
+import org.eclipse.statet.ecommons.waltable.core.data.ColumnAccessor;
 
-public interface IColumnPropertyAccessor<T> extends IColumnAccessor<T>, IColumnPropertyResolver {
+
+public interface PropertyColumnAccessor<T> extends ColumnAccessor<T>, PropertyColumnResolver {
 
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DefaultColumnHeaderDataProvider.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/PropertyColumnHeaderDataProvider.java
index f38d5727..823fc5aa 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/grid/data/DefaultColumnHeaderDataProvider.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/PropertyColumnHeaderDataProvider.java
@@ -11,50 +11,40 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.grid.data;
+package org.eclipse.statet.ecommons.waltable.util.data;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
 
 import java.util.Map;
 
 import org.eclipse.core.runtime.IProgressMonitor;
 
-import org.eclipse.statet.ecommons.waltable.data.IDataProvider;
+import org.eclipse.statet.jcommons.collections.ImList;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.data.DataProvider;
 
-public class DefaultColumnHeaderDataProvider implements IDataProvider {
-	
+
+@NonNullByDefault
+public class PropertyColumnHeaderDataProvider implements DataProvider {
 	
-	private final String[] propertyNames;
 	
-	private Map<String, String> propertyToLabelMap;
+	private final ImList<String> propertyNames;
 	
+	private final @Nullable Map<String, String> propertyToLabelMap;
 	
-	public DefaultColumnHeaderDataProvider(final String[] columnLabels) {
-		this.propertyNames= columnLabels;
-	}
 	
-	public DefaultColumnHeaderDataProvider(final String[] propertyNames, final Map<String, String> propertyToLabelMap) {
-		this.propertyNames= propertyNames;
+	public PropertyColumnHeaderDataProvider(final ImList<String> propertyNames,
+			final Map<String, String> propertyToLabelMap) {
+		this.propertyNames= nonNullAssert(propertyNames);
 		this.propertyToLabelMap= propertyToLabelMap;
 	}
 	
 	
-	public String getColumnHeaderLabel(final long columnIndex) {
-		if (columnIndex >= Integer.MAX_VALUE) {
-			throw new IndexOutOfBoundsException();
-		}
-		final String propertyName= this.propertyNames[(int) columnIndex];
-		if (this.propertyToLabelMap != null) {
-			final String label= this.propertyToLabelMap.get(propertyName);
-			if (label != null) {
-				return label;
-			}
-		}
-		return propertyName;
-	}
-	
 	@Override
 	public long getColumnCount() {
-		return this.propertyNames.length;
+		return this.propertyNames.size();
 	}
 	
 	@Override
@@ -66,12 +56,23 @@ public class DefaultColumnHeaderDataProvider implements IDataProvider {
 	 * This class does not support multiple rows in the column header layer.
 	 */
 	@Override
-	public Object getDataValue(final long columnIndex, final long rowIndex, final int flags, final IProgressMonitor monitor) {
-		return getColumnHeaderLabel(columnIndex);
+	public Object getDataValue(final long columnIndex, final long rowIndex, final int flags,
+			final @Nullable IProgressMonitor monitor) {
+		if (columnIndex < 0 || columnIndex >= this.propertyNames.size()) {
+			throw new IndexOutOfBoundsException();
+		}
+		final String propertyName= this.propertyNames.get((int)columnIndex);
+		if (this.propertyToLabelMap != null) {
+			final String label= this.propertyToLabelMap.get(propertyName);
+			if (label != null) {
+				return label;
+			}
+		}
+		return propertyName;
 	}
 	
 	@Override
-	public void setDataValue(final long columnIndex, final long rowIndex, final Object newValue) {
+	public void setDataValue(final long columnIndex, final long rowIndex, final @Nullable Object newValue) {
 		throw new UnsupportedOperationException();
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IColumnPropertyResolver.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/PropertyColumnResolver.java
index ceefa29a..9376ba49 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/IColumnPropertyResolver.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/PropertyColumnResolver.java
@@ -11,14 +11,17 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.data;
+package org.eclipse.statet.ecommons.waltable.util.data;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 
 /**
  * Maps between the column property name in the backing data bean
  * and its corresponding column index.
  */
-public interface IColumnPropertyResolver {
+@NonNullByDefault
+public interface PropertyColumnResolver {
 	
 	
 	/**
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ReflectiveColumnPropertyAccessor.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/ReflectivePropertyColumnAccessor.java
index f8cbc82b..b06facea 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/data/ReflectiveColumnPropertyAccessor.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/util/data/ReflectivePropertyColumnAccessor.java
@@ -11,13 +11,12 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.data;
+package org.eclipse.statet.ecommons.waltable.util.data;
 
 import java.beans.IntrospectionException;
 import java.beans.Introspector;
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Method;
-import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -25,92 +24,106 @@ import java.util.Map;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.lang.NonNull;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
 import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;
 
 
 /**
- * Convenience class which uses java reflection to get/set property names
- *  from the row bean. It looks for getter methods for reading and setter
- *  methods for writing according to the Java conventions.
+ * Convenience class which uses java reflection to get/set property names from the row bean. It
+ * looks for getter methods for reading and setter methods for writing according to the Java
+ * conventions.
  * 
  * @param <R> type of the row object/bean
  */
-public class ReflectiveColumnPropertyAccessor<R> implements IColumnPropertyAccessor<R> {
+@NonNullByDefault
+public class ReflectivePropertyColumnAccessor<R> implements PropertyColumnAccessor<R> {
 	
 	
 	private final List<String> propertyNames;
-
-	private Map<String, PropertyDescriptor> propertyDescriptorMap;
-
+	
+	private final Map<Class<?>, Map<String, PropertyDescriptor>> propertyDescriptorMap= new HashMap<>();
+	
+	
 	/**
 	 * @param propertyNames of the members of the row bean
 	 */
-	public ReflectiveColumnPropertyAccessor(final String[] propertyNames) {
-		this.propertyNames= Arrays.asList(propertyNames);
+	public ReflectivePropertyColumnAccessor(final @NonNull String... propertyNames) {
+		this.propertyNames= ImCollections.newList(propertyNames);
 	}
-
+	
+	
 	@Override
 	public long getColumnCount() {
 		return this.propertyNames.size();
 	}
 
 	@Override
-	public Object getDataValue(final R rowObj, final long columnIndex) {
+	public @Nullable Object getDataValue(final R rowObj, final long columnIndex) {
 		try {
-			final PropertyDescriptor propertyDesc= getPropertyDescriptor(rowObj, columnIndex);
+			final PropertyDescriptor propertyDesc= getPropertyDescriptor(rowObj,
+					getColumnProperty(columnIndex) );
 			final Method readMethod= propertyDesc.getReadMethod();
 			return readMethod.invoke(rowObj);
-		} catch (final Exception e) {
+		}
+		catch (final Exception e) {
 			throw new RuntimeException(e);
 		}
 	}
-
+	
 	@Override
-	public void setDataValue(final R rowObj, final long columnIndex, final Object newValue) {
+	public void setDataValue(final @NonNull R rowObj, final long columnIndex, final @Nullable Object newValue) {
 		try {
-			final PropertyDescriptor propertyDesc= getPropertyDescriptor(rowObj, columnIndex);
+			final PropertyDescriptor propertyDesc= getPropertyDescriptor(rowObj,
+					getColumnProperty(columnIndex) );
 			final Method writeMethod= propertyDesc.getWriteMethod();
 			if (writeMethod == null) {
 				throw new RuntimeException("Setter method not found in backing bean for value at column index: " + columnIndex); //$NON-NLS-1$
 			}
 			writeMethod.invoke(rowObj, newValue);
-		} catch (final IllegalArgumentException ex) {
+		}
+		catch (final IllegalArgumentException ex) {
 			WaLTablePlugin.log(new Status(IStatus.WARNING, WaLTablePlugin.BUNDLE_ID,
 					"Data type being set does not match the data type of the setter method in the backing bean", ex )); //$NON-NLS-1$
-		} catch (final Exception e) {
+		}
+		catch (final Exception e) {
 			WaLTablePlugin.log(new Status(IStatus.ERROR, WaLTablePlugin.BUNDLE_ID,
 					"Error while setting data value", e )); //$NON-NLS-1$
 			throw new RuntimeException("Error while setting data value"); //$NON-NLS-1$
 		}
 	}
-
+	
 	@Override
 	public String getColumnProperty(final long columnIndex) {
-		if (columnIndex >= Integer.MAX_VALUE) {
+		if (columnIndex < 0 || columnIndex >= Integer.MAX_VALUE) {
 			throw new IndexOutOfBoundsException();
 		}
-		return this.propertyNames.get((int) columnIndex);
+		return this.propertyNames.get((int)columnIndex);
 	}
-
+	
 	@Override
 	public long getColumnIndex(final String propertyName) {
 		return this.propertyNames.indexOf(propertyName);
 	}
-
-	private PropertyDescriptor getPropertyDescriptor(final R rowObj, final long columnIndex) throws IntrospectionException {
-		if (columnIndex >= Integer.MAX_VALUE) {
-			throw new IndexOutOfBoundsException();
-		}
-		if (this.propertyDescriptorMap == null) {
-			this.propertyDescriptorMap= new HashMap<>();
-			final PropertyDescriptor[] propertyDescriptors= Introspector.getBeanInfo(rowObj.getClass()).getPropertyDescriptors();
-			for (final PropertyDescriptor propertyDescriptor : propertyDescriptors) {
-				this.propertyDescriptorMap.put(propertyDescriptor.getName(), propertyDescriptor);
+	
+	protected PropertyDescriptor getPropertyDescriptor(final @NonNull R rowObj,
+			final String propertyName) throws IntrospectionException {
+		synchronized (this.propertyDescriptorMap) {
+			var map= this.propertyDescriptorMap.get(rowObj.getClass());
+			if (map == null) {
+				final PropertyDescriptor[] propertyDescriptors=
+						Introspector.getBeanInfo(rowObj.getClass()).getPropertyDescriptors();
+				map= new HashMap<>();
+				for (final PropertyDescriptor propertyDescriptor : propertyDescriptors) {
+					map.put(propertyDescriptor.getName(), propertyDescriptor);
+				}
+				this.propertyDescriptorMap.put(rowObj.getClass(), map);
 			}
+			return map.get(propertyName);
 		}
-
-		final String propertyName= this.propertyNames.get((int) columnIndex);
-		return this.propertyDescriptorMap.get(propertyName);
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/RecalculateScrollBarsCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/RecalculateScrollBarsCommand.java
index 6b10646a..47c7eb65 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/RecalculateScrollBarsCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/RecalculateScrollBarsCommand.java
@@ -11,13 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractContextFreeCommand;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
+
+@NonNullByDefault
 public class RecalculateScrollBarsCommand extends AbstractContextFreeCommand {
 	
+	
 	public RecalculateScrollBarsCommand() {
 	}
+	
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/RecalculateScrollBarsCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/RecalculateScrollBarsCommandHandler.java
index 0d04a07b..cd766612 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/RecalculateScrollBarsCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/RecalculateScrollBarsCommandHandler.java
@@ -11,15 +11,20 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
 
+
+@NonNullByDefault
 public class RecalculateScrollBarsCommandHandler extends AbstractLayerCommandHandler<RecalculateScrollBarsCommand> {
 	
+	
 	private final ViewportLayer viewportLayer;
-
+	
+	
 	public RecalculateScrollBarsCommandHandler(final ViewportLayer viewportLayer) {
 		this.viewportLayer= viewportLayer;
 	}
@@ -28,11 +33,11 @@ public class RecalculateScrollBarsCommandHandler extends AbstractLayerCommandHan
 	public Class<RecalculateScrollBarsCommand> getCommandClass() {
 		return RecalculateScrollBarsCommand.class;
 	}
-
+	
 	@Override
 	protected boolean doCommand(final RecalculateScrollBarsCommand command) {
 		this.viewportLayer.recalculateScrollBars();
 		return true;
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollEvent.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollEvent.java
new file mode 100644
index 00000000..b7fdf9f0
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollEvent.java
@@ -0,0 +1,45 @@
+/*=============================================================================#
+ # Copyright (c) 2012, 2021 Original NatTable authors and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0
+ # 
+ # Contributors:
+ #     Original NatTable authors and others - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.viewport.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.GeneralStructuralChangeEvent;
+
+
+@NonNullByDefault
+public class ScrollEvent extends GeneralStructuralChangeEvent {
+	
+	
+	public ScrollEvent(final ViewportLayer viewportLayer) {
+		super(viewportLayer);
+	}
+	
+	protected ScrollEvent(final Layer event) {
+		super(event);
+	}
+	
+	@Override
+	public @Nullable ScrollEvent toLayer(final Layer targetLayer) {
+		if (targetLayer == getLayer()) {
+			return this;
+		}
+		
+		return new ScrollEvent(targetLayer);
+	}
+	
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollPageCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollPageCommand.java
index 7c341cf8..8c1ae69c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollPageCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollPageCommand.java
@@ -12,12 +12,15 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractRelativeCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractRelativeCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
 
+
+@NonNullByDefault
 public class ScrollPageCommand extends AbstractRelativeCommand {
 	
 	
@@ -25,14 +28,5 @@ public class ScrollPageCommand extends AbstractRelativeCommand {
 		super(direction, 1);
 	}
 	
-	protected ScrollPageCommand(final ScrollPageCommand command) {
-		super(command);
-	}
-	
-	@Override
-	public ScrollPageCommand cloneCommand() {
-		return new ScrollPageCommand(this);
-	}
-	
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollPageCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollPageCommandHandler.java
index 63919c69..8de22557 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollPageCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollPageCommandHandler.java
@@ -12,13 +12,16 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
 
-public class ScrollPageCommandHandler extends AbstractLayerCommandHandler<ScrollPageCommand> {
+
+@NonNullByDefault
+public class ScrollPageCommandHandler implements LayerCommandHandler<ScrollPageCommand> {
 	
 	
 	private final ViewportLayer viewportLayer;
@@ -35,14 +38,14 @@ public class ScrollPageCommandHandler extends AbstractLayerCommandHandler<Scroll
 	
 	
 	@Override
-	protected boolean doCommand(final ScrollPageCommand command) {
+	public boolean executeCommand(final ScrollPageCommand command) {
 		final Direction direction= command.getDirection();
-		final IViewportDim dim= this.viewportLayer.getDim(direction.getOrientation());
+		final var viewportDim= this.viewportLayer.getDim(direction.getOrientation());
 		if (direction.isBackward()) {
-			dim.scrollBackwardByPage();
+			viewportDim.scrollBackwardByPage();
 		}
 		else /*if (direction.isForward())*/ {
-			dim.scrollForwardByPage();
+			viewportDim.scrollForwardByPage();
 		}
 		return true;
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollStepCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollStepCommand.java
index 80b9b5ad..80d23f40 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollStepCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollStepCommand.java
@@ -12,12 +12,15 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractRelativeCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractRelativeCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
 
+
+@NonNullByDefault
 public class ScrollStepCommand extends AbstractRelativeCommand {
 	
 	
@@ -25,14 +28,5 @@ public class ScrollStepCommand extends AbstractRelativeCommand {
 		super(direction, 1);
 	}
 	
-	protected ScrollStepCommand(final ScrollStepCommand command) {
-		super(command);
-	}
-	
-	@Override
-	public ScrollStepCommand cloneCommand() {
-		return new ScrollStepCommand(this);
-	}
-	
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollStepCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollStepCommandHandler.java
index 68a9afc6..7e68899d 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollStepCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ScrollStepCommandHandler.java
@@ -12,13 +12,16 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
 
-public class ScrollStepCommandHandler extends AbstractLayerCommandHandler<ScrollStepCommand> {
+
+@NonNullByDefault
+public class ScrollStepCommandHandler implements LayerCommandHandler<ScrollStepCommand> {
 	
 	
 	private final ViewportLayer viewportLayer;
@@ -35,14 +38,14 @@ public class ScrollStepCommandHandler extends AbstractLayerCommandHandler<Scroll
 	
 	
 	@Override
-	protected boolean doCommand(final ScrollStepCommand command) {
+	public boolean executeCommand(final ScrollStepCommand command) {
 		final Direction direction= command.getDirection();
-		final IViewportDim dim= this.viewportLayer.getDim(direction.getOrientation());
+		final var viewportDim= this.viewportLayer.getDim(direction.getOrientation());
 		if (direction.isBackward()) {
-			dim.scrollBackwardByStep();
+			viewportDim.scrollBackwardByStep();
 		}
 		else /*if (direction.isForward())*/ {
-			dim.scrollForwardByStep();
+			viewportDim.scrollForwardByStep();
 		}
 		return true;
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/SelectRelativePageCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/SelectRelativePageCommand.java
index a93ca861..9f94b89b 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/SelectRelativePageCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/SelectRelativePageCommand.java
@@ -12,27 +12,21 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.Direction;
-import org.eclipse.statet.ecommons.waltable.selection.AbstractSelectRelativeCommand;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-
-public class SelectRelativePageCommand extends AbstractSelectRelativeCommand {
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Direction;
+import org.eclipse.statet.ecommons.waltable.selection.core.AbstractSelectRelativeCommand;
 
 
+@NonNullByDefault
+public class SelectRelativePageCommand extends AbstractSelectRelativeCommand {
+	
+	
 	public SelectRelativePageCommand(final Direction direction, final int selectionFlags) {
 		super(direction, 1, selectionFlags);
 	}
-
-	protected SelectRelativePageCommand(final SelectRelativePageCommand command) {
-		super(command);
-	}
-
-	@Override
-	public SelectRelativePageCommand cloneCommand() {
-		return new SelectRelativePageCommand(this);
-	}
-
-
+	
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/SelectRelativePageCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/SelectRelativePageCommandHandler.java
new file mode 100644
index 00000000..d6652e41
--- /dev/null
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/SelectRelativePageCommandHandler.java
@@ -0,0 +1,61 @@
+/*=============================================================================#
+ # Copyright (c) 2010, 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.waltable.viewport.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectRelativeCellCommand;
+
+
+@NonNullByDefault
+public class SelectRelativePageCommandHandler implements LayerCommandHandler<SelectRelativePageCommand> {
+	
+	
+	private final Layer viewportLayer;
+	
+	
+	public SelectRelativePageCommandHandler(final Layer viewportLayer) {
+		this.viewportLayer= viewportLayer;
+	}
+	
+	
+	@Override
+	public Class<SelectRelativePageCommand> getCommandClass() {
+		return SelectRelativePageCommand.class;
+	}
+	
+	@Override
+	public boolean executeCommand(final SelectRelativePageCommand command) {
+		long stepCount;
+		switch (command.getDirection()) {
+		case UP:
+		case DOWN:
+			stepCount= this.viewportLayer.getRowCount();
+			break;
+		case LEFT:
+		case RIGHT:
+			stepCount= this.viewportLayer.getColumnCount();
+			break;
+		default:
+			throw new IllegalStateException();
+		}
+		this.viewportLayer.doCommand(new SelectRelativeCellCommand(
+				command.getDirection(), stepCount, command.getSelectionFlags() ));
+		return true;
+	}
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ShowCellInViewportCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ShowCellInViewportCommand.java
index 5a43c654..72e82dfb 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ShowCellInViewportCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ShowCellInViewportCommand.java
@@ -11,15 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
 import org.eclipse.statet.ecommons.waltable.command.AbstractPositionCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
 
 
+@NonNullByDefault
 public class ShowCellInViewportCommand extends AbstractPositionCommand {
 	
-	public ShowCellInViewportCommand(final ILayer layer, final long columnPosition, final long rowPosition) {
+	
+	public ShowCellInViewportCommand(final Layer layer, final long columnPosition, final long rowPosition) {
 		super(layer, columnPosition, rowPosition);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ShowCellInViewportCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ShowCellInViewportCommandHandler.java
index 94fe98e1..19df0c19 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ShowCellInViewportCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ShowCellInViewportCommandHandler.java
@@ -11,14 +11,17 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
 
+
+@NonNullByDefault
 public class ShowCellInViewportCommandHandler extends AbstractLayerCommandHandler<ShowCellInViewportCommand> {
 	
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ShowDimPositionInViewportCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ShowDimPositionInViewportCommand.java
index 70fc4c4b..bbc20086 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ShowDimPositionInViewportCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ShowDimPositionInViewportCommand.java
@@ -11,16 +11,19 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractDimPositionCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractDimPositionCommand;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
 
+
+@NonNullByDefault
 public class ShowDimPositionInViewportCommand extends AbstractDimPositionCommand {
 	
 	
-	public ShowDimPositionInViewportCommand(final ILayerDim layerDim, final long position) {
+	public ShowDimPositionInViewportCommand(final LayerDim layerDim, final long position) {
 		super(layerDim, position);
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ShowPositionInViewportCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ShowDimPositionInViewportCommandHandler.java
index 3b8f4cf5..e8c58162 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ShowPositionInViewportCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ShowDimPositionInViewportCommandHandler.java
@@ -11,27 +11,34 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
 
-public class ShowPositionInViewportCommandHandler extends AbstractLayerCommandHandler<ShowDimPositionInViewportCommand> {
+
+@NonNullByDefault
+public class ShowDimPositionInViewportCommandHandler extends AbstractLayerCommandHandler<ShowDimPositionInViewportCommand> {
+	
+	
+	private final ViewportLayer viewportLayer;
 	
 	
-	public ShowPositionInViewportCommandHandler() {
+	public ShowDimPositionInViewportCommandHandler(final ViewportLayer viewportLayer) {
+		this.viewportLayer= viewportLayer;
 	}
 	
+	
 	@Override
 	public Class<ShowDimPositionInViewportCommand> getCommandClass() {
 		return ShowDimPositionInViewportCommand.class;
 	}
 	
-	
 	@Override
 	protected boolean doCommand(final ShowDimPositionInViewportCommand command) {
-		final IViewportDim dim= (IViewportDim) command.getDim();
-		dim.movePositionIntoViewport(command.getPosition());
+		final var viewportDim= this.viewportLayer.getDim(command.getOrientation());
+		viewportDim.movePositionIntoViewport(command.getPosition());
 		return true;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportDragCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportDragCommand.java
index 75ef483e..0c5fcf65 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportDragCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportDragCommand.java
@@ -11,17 +11,21 @@
  #     Edwin Park - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractContextFreeCommand;
 
-public class ViewportDragCommand implements ILayerCommand {
 
+@NonNullByDefault
+public class ViewportDragCommand extends AbstractContextFreeCommand {
+	
+	
 	private final long x;
 	private final long y;
-
+	
+	
 	public ViewportDragCommand(final long x, final long y) {
 		this.x= x;
 		this.y= y;
@@ -35,14 +39,4 @@ public class ViewportDragCommand implements ILayerCommand {
 		return this.y;
 	}
 	
-	@Override
-	public boolean convertToTargetLayer(final ILayer targetLayer) {
-		return true;
-	}
-
-	@Override
-	public ILayerCommand cloneCommand() {
-		return new ViewportDragCommand(this.x, this.y);
-	}
-
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportDragCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportDragCommandHandler.java
index 32876bbb..6016fa11 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportDragCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportDragCommandHandler.java
@@ -11,28 +11,35 @@
  #     Edwin Park - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommandHandler;
 
-public class ViewportDragCommandHandler extends AbstractLayerCommandHandler<ViewportDragCommand> {
 
+@NonNullByDefault
+public class ViewportDragCommandHandler implements LayerCommandHandler<ViewportDragCommand> {
+	
+	
 	private final ViewportLayer viewportLayer;
-
+	
+	
 	public ViewportDragCommandHandler(final ViewportLayer viewportLayer) {
 		this.viewportLayer= viewportLayer;
 	}
-
+	
+	
 	@Override
 	public Class<ViewportDragCommand> getCommandClass() {
 		return ViewportDragCommand.class;
 	}
-
+	
+	
 	@Override
-	protected boolean doCommand(final ViewportDragCommand command) {
+	public boolean executeCommand(final ViewportDragCommand command) {
 		this.viewportLayer.drag(command.getX(), command.getY());
 		return true;
 	}
-
+	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportLayer.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportLayer.java
index cd890199..3230ac3f 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportLayer.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportLayer.java
@@ -12,31 +12,32 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - dim-based implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
-import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.HORIZONTAL;
+import static org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation.VERTICAL;
 
 import org.eclipse.swt.widgets.Display;
 
-import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.grid.ClientAreaResizeCommand;
-import org.eclipse.statet.ecommons.waltable.layer.ILayer;
-import org.eclipse.statet.ecommons.waltable.layer.TransformLayer;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
-import org.eclipse.statet.ecommons.waltable.layer.event.IStructuralChangeEvent;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.command.LayerCommand;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRectangle;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.Layer;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerEvent;
+import org.eclipse.statet.ecommons.waltable.core.layer.TransformLayer;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralChangeEvent;
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
+import org.eclipse.statet.ecommons.waltable.grid.core.ClientAreaResizeCommand;
 import org.eclipse.statet.ecommons.waltable.print.PrintEntireGridCommand;
 import org.eclipse.statet.ecommons.waltable.print.TurnViewportOffCommand;
 import org.eclipse.statet.ecommons.waltable.print.TurnViewportOnCommand;
-import org.eclipse.statet.ecommons.waltable.selection.CellSelectionEvent;
-import org.eclipse.statet.ecommons.waltable.selection.ColumnSelectionEvent;
-import org.eclipse.statet.ecommons.waltable.selection.RowSelectionEvent;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
+import org.eclipse.statet.ecommons.waltable.selection.core.CellSelectionEvent;
+import org.eclipse.statet.ecommons.waltable.selection.core.DimSelectionEvent;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectionLayer;
 
 
 /**
@@ -46,14 +47,15 @@ import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
  * keeps them in sync with the data being displayed. This is typically placed over the
  * {@link SelectionLayer}.
  */
-public class ViewportLayer extends TransformLayer {
+@NonNullByDefault
+public class ViewportLayer extends TransformLayer<ViewportLayerDim> {
 	
 	static final int EDGE_HOVER_REGION_SIZE= 16;
 	
 	static final int PAGE_INTERSECTION_SIZE= EDGE_HOVER_REGION_SIZE;
 	
 	
-	private final ILayer scrollableLayer;
+	private final Layer scrollableLayer;
 	
 	// The viewport current origin
 	private boolean viewportOff= false;
@@ -68,15 +70,20 @@ public class ViewportLayer extends TransformLayer {
 	 * 
 	 * @param underlyingLayer the underlying scrollable layer
 	 */
-	public ViewportLayer(/*@NonNull*/ final ILayer underlyingLayer) {
+	public ViewportLayer(final Layer underlyingLayer) {
 		super(underlyingLayer);
 		this.scrollableLayer= underlyingLayer;
 		
-		registerCommandHandlers();
+		init();
 		
-		initDims();
+		registerCommandHandlers();
 	}
 	
+	@Override
+	protected ViewportLayerDimImpl createDim(final Orientation orientation) {
+		final Layer scrollable= getScrollableLayer();
+		return new ViewportLayerDimImpl(this, scrollable.getDim(orientation));
+	}
 	
 	@Override
 	public void dispose() {
@@ -95,32 +102,20 @@ public class ViewportLayer extends TransformLayer {
 	}
 	
 	
-	@Override
-	protected void initDims() {
-		final ILayer scrollable= getScrollableLayer();
-		if (scrollable == null) {
-			return;
-		}
-		for (final Orientation orientation : Orientation.values()) {
-			disposeDim(orientation);
-			setDim(new ViewportLayerDim(this, scrollable.getDim(orientation)));
-		}
-	}
-	
 	protected void disposeDim(final Orientation orientation) {
-		final ViewportLayerDim dim= get(orientation);
+		final ViewportLayerDimImpl dim= get(orientation);
 		if (dim != null) {
 			dim.dispose();
 		}
 	}
 	
 	@Override
-	public IViewportDim getDim(final Orientation orientation) {
-		return (IViewportDim) super.getDim(orientation);
+	public ViewportLayerDim getDim(final Orientation orientation) {
+		return super.getDim(orientation);
 	}
 	
-	final ViewportLayerDim get(final Orientation orientation) {
-		return (ViewportLayerDim) super.getDim(orientation);
+	final ViewportLayerDimImpl get(final Orientation orientation) {
+		return (ViewportLayerDimImpl)super.getDim(orientation);
 	}
 	
 	// Configuration
@@ -129,7 +124,7 @@ public class ViewportLayer extends TransformLayer {
 	protected void registerCommandHandlers() {
 		registerCommandHandler(new RecalculateScrollBarsCommandHandler(this));
 		registerCommandHandler(new ShowCellInViewportCommandHandler(this));
-		registerCommandHandler(new ShowPositionInViewportCommandHandler());
+		registerCommandHandler(new ShowDimPositionInViewportCommandHandler(this));
 		registerCommandHandler(new ViewportSelectDimPositionsCommandHandler(this));
 		registerCommandHandler(new ViewportDragCommandHandler(this));
 		registerCommandHandler(new SelectRelativePageCommandHandler(this));
@@ -141,7 +136,7 @@ public class ViewportLayer extends TransformLayer {
 	// Cell features
 	
 	@Override
-	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
+	public LayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
 		return super.getCellByPosition(columnPosition, rowPosition);
 	}
 	
@@ -150,32 +145,30 @@ public class ViewportLayer extends TransformLayer {
 	}
 	
 	@Override
-	public boolean doCommand(final ILayerCommand command) {
+	public boolean doCommand(final LayerCommand command) {
 		if (command instanceof ClientAreaResizeCommand) {
 			final ClientAreaResizeCommand clientAreaResizeCommand= (ClientAreaResizeCommand) command.cloneCommand();
-			if (clientAreaResizeCommand.convertToTargetLayer(this)) {
-				//remember the difference from client area to body region area
-				//needed because the scrollbar will be removed and therefore the client area will become bigger
-				final long widthDiff= clientAreaResizeCommand.getScrollable().getClientArea().width - clientAreaResizeCommand.getCalcArea().width;
-				final long heightDiff= clientAreaResizeCommand.getScrollable().getClientArea().height - clientAreaResizeCommand.getCalcArea().height;
-				
-				get(HORIZONTAL).checkScrollBar(clientAreaResizeCommand.getScrollable());
-				get(VERTICAL).checkScrollBar(clientAreaResizeCommand.getScrollable());
-				
-				get(HORIZONTAL).handleResize();
-				get(VERTICAL).handleResize();
-				
-				//after handling the scrollbars recalculate the area to use for percentage calculation
-				final LRectangle possibleArea= SWTUtil.toNatTable(clientAreaResizeCommand.getScrollable().getClientArea());
-				possibleArea.width-= widthDiff;
-				possibleArea.height-= heightDiff;
-				clientAreaResizeCommand.setCalcArea(possibleArea);
-				//we don't return true here because the ClientAreaResizeCommand needs to be handled
-				//by the DataLayer in case percentage sizing is enabled
-				//if we would return true, the DataLayer wouldn't be able to calculate the column/row
-				//sizes regarding the client area
-				return super.doCommand(clientAreaResizeCommand);
-			}
+			//remember the difference from client area to body region area
+			//needed because the scrollbar will be removed and therefore the client area will become bigger
+			final long widthDiff= clientAreaResizeCommand.getScrollable().getClientArea().width - clientAreaResizeCommand.getCalcArea().width;
+			final long heightDiff= clientAreaResizeCommand.getScrollable().getClientArea().height - clientAreaResizeCommand.getCalcArea().height;
+			
+			get(HORIZONTAL).checkScrollBar(clientAreaResizeCommand.getScrollable());
+			get(VERTICAL).checkScrollBar(clientAreaResizeCommand.getScrollable());
+			
+			get(HORIZONTAL).handleResize();
+			get(VERTICAL).handleResize();
+			
+			//after handling the scrollbars recalculate the area to use for percentage calculation
+			final LRectangle possibleArea= SwtUtils.toNatTable(clientAreaResizeCommand.getScrollable().getClientArea());
+			possibleArea.width-= widthDiff;
+			possibleArea.height-= heightDiff;
+			clientAreaResizeCommand.setCalcArea(possibleArea);
+			//we don't return true here because the ClientAreaResizeCommand needs to be handled
+			//by the DataLayer in case percentage sizing is enabled
+			//if we would return true, the DataLayer wouldn't be able to calculate the column/row
+			//sizes regarding the client area
+			return super.doCommand(clientAreaResizeCommand);
 		}
 		else if (command instanceof TurnViewportOffCommand) {
 			if (!isViewportOff()) {
@@ -215,23 +208,22 @@ public class ViewportLayer extends TransformLayer {
 	// Event handling
 	
 	@Override
-	public void handleLayerEvent(final ILayerEvent event) {
-		if (event instanceof IStructuralChangeEvent) {
-			final IStructuralChangeEvent structuralChangeEvent= (IStructuralChangeEvent) event;
-			if (structuralChangeEvent.isHorizontalStructureChanged()) {
-				get(HORIZONTAL).handleStructuralChange(structuralChangeEvent.getColumnDiffs());
-			}
-			if (structuralChangeEvent.isVerticalStructureChanged()) {
-				get(VERTICAL).handleStructuralChange(structuralChangeEvent.getRowDiffs());
+	public void handleLayerEvent(final LayerEvent event) {
+		if (event instanceof StructuralChangeEvent) {
+			final StructuralChangeEvent structuralChangeEvent= (StructuralChangeEvent)event;
+			for (final var orientation : Orientation.values()) {
+				if (structuralChangeEvent.isStructureChanged(orientation)) {
+					final var dim= get(orientation);
+					dim.handleStructuralChange(structuralChangeEvent.getDiffs(orientation));
+				}
 			}
 		}
 		
 		if (event instanceof CellSelectionEvent) {
 			processSelection((CellSelectionEvent) event);
-		} else if (event instanceof ColumnSelectionEvent) {
-			processColumnSelection((ColumnSelectionEvent) event);
-		} else if (event instanceof RowSelectionEvent) {
-			processRowSelection((RowSelectionEvent) event);
+		}
+		else if (event instanceof DimSelectionEvent) {
+			processDimSelection((DimSelectionEvent)event);
 		}
 		
 		super.handleLayerEvent(event);
@@ -249,34 +241,23 @@ public class ViewportLayer extends TransformLayer {
 	}
 	
 	/**
-	 * Handle {@link ColumnSelectionEvent}
+	 * Handle {@link DimSelectionEvent}
 	 * @param selectionEvent
 	 */
-	private void processColumnSelection(final ColumnSelectionEvent selectionEvent) {
-		final long explicitePosition= selectionEvent.getColumnPositionToReveal();
+	private void processDimSelection(final DimSelectionEvent selectionEvent) {
+		final long explicitePosition= selectionEvent.getPositionToReveal();
 		if (explicitePosition >= 0) {
-			get(HORIZONTAL).movePositionIntoViewport(explicitePosition);
+			get(selectionEvent.getOrientation()).movePositionIntoViewport(explicitePosition);
 		}
 	}
 	
-	/**
-	 * Handle {@link RowSelectionEvent}
-	 * @param selectionEvent
-	 */
-	private void processRowSelection(final RowSelectionEvent selectionEvent) {
-		final long explicitePosition= selectionEvent.getRowPositionToReveal();
-		if (explicitePosition >= 0) {
-			get(VERTICAL).movePositionIntoViewport(explicitePosition);
-			return;
-		}
-	}
 	
 	// Accessors
 	
 	/**
 	 * @return The scrollable layer underlying the viewport.
 	 */
-	public ILayer getScrollableLayer() {
+	public Layer getScrollableLayer() {
 		return this.scrollableLayer;
 	}
 	
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/IViewportDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportLayerDim.java
index fd296c58..f2011a44 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/IViewportDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportLayerDim.java
@@ -12,16 +12,25 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.TransformLayerDim;
 
 
 /**
  * Dimension of a viewport layer.
  */
-public interface IViewportDim extends ILayerDim {
+@NonNullByDefault
+public abstract class ViewportLayerDim extends TransformLayerDim<ViewportLayer> {
+	
+	
+	public ViewportLayerDim(final ViewportLayer layer, final LayerDim underlyingDim) {
+		super(layer, underlyingDim);
+	}
 	
 	
 	/**
@@ -29,7 +38,7 @@ public interface IViewportDim extends ILayerDim {
 	 * 
 	 * @return the underlying scrollable layer dimension
 	 */
-	ILayerDim getScrollable();
+	public abstract LayerDim getScrollable();
 	
 	
 	/**
@@ -37,14 +46,14 @@ public interface IViewportDim extends ILayerDim {
 	 * 
 	 * @return the pixel coordinate of the minimum origin in terms of the scrollable layer
 	 */
-	long getMinimumOriginPixel();
+	public abstract long getMinimumOriginPixel();
 	
 	/**
 	 * Returns the minimum origin.
 	 * 
 	 * @return the position of the minimum origin in terms of the scrollable layer
 	 */
-	long getMinimumOriginPosition();
+	public abstract long getMinimumOriginPosition();
 	
 	/**
 	 * Sets the minimum origin.
@@ -54,7 +63,7 @@ public interface IViewportDim extends ILayerDim {
 	 * 
 	 * @param scrollablePosition position of the origin in terms of the scrollable layer
 	 */
-	void setMinimumOriginPosition(long scrollablePosition);
+	public abstract void setMinimumOriginPosition(long scrollablePosition);
 	
 	
 	/**
@@ -62,14 +71,14 @@ public interface IViewportDim extends ILayerDim {
 	 * 
 	 * @return the pixel coordinate of the current origin in terms of the scrollable layer
 	 */
-	long getOriginPixel();
+	public abstract long getOriginPixel();
 	
 	/**
 	 * Returns the current origin.
 	 * 
 	 * @return the position of the current origin in terms of the scrollable layer
 	 */
-	long getOriginPosition();
+	public abstract long getOriginPosition();
 	
 	/**
 	 * Sets the current origin.
@@ -78,7 +87,7 @@ public interface IViewportDim extends ILayerDim {
 	 * 
 	 * @param scrollablePixel pixel coordinate of the origin in terms of the scrollable layer
 	 */
-	void setOriginPixel(long scrollablePixel);
+	public abstract void setOriginPixel(long scrollablePixel);
 	
 	/**
 	 * Sets the current origin.
@@ -87,7 +96,7 @@ public interface IViewportDim extends ILayerDim {
 	 * 
 	 * @throws PositionOutOfBoundsException if scrollablePosition is not a valid position
 	 */
-	void setOriginPosition(long scrollablePosition);
+	public abstract void setOriginPosition(long scrollablePosition);
 	
 	/**
 	 * Resets the viewport dimension.
@@ -99,7 +108,7 @@ public interface IViewportDim extends ILayerDim {
 	 * 
 	 * @throws PositionOutOfBoundsException if scrollablePosition is not a valid position
 	 */
-	void reset(long scrollablePosition);
+	public abstract void reset(long scrollablePosition);
 	
 	
 	/**
@@ -107,50 +116,50 @@ public interface IViewportDim extends ILayerDim {
 	 * 
 	 * @param scrollablePosition position in terms of the scrollable layer
 	 */
-	void movePositionIntoViewport(long scrollablePosition);
+	public abstract void movePositionIntoViewport(long scrollablePosition);
 	
 	
 	/**
 	 * Scrolls the viewport content backward by one step.
 	 */
-	void scrollBackwardByStep();
+	public abstract void scrollBackwardByStep();
 	
 	/**
 	 * Scrolls the viewport content forward by one step.
 	 */
-	void scrollForwardByStep();
+	public abstract void scrollForwardByStep();
 	
 	
 	/**
 	 * Scrolls the viewport content backward by one position.
 	 */
-	void scrollBackwardByPosition();
+	public abstract void scrollBackwardByPosition();
 	
 	/**
 	 * Scrolls the viewport content forward by one position.
 	 */
-	void scrollForwardByPosition();
+	public abstract void scrollForwardByPosition();
 	
 	
 	/**
 	 * Scrolls the viewport content backward by one viewport page.
 	 */
-	void scrollBackwardByPage();
+	public abstract void scrollBackwardByPage();
 	
 	/**
 	 * Scrolls the viewport content forward by one viewport page.
 	 */
-	void scrollForwardByPage();
+	public abstract void scrollForwardByPage();
 	
 	
 	/**
 	 * Scrolls the viewport content to the first position (minimum origin).
 	 */
-	void scrollBackwardToBound();
+	public abstract void scrollBackwardToBound();
 	
 	/**
 	 * Scrolls the viewport content to the last position.
 	 */
-	void scrollForwardToBound();
+	public abstract void scrollForwardToBound();
 	
 }
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportLayerDim.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportLayerDimImpl.java
index f6259c12..7ad6bdbe 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportLayerDim.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportLayerDimImpl.java
@@ -13,26 +13,26 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and dim-based implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import static org.eclipse.statet.ecommons.waltable.viewport.ViewportLayer.PAGE_INTERSECTION_SIZE;
+import static org.eclipse.statet.ecommons.waltable.viewport.core.ViewportLayer.PAGE_INTERSECTION_SIZE;
 
 import java.util.Collection;
 
-import org.eclipse.swt.widgets.ScrollBar;
-import org.eclipse.swt.widgets.Scrollable;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.PositionOutOfBoundsException;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.TransformLayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.PositionOutOfBoundsException;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.events.StructuralDiff;
+import org.eclipse.statet.ecommons.waltable.viewport.swt.ScrollBarHandler;
 
 
 /**
- * Implementation of {@link IViewportDim} for {@link ViewportLayer}.
+ * Implementation of {@link ViewportLayerDim} for {@link ViewportLayer}.
  */
-public class ViewportLayerDim extends TransformLayerDim<ViewportLayer> implements IViewportDim {
+@NonNullByDefault
+class ViewportLayerDimImpl extends ViewportLayerDim {
 	
 	
 	private long minimumOriginPosition;
@@ -46,10 +46,10 @@ public class ViewportLayerDim extends TransformLayerDim<ViewportLayer> implement
 	private long cachedPositionCount;
 	private long cachedSize;
 	
-	private ScrollBarHandler scrollBarHandler;
+	private @Nullable ScrollBarHandler scrollBarAdapter;
 	
 	
-	public ViewportLayerDim(/*@NonNull*/ final ViewportLayer layer, /*@NonNull*/ final ILayerDim underlyingDim) {
+	public ViewportLayerDimImpl(final ViewportLayer layer, final LayerDim underlyingDim) {
 		super(layer, underlyingDim);
 		
 		invalidateStructure();
@@ -57,9 +57,9 @@ public class ViewportLayerDim extends TransformLayerDim<ViewportLayer> implement
 	
 	
 	protected void dispose() {
-		if (this.scrollBarHandler != null) {
-			this.scrollBarHandler.dispose();
-			this.scrollBarHandler= null;
+		if (this.scrollBarAdapter != null) {
+			this.scrollBarAdapter.dispose();
+			this.scrollBarAdapter= null;
 		}
 	}
 	
@@ -68,8 +68,8 @@ public class ViewportLayerDim extends TransformLayerDim<ViewportLayer> implement
 	 *     information if the size has changed.
 	 */
 	protected long getClientAreaSize() {
-		final long clientAreaSize= SWTUtil.getRange(this.layer.getClientAreaProvider().getClientArea(),
-				this.orientation).size();
+		final long clientAreaSize= this.layer.getClientAreaProvider().getClientArea()
+				.getSize(this.orientation);
 		if (clientAreaSize != this.cachedClientAreaSize) {
 			invalidateStructure();
 			this.cachedClientAreaSize= clientAreaSize;
@@ -182,7 +182,7 @@ public class ViewportLayerDim extends TransformLayerDim<ViewportLayer> implement
 	
 	
 	@Override
-	public final ILayerDim getScrollable() {
+	public final LayerDim getScrollable() {
 		return this.underlyingDim;
 	}
 	
@@ -519,13 +519,9 @@ public class ViewportLayerDim extends TransformLayerDim<ViewportLayer> implement
 	}
 	
 	
-	protected void checkScrollBar(final Scrollable control) {
-		if (this.scrollBarHandler != null) {
-			return;
-		}
-		final ScrollBar scrollBar= SWTUtil.getScrollBar(control, this.orientation);
-		if (scrollBar != null) {
-			this.scrollBarHandler= new ScrollBarHandler(this, scrollBar);
+	protected void checkScrollBar(final Object control) {
+		if (this.scrollBarAdapter == null) {
+			this.scrollBarAdapter= ScrollBarHandler.create(this, control);
 		}
 	}
 	
@@ -533,8 +529,9 @@ public class ViewportLayerDim extends TransformLayerDim<ViewportLayer> implement
 	 * Adjusts scrollbar to sync with current state of viewport.
 	 */
 	private void adjustScrollBar() {
-		if (this.scrollBarHandler != null) {
-			this.scrollBarHandler.adjustScrollBar();
+		final var scrollBarAdapter= this.scrollBarAdapter;
+		if (scrollBarAdapter != null) {
+			scrollBarAdapter.adjustScrollBar();
 		}
 	}
 	
@@ -542,10 +539,10 @@ public class ViewportLayerDim extends TransformLayerDim<ViewportLayer> implement
 	 * Recalculate scrollbar characteristics;
 	 */
 	private void recalculateScrollBar() {
-		if (this.scrollBarHandler != null) {
-			this.scrollBarHandler.recalculateScrollBarSize();
+		if (this.scrollBarAdapter != null) {
+			this.scrollBarAdapter.recalculateScrollBarSize();
 			
-			if (!this.scrollBarHandler.getScrollBar().getEnabled()) {
+			if (!this.scrollBarAdapter.getScrollBar().getEnabled()) {
 				setOriginPosition(getMinimumOriginPosition());
 			}
 		}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportSelectDimPositionsCommand.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportSelectDimPositionsCommand.java
index 9c321648..27c56935 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportSelectDimPositionsCommand.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportSelectDimPositionsCommand.java
@@ -11,30 +11,33 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
 import java.util.Collection;
 
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.selection.AbstractSelectDimPositionsCommand;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.selection.core.AbstractSelectDimPositionsCommand;
 
 
 /**
  * Command to select column(s)/row(s) in the viewport.
  */
+@NonNullByDefault
 public class ViewportSelectDimPositionsCommand extends AbstractSelectDimPositionsCommand {
 	
 	
-	public ViewportSelectDimPositionsCommand(final ILayerDim dim,
+	public ViewportSelectDimPositionsCommand(final LayerDim layerDim,
 			final long position, final int selectionFlags) {
-		super(dim, position, selectionFlags);
+		super(layerDim, position, selectionFlags);
 	}
 	
-	public ViewportSelectDimPositionsCommand(final ILayerDim dim,
+	public ViewportSelectDimPositionsCommand(final LayerDim layerDim,
 			final long refPosition, final Collection<LRange> positions,
 			final long positionToReveal, final int selectionFlags) {
-		super(dim, refPosition, positions, positionToReveal, selectionFlags);
+		super(layerDim, refPosition, positions, positionToReveal, selectionFlags);
 	}
 	
 	protected ViewportSelectDimPositionsCommand(final ViewportSelectDimPositionsCommand command) {
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportSelectDimPositionsCommandHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportSelectDimPositionsCommandHandler.java
index fe32836d..910da01c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportSelectDimPositionsCommandHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/core/ViewportSelectDimPositionsCommandHandler.java
@@ -11,20 +11,24 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.core;
 
-import org.eclipse.statet.ecommons.waltable.command.AbstractLayerCommandHandler;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.AbstractLayer;
-import org.eclipse.statet.ecommons.waltable.selection.SelectDimPositionsCommand;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
 
+import org.eclipse.statet.ecommons.waltable.core.command.AbstractLayerCommandHandler;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.AbstractLayer;
+import org.eclipse.statet.ecommons.waltable.selection.core.SelectDimPositionsCommand;
 
+
+@NonNullByDefault
 public class ViewportSelectDimPositionsCommandHandler extends AbstractLayerCommandHandler<ViewportSelectDimPositionsCommand> {
 	
 	
 	private final AbstractLayer viewportLayer;
 	
-	private final Orientation orientation;
+	private final @Nullable Orientation orientation;
 	
 	
 	public ViewportSelectDimPositionsCommandHandler(final AbstractLayer viewportLayer) {
@@ -32,7 +36,7 @@ public class ViewportSelectDimPositionsCommandHandler extends AbstractLayerComma
 	}
 	
 	public ViewportSelectDimPositionsCommandHandler(final AbstractLayer viewportLayer,
-			final Orientation orientation) {
+			final @Nullable Orientation orientation) {
 		this.viewportLayer= viewportLayer;
 		this.orientation= orientation;
 	}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollBarHandler.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/swt/ScrollBarHandler.java
index 0ab0111e..e3571951 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ScrollBarHandler.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/swt/ScrollBarHandler.java
@@ -12,21 +12,38 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - dim-based implementation prepared for long datasets
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport;
+package org.eclipse.statet.ecommons.waltable.viewport.swt;
 
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.widgets.Event;
 import org.eclipse.swt.widgets.Listener;
 import org.eclipse.swt.widgets.ScrollBar;
+import org.eclipse.swt.widgets.Scrollable;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+import org.eclipse.statet.jcommons.lang.Nullable;
+
+import org.eclipse.statet.ecommons.waltable.core.swt.SwtUtils;
 import org.eclipse.statet.ecommons.waltable.edit.EditUtils;
-import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;
+import org.eclipse.statet.ecommons.waltable.viewport.core.ViewportLayerDim;
 
 
+@NonNullByDefault
 public class ScrollBarHandler implements Listener {
 	
 	
-	private final IViewportDim dim;
+	public static @Nullable ScrollBarHandler create(final ViewportLayerDim layerDim, final Object control) {
+		if (control instanceof Scrollable) {
+			final ScrollBar scrollBar= SwtUtils.getScrollBar((Scrollable)control, layerDim.getOrientation());
+			if (scrollBar != null) {
+				return new ScrollBarHandler(layerDim, scrollBar);
+			}
+		}
+		return null;
+	}
+	
+	
+	private final ViewportLayerDim dim;
 	
 	private final ScrollBar scrollBar;
 	
@@ -43,19 +60,19 @@ public class ScrollBarHandler implements Listener {
 	private boolean dragging= false;
 	
 	
-	public ScrollBarHandler(final IViewportDim dim, final ScrollBar scrollBar) {
+	public ScrollBarHandler(final ViewportLayerDim dim, final ScrollBar scrollBar) {
 		this.dim= dim;
 		this.scrollBar= scrollBar;
 		this.scrollBar.addListener(SWT.Selection, this);
 		
-		scrollBar.getParent().addListener(SWTUtil.getMouseWheelEventType(this.dim.getOrientation()), this);
+		scrollBar.getParent().addListener(SwtUtils.getMouseWheelEventType(this.dim.getOrientation()), this);
 	}
 	
 	
 	public void dispose() {
 		if (this.scrollBar != null && !this.scrollBar.isDisposed()) {
 			this.scrollBar.removeListener(SWT.Selection, this);
-			this.scrollBar.removeListener(SWTUtil.getMouseWheelEventType(this.dim.getOrientation()), this);
+			this.scrollBar.removeListener(SwtUtils.getMouseWheelEventType(this.dim.getOrientation()), this);
 		}
 	}
 	
@@ -121,11 +138,11 @@ public class ScrollBarHandler implements Listener {
 		}
 	}
 	
-	ScrollBar getScrollBar() {
+	public ScrollBar getScrollBar() {
 		return this.scrollBar;
 	}
 	
-	void adjustScrollBar() {
+	public void adjustScrollBar() {
 		if (this.scrollBar.isDisposed()) {
 			return;
 		}
@@ -134,7 +151,7 @@ public class ScrollBarHandler implements Listener {
 		this.scrollBar.setSelection((int) (this.factor * startPixel));
 	}
 	
-	void recalculateScrollBarSize() {
+	public void recalculateScrollBarSize() {
 		if (this.scrollBar.isDisposed()) {
 			return;
 		}
@@ -171,7 +188,8 @@ public class ScrollBarHandler implements Listener {
 			this.scrollBar.setThumb(viewportWindowSpan);
 			this.scrollBar.setEnabled(true);
 			this.scrollBar.setVisible(true);
-		} else {
+		}
+		else {
 			this.scrollBar.setThumb(max);
 			this.scrollBar.setEnabled(false);
 			this.scrollBar.setVisible(false);
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/action/ViewportSelectDimPositionsAction.java b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/ui/action/ViewportSelectDimPositionsAction.java
index 1ab48da5..93268a5c 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/action/ViewportSelectDimPositionsAction.java
+++ b/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/srcBase/org/eclipse/statet/ecommons/waltable/viewport/ui/action/ViewportSelectDimPositionsAction.java
@@ -11,27 +11,28 @@
  #     Original NatTable authors and others - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.viewport.action;
-
-import java.util.Collections;
-import java.util.List;
+package org.eclipse.statet.ecommons.waltable.viewport.ui.action;
 
 import org.eclipse.swt.events.MouseEvent;
 
+import org.eclipse.statet.jcommons.collections.ImCollections;
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
 import org.eclipse.statet.ecommons.waltable.NatTable;
-import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
-import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
-import org.eclipse.statet.ecommons.waltable.layer.ILayerDim;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
-import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCellDim;
-import org.eclipse.statet.ecommons.waltable.selection.SelectionFlags;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.LRange;
+import org.eclipse.statet.ecommons.waltable.core.coordinate.Orientation;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCell;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerCellDim;
+import org.eclipse.statet.ecommons.waltable.core.layer.LayerDim;
+import org.eclipse.statet.ecommons.waltable.selection.ui.action.SelectCellAction;
 import org.eclipse.statet.ecommons.waltable.ui.action.IMouseAction;
-import org.eclipse.statet.ecommons.waltable.viewport.ViewportSelectDimPositionsCommand;
+import org.eclipse.statet.ecommons.waltable.viewport.core.ViewportSelectDimPositionsCommand;
 
 
 /**
  * Action to select the column/row at the mouse position.
  */
+@NonNullByDefault
 public class ViewportSelectDimPositionsAction implements IMouseAction {
 	
 	
@@ -45,25 +46,25 @@ public class ViewportSelectDimPositionsAction implements IMouseAction {
 	
 	@Override
 	public void run(final NatTable natTable, final MouseEvent event) {
-		final ILayerCell cell= natTable.getCellByPosition(
+		final LayerCell cell= natTable.getCellByPosition(
 				natTable.getColumnPositionByX(event.x),
 				natTable.getRowPositionByY(event.y) );
 		if (cell == null) {
 			return;
 		}
-		final ILayerDim layerDim= natTable.getDim(this.orientation);
-		final ILayerCellDim cellDim= cell.getDim(this.orientation);
+		final LayerDim layerDim= natTable.getDim(this.orientation);
+		final LayerCellDim cellDim= cell.getDim(this.orientation);
 		if (cellDim.getPositionSpan() > 1) {
-			final List<LRange> positions= Collections.singletonList(
+			final var positions= ImCollections.newList(
 					new LRange(cellDim.getOriginPosition(), cellDim.getOriginPosition() + cellDim.getPositionSpan()) );
 			natTable.doCommand(new ViewportSelectDimPositionsCommand(layerDim,
 					cellDim.getPosition(), positions, cellDim.getPosition(),
-					SelectionFlags.swt2Flags(event.stateMask) ));
+					SelectCellAction.swt2Flags(event.stateMask) ));
 		}
 		else {
 			natTable.doCommand(new ViewportSelectDimPositionsCommand(layerDim,
 					cellDim.getPosition(),
-					SelectionFlags.swt2Flags(event.stateMask) ));
+					SelectCellAction.swt2Flags(event.stateMask) ));
 		}
 	}
 
diff --git a/jcommons/org.eclipse.statet.jcommons.util/src/org/eclipse/statet/jcommons/collections/IntIterator.java b/jcommons/org.eclipse.statet.jcommons.util/src/org/eclipse/statet/jcommons/collections/IntIterator.java
new file mode 100644
index 00000000..3c10bdb0
--- /dev/null
+++ b/jcommons/org.eclipse.statet.jcommons.util/src/org/eclipse/statet/jcommons/collections/IntIterator.java
@@ -0,0 +1,37 @@
+/*=============================================================================#
+ # Copyright (c) 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.jcommons.collections;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+
+@NonNullByDefault
+public interface IntIterator extends Iterator<Integer> {
+	
+	
+	/**
+	 * Returns the next value in the iteration.
+	 * <p>
+	 * Like {@link #next()}, but returns directly the primitiv value.
+	 * 
+	 * @return the next value in the iteration
+	 * @throws NoSuchElementException if the iteration has no more elements
+	 */
+	int nextValue();
+	
+}
diff --git a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/ILValueIterator.java b/jcommons/org.eclipse.statet.jcommons.util/src/org/eclipse/statet/jcommons/collections/LongIterator.java
index 586d43c0..dda4e0d9 100644
--- a/ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/coordinate/ILValueIterator.java
+++ b/jcommons/org.eclipse.statet.jcommons.util/src/org/eclipse/statet/jcommons/collections/LongIterator.java
@@ -1,5 +1,5 @@
 /*=============================================================================#
- # Copyright (c) 2013, 2021 Stephan Wahlbrink and others.
+ # Copyright (c) 2021 Stephan Wahlbrink and others.
  # 
  # This program and the accompanying materials are made available under the
  # terms of the Eclipse Public License 2.0 which is available at
@@ -12,13 +12,16 @@
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/
 
-package org.eclipse.statet.ecommons.waltable.coordinate;
+package org.eclipse.statet.jcommons.collections;
 
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 
-public interface ILValueIterator extends Iterator<Long> {
+
+@NonNullByDefault
+public interface LongIterator extends Iterator<Long> {
 	
 	
 	/**