cleanup for I20040420v20040420

30 files changed, 270 insertions, 244 deletions

diff --git a/bundles/org.eclipse.compare/buildnotes_compare.html b/bundles/org.eclipse.compare/buildnotes_compare.html
index eaa5851f9..92bc38b07 100644
--- a/bundles/org.eclipse.compare/buildnotes_compare.html
+++ b/bundles/org.eclipse.compare/buildnotes_compare.html
@@ -18,6 +18,8 @@ Eclipse Build Input April 20th 2004
 Problem reports fixed</h2>
 <a href="http://dev.eclipse.org/bugs/show_bug.cgi?id=54091">#54091</a>: Allow headless diff and merge<br>
 <a href="http://dev.eclipse.org/bugs/show_bug.cgi?id=51791">#51791</a>: Allow binding filenames to compare extensions<br>
+<a href="http://dev.eclipse.org/bugs/show_bug.cgi?id=52261">#52261</a>: DiffNode is missing setAncestor()<br>
+<a href="http://dev.eclipse.org/bugs/show_bug.cgi?id=59204">#59204</a>: NPE in CompareUIPlugin$CompareRegistry.search(...)<br>
 
 <h1>
 <hr WIDTH="100%"></h1>
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/CompareEditorInput.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/CompareEditorInput.java
index cbbbb4785..9b4423272 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/CompareEditorInput.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/CompareEditorInput.java
@@ -138,7 +138,7 @@ public abstract class CompareEditorInput implements IEditorInput, IPropertyChang
 		if (object instanceof Boolean)
 			fUseOutlineView= ((Boolean) object).booleanValue();
 
-		ResourceBundle bundle= CompareUIPlugin.getResourceBundle();
+		ResourceBundle bundle= CompareUI.getResourceBundle();
 		fIgnoreWhitespace= new IgnoreWhiteSpaceAction(bundle, configuration);
 		fShowPseudoConflicts= new ShowPseudoConflicts(bundle, configuration);
 
@@ -644,7 +644,7 @@ public abstract class CompareEditorInput implements IEditorInput, IPropertyChang
 	 * @return a compare viewer which is suitable for the given input object or <code>null</code>
 	 */
 	public Viewer findStructureViewer(Viewer oldViewer, ICompareInput input, Composite parent) {
-		return CompareUIPlugin.findStructureViewer(oldViewer, input, parent, fCompareConfiguration);
+		return CompareUI.findStructureViewer(oldViewer, input, parent, fCompareConfiguration);
 	}
 
 	/**
@@ -663,7 +663,7 @@ public abstract class CompareEditorInput implements IEditorInput, IPropertyChang
 	 */
 	public Viewer findContentViewer(Viewer oldViewer, ICompareInput input, Composite parent) {
 
-		Viewer newViewer= CompareUIPlugin.findContentViewer(oldViewer, input, parent, fCompareConfiguration);
+		Viewer newViewer= CompareUI.findContentViewer(oldViewer, input, parent, fCompareConfiguration);
 		
 		boolean isNewViewer= newViewer != oldViewer;
 		if (DEBUG) System.out.println("CompareEditorInput.findContentViewer: " + isNewViewer); //$NON-NLS-1$
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/CompareUI.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/CompareUI.java
index 6b8f0ee35..a158143e9 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/CompareUI.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/CompareUI.java
@@ -100,7 +100,7 @@ public final class CompareUI {
 	 * @return the plugin's resource bundle
 	 */
 	public static ResourceBundle getResourceBundle() {
-		return CompareUIPlugin.getResourceBundle();
+		return CompareUIPlugin.getDefault().getResourceBundle();
 	}
 	
 	/**
@@ -216,7 +216,7 @@ public final class CompareUI {
 	 *   stream merger has been registered
 	 */
 	public static IStreamMerger createStreamMerger(IContentType type) {
-	    return CompareUIPlugin.createStreamMerger(type);
+	    return CompareUIPlugin.getDefault().createStreamMerger(type);
 	}
 
 	/**
@@ -228,7 +228,7 @@ public final class CompareUI {
 	 *   stream merger has been registered
 	 */
 	public static IStreamMerger createStreamMerger(String type) {
-	    return CompareUIPlugin.createStreamMerger(type);
+	    return CompareUIPlugin.getDefault().createStreamMerger(type);
 	}
 
 	/**
@@ -247,7 +247,7 @@ public final class CompareUI {
 	public static Viewer findStructureViewer(Viewer oldViewer, ICompareInput input, Composite parent,
 				CompareConfiguration configuration) {
 
-		return CompareUIPlugin.findStructureViewer(oldViewer, input, parent, configuration);
+		return CompareUIPlugin.getDefault().findStructureViewer(oldViewer, input, parent, configuration);
 	}
 	
 	/**
@@ -265,7 +265,7 @@ public final class CompareUI {
 	 */
 	public static Viewer findContentViewer(Viewer oldViewer, ICompareInput input, Composite parent,
 			CompareConfiguration configuration) {
-		return CompareUIPlugin.findContentViewer(oldViewer, input, parent, configuration);
+		return CompareUIPlugin.getDefault().findContentViewer(oldViewer, input, parent, configuration);
 	}
 	
 	/**
@@ -289,7 +289,7 @@ public final class CompareUI {
 	public static Viewer findContentViewer(Viewer oldViewer, Object input, Composite parent,
 			CompareConfiguration configuration) {
 		
-		return CompareUIPlugin.findContentViewer(oldViewer, input, parent, configuration);
+		return CompareUIPlugin.getDefault().findContentViewer(oldViewer, input, parent, configuration);
 	}
 
 	/**
@@ -303,7 +303,7 @@ public final class CompareUI {
 	 * @since 2.0
 	 */
 	public static void addStructureViewerAlias(String type, String alias) {
-		CompareUIPlugin.addStructureViewerAlias(type, alias);
+		CompareUIPlugin.getDefault().addStructureViewerAlias(type, alias);
 	}
 	
 	/**
@@ -316,7 +316,7 @@ public final class CompareUI {
 	 * @since 2.0
 	 */
 	public static void removeAllStructureViewerAliases(String type) {
-		CompareUIPlugin.removeAllStructureViewerAliases(type);
+		CompareUIPlugin.getDefault().removeAllStructureViewerAliases(type);
 	}
 }
 
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/EditionSelectionDialog.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/EditionSelectionDialog.java
index 09f477f55..35920d115 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/EditionSelectionDialog.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/EditionSelectionDialog.java
@@ -274,7 +274,7 @@ public class EditionSelectionDialog extends ResizableDialog {
 		IStructureCreator structureCreator= null;
 		if (ppath != null) {
 			String type= target.getType();
-			StructureCreatorDescriptor scd= CompareUIPlugin.getStructureCreator(type);
+			StructureCreatorDescriptor scd= CompareUIPlugin.getDefault().getStructureCreator(type);
 			if (scd != null)
 				structureCreator= scd.createStructureCreator();
 		}
@@ -345,7 +345,7 @@ public class EditionSelectionDialog extends ResizableDialog {
 		IStructureCreator structureCreator= null;
 		if (ppath != null) {
 			String type= target.getType();
-			StructureCreatorDescriptor scd= CompareUIPlugin.getStructureCreator(type);
+			StructureCreatorDescriptor scd= CompareUIPlugin.getDefault().getStructureCreator(type);
 			if (scd != null)
 				structureCreator= scd.createStructureCreator();
 		}
@@ -750,7 +750,7 @@ public class EditionSelectionDialog extends ResizableDialog {
 				fStructuredComparePane= new CompareViewerSwitchingPane(hsplitter, SWT.BORDER | SWT.FLAT, true) {
 					protected Viewer getViewer(Viewer oldViewer, Object input) {
 						if (input instanceof ICompareInput)
-							return CompareUIPlugin.findStructureViewer(oldViewer, (ICompareInput)input, this, getCompareConfiguration());
+							return CompareUI.findStructureViewer(oldViewer, (ICompareInput)input, this, getCompareConfiguration());
 						return null;
 					}
 				};
@@ -795,7 +795,7 @@ public class EditionSelectionDialog extends ResizableDialog {
 		
 		fContentPane= new CompareViewerSwitchingPane(vsplitter, SWT.BORDER | SWT.FLAT) {
 			protected Viewer getViewer(Viewer oldViewer, Object input) {
-				return CompareUIPlugin.findContentViewer(oldViewer, input, this, getCompareConfiguration());	
+				return CompareUI.findContentViewer(oldViewer, input, this, getCompareConfiguration());	
 			}
 		};
 		vsplitter.setWeights(new int[] { 30, 70 });
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/IStreamMerger.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/IStreamMerger.java
index 90af61a40..a1715dba7 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/IStreamMerger.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/IStreamMerger.java
@@ -50,6 +50,7 @@ public interface IStreamMerger {
      * On success a status <code>IStatus.OK</code> is returned, on error a status <code>IStatus.ERROR</code>. 
      * If the merge operation cannot deal with conflicts, the code of the error status has the value <code>IStreamMerger.CONFLICT</code>.
      * For text oriented mergers the encoding for the input and output streams is honored.
+     * It is the responsibility of callers to close input and output streams. 
      * 
      * @param output the byte stream to which the merge result is written; the merger will not close the stream
      * @param outputEncoding the encoding to use when writing to the output stream
@@ -60,7 +61,7 @@ public interface IStreamMerger {
      * @param other the byte stream containing the target of the merge
      * @param otherEncoding the encoding of the other input byte stream
      * @param monitor reports progress of the merge operation
-     * @return returns an ISta
+     * @return returns the completion status of the operation
      */
 	IStatus merge(OutputStream output, String outputEncoding,
 			InputStream ancestor, String ancestorEncoding,
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/NavigationAction.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/NavigationAction.java
index c3bf5245c..69d3df826 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/NavigationAction.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/NavigationAction.java
@@ -41,7 +41,7 @@ public class NavigationAction extends Action {
 	 * @param next if <code>true</code> action goes to the next difference; otherwise to the previous difference.
 	 */
 	public NavigationAction(boolean next) {
-		this(CompareUIPlugin.getResourceBundle(), next);
+		this(CompareUI.getResourceBundle(), next);
 	}
 
 	/**
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/ZipFileStructureCreator.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/ZipFileStructureCreator.java
index 8f06ebc72..cccd4601f 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/ZipFileStructureCreator.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/ZipFileStructureCreator.java
@@ -98,7 +98,7 @@ public class ZipFileStructureCreator implements IStructureCreator {
 				entry= path.substring(0, pos);
 				path= path.substring(pos + 1);
 			} else if (entry.length() > 0) {
-				if (CompareUIPlugin.filter(path, false, true))
+				if (CompareUIPlugin.getDefault().filter(path, false, true))
 					return null;
 				ZipFile ze= new ZipFile(entry);
 				fChildren.put(entry, ze);
@@ -114,7 +114,7 @@ public class ZipFileStructureCreator implements IStructureCreator {
 			}
 
 			if (folder == null) {
-				if (path.length() > 0 && CompareUIPlugin.filter(path, true, true))
+				if (path.length() > 0 && CompareUIPlugin.getDefault().filter(path, true, true))
 					return null;
 				folder= new ZipFolder(entry);
 				fChildren.put(entry, folder);
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/AddFromHistoryDialog.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/AddFromHistoryDialog.java
index 3d323f541..9dddfcdb9 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/AddFromHistoryDialog.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/AddFromHistoryDialog.java
@@ -277,7 +277,7 @@ public class AddFromHistoryDialog extends ResizableDialog {
 		applyDialogFont(parent); // to avoid applying font to compare viewer
 		fContentPane= new CompareViewerSwitchingPane(vsplitter, SWT.BORDER | SWT.FLAT) {
 			protected Viewer getViewer(Viewer oldViewer, Object input) {
-				return CompareUIPlugin.findContentViewer(oldViewer, input, this, fCompareConfiguration);	
+				return CompareUI.findContentViewer(oldViewer, input, this, fCompareConfiguration);	
 			}
 		};
 		vsplitter.setWeights(new int[] { 30, 70 });
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareEditorContributor.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareEditorContributor.java
index 254d0d395..b6aa333f1 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareEditorContributor.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareEditorContributor.java
@@ -35,7 +35,7 @@ public class CompareEditorContributor extends EditorActionBarContributor {
 
 
 	public CompareEditorContributor() {
-		ResourceBundle bundle= CompareUIPlugin.getResourceBundle();
+		ResourceBundle bundle= CompareUI.getResourceBundle();
 		
 		fIgnoreWhitespace= new IgnoreWhiteSpaceAction(bundle, null);
 		WorkbenchHelp.setHelp(fIgnoreWhitespace, ICompareContextIds.IGNORE_WHITESPACE_ACTION);
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareFilter.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareFilter.java
index 5d1b1ae91..ea94d3ae4 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareFilter.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareFilter.java
@@ -28,6 +28,9 @@ public class CompareFilter {
 	public CompareFilter() {
 	}
 
+	/**
+	 * Returns true if path matches filter, that is if path should be filtered.
+	 */
 	public boolean filter(String path0, boolean folder, boolean isArchive) {
 		if (!folder && fExtraResourceFileFilters != null) {
 			char[] name= path0.toCharArray();
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareUIPlugin.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareUIPlugin.java
index e100722d4..26c08241e 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareUIPlugin.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareUIPlugin.java
@@ -91,8 +91,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
             String type= element.getAttribute(CONTENT_TYPE_ID_ATTRIBUTE);
             String id= element.getAttribute(idAttributeName);
             if (id == null)
-                System.err.println("no target id attribut found: " + idAttributeName);
-            // System.err.println("binding: " + type + " -> " + id);	    
+                logErrorMessage(Utilities.getFormattedString("CompareUIPlugin.targetIdAttributeMissing", idAttributeName)); //$NON-NLS-1$
             if (type != null && id != null && fIdMap != null) {
                 Object o= fIdMap.get(id);
                 if (o != null) {
@@ -102,16 +101,16 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
                             fContentTypeBindings= new HashMap();
                         fContentTypeBindings.put(ct, o);
                     } else {
-                        System.err.println("content type not found: " + type);
+                        logErrorMessage(Utilities.getFormattedString("CompareUIPlugin.contentTypeNotFound", type)); //$NON-NLS-1$
                     }
                 } else {
-                    	System.err.println("target not found: " + id);
+                    logErrorMessage(Utilities.getFormattedString("CompareUIPlugin.targetNotFound", id)); //$NON-NLS-1$
                 }
             }
 	    	}
 
 	    	Object search(IContentType type) {
-	    	    if (fContentTypeBindings != null) {
+	    	    if (type != null && fContentTypeBindings != null) {
 		    	    Object b= fContentTypeBindings.get(type);
 		    	    if (b != null)
 		    	        return b;
@@ -156,14 +155,13 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	private static final String STRUCTURE_CREATOR_EXTENSION_POINT= "structureCreators"; //$NON-NLS-1$
 		private static final String STRUCTURE_CREATOR= "structureCreator"; //$NON-NLS-1$
 		private static final String STRUCTURE_CREATOR_ID_ATTRIBUTE= "structureCreatorId"; //$NON-NLS-1$
+		
+	private static final String VIEWER_TAG= "viewer"; //$NON-NLS-1$
 	private static final String STRUCTURE_MERGE_VIEWER_EXTENSION_POINT= "structureMergeViewers"; //$NON-NLS-1$
-		private static final String STRUCTURE_MERGE_VIEWER= "structureMergeViewer"; //$NON-NLS-1$
 		private static final String STRUCTURE_MERGE_VIEWER_ID_ATTRIBUTE= "structureMergeViewerId"; //$NON-NLS-1$
 	private static final String CONTENT_MERGE_VIEWER_EXTENSION_POINT= "contentMergeViewers"; //$NON-NLS-1$
-		private static final String CONTENT_MERGE_VIEWER= "contentMergeViewer"; //$NON-NLS-1$
 		private static final String CONTENT_MERGE_VIEWER_ID_ATTRIBUTE= "contentMergeViewerId"; //$NON-NLS-1$
 	private static final String CONTENT_VIEWER_EXTENSION_POINT= "contentViewers"; //$NON-NLS-1$
-		private static final String CONTENT_VIEWER= "contentViewer"; //$NON-NLS-1$
 		private static final String CONTENT_VIEWER_ID_ATTRIBUTE= "contentViewerId"; //$NON-NLS-1$
 
 	private static final String CONTENT_TYPE_BINDING= "contentTypeBinding"; //$NON-NLS-1$
@@ -172,11 +170,16 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
   	private static final String COMPARE_EDITOR= PLUGIN_ID + ".CompareEditor"; //$NON-NLS-1$
 	
 	private static final String STRUCTUREVIEWER_ALIASES_PREFERENCE_NAME= "StructureViewerAliases";	//$NON-NLS-1$
-	
+
 	// content type
 	private static final IContentTypeManager fgContentTypeManager= Platform.getContentTypeManager();
 	private static final IContentType CT_TEXT= fgContentTypeManager.getContentType(IContentTypeManager.CT_TEXT);
 
+	/**
+	 * The plugin singleton.
+	 */
+	private static CompareUIPlugin fgComparePlugin;
+	
 	/** Maps type to icons */
 	private static Map fgImages= new Hashtable(10);
 	/** Maps type to ImageDescriptors */
@@ -184,20 +187,17 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	/** Maps ImageDescriptors to Images */
 	private static Map fgImages2= new Hashtable(10);
 	
-	private static CompareRegistry fgStreamMergers= new CompareRegistry();
-	private static CompareRegistry fgStructureCreators= new CompareRegistry();
-	private static CompareRegistry fgStructureMergeViewers= new CompareRegistry();
-	private static CompareRegistry fgContentViewers= new CompareRegistry();
-	private static CompareRegistry fgContentMergeViewers= new CompareRegistry();
-	
-	private static Map fgStructureViewerAliases= new Hashtable(10);
-	
 	private static List fgDisposeOnShutdownImages= new ArrayList();
 	
-	private static ResourceBundle fgResourceBundle;
+	private ResourceBundle fResourceBundle;
 
-	private static CompareUIPlugin fgComparePlugin;
-	
+	private CompareRegistry fStreamMergers= new CompareRegistry();
+	private CompareRegistry fStructureCreators= new CompareRegistry();
+	private CompareRegistry fStructureMergeViewers= new CompareRegistry();
+	private CompareRegistry fContentViewers= new CompareRegistry();
+	private CompareRegistry fContentMergeViewers= new CompareRegistry();
+
+	private Map fStructureViewerAliases= new Hashtable(10);
 	private CompareFilter fFilter;
 	private IPropertyChangeListener fPropertyChangeListener;
 	
@@ -215,12 +215,11 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	public CompareUIPlugin(IPluginDescriptor descriptor) {
 		super(descriptor);
 				
+		Assert.isTrue(fgComparePlugin == null);
 		fgComparePlugin= this;
 		
-		fgResourceBundle= descriptor.getResourceBundle();
-		
+		fResourceBundle= descriptor.getResourceBundle();
 		registerExtensions();
-		
 		initPreferenceStore();
 	}
 	
@@ -229,11 +228,37 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 */
 	protected void initializeDefaultPreferences(IPreferenceStore store) {
 		super.initializeDefaultPreferences(store);
-		
 		ComparePreferencePage.initDefaults(store);		
 	}
 	
 	/**
+	 * Returns the singleton instance of this plug-in runtime class.
+	 *
+	 * @return the compare plug-in instance
+	 */
+	public static CompareUIPlugin getDefault() {
+		return fgComparePlugin;
+	}
+	
+	/**
+	 * Returns this plug-in's resource bundle.
+	 *
+	 * @return the plugin's resource bundle
+	 */
+	public ResourceBundle getResourceBundle() {
+		return getDefault().fResourceBundle;
+	}
+	
+	/**
+	 * Returns this plug-in's unique identifier.
+	 *
+	 * @return the plugin's unique identifier
+	 */
+	public static String getPluginId() {
+		return getDefault().getDescriptor().getUniqueIdentifier();
+	}
+
+	/**
 	 * Registers all stream mergers, structure creators, content merge viewers, and structure merge viewers
 	 * that are found in the XML plugin files.
 	 */
@@ -246,9 +271,9 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 	    		if (CONTENT_TYPE_BINDING.equals(name)) {
-	    		    fgStreamMergers.createBinding(element, STREAM_MERGER_ID_ATTRIBUTE);
+	    		    fStreamMergers.createBinding(element, STREAM_MERGER_ID_ATTRIBUTE);
 	    		} else if (STREAM_MERGER.equals(name)) {
-				fgStreamMergers.register(element, new StreamMergerDescriptor(element));
+				fStreamMergers.register(element, new StreamMergerDescriptor(element));
 		    }
 		}
 				
@@ -258,9 +283,9 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 		    if (CONTENT_TYPE_BINDING.equals(name)) {
-		        fgStructureCreators.createBinding(element, STRUCTURE_CREATOR_ID_ATTRIBUTE);
+		        fStructureCreators.createBinding(element, STRUCTURE_CREATOR_ID_ATTRIBUTE);
 		    } else /* if (STRUCTURE_CREATOR.equals(name))*/ {
-		        fgStructureCreators.register(element, new StructureCreatorDescriptor(element));
+		        fStructureCreators.register(element, new StructureCreatorDescriptor(element));
 		    }
 		}
 				
@@ -270,9 +295,9 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 		    if (CONTENT_TYPE_BINDING.equals(name)) {
-		        fgStructureMergeViewers.createBinding(element, STRUCTURE_MERGE_VIEWER_ID_ATTRIBUTE);
-		    } else /* if (STRUCTURE_MERGEVIEWER.equals(name))*/ {
-		        fgStructureMergeViewers.register(element, new ViewerDescriptor(element));
+		        fStructureMergeViewers.createBinding(element, STRUCTURE_MERGE_VIEWER_ID_ATTRIBUTE);
+		    } else if (VIEWER_TAG.equals(name)) {
+		        fStructureMergeViewers.register(element, new ViewerDescriptor(element));
 		    }
 		}
 		
@@ -282,9 +307,9 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 		    if (CONTENT_TYPE_BINDING.equals(name)) {
-		        fgContentMergeViewers.createBinding(element, CONTENT_MERGE_VIEWER_ID_ATTRIBUTE);
-		    } else /* if (CONTENT_MERGEVIEWER.equals(name))*/ {
-		        fgContentMergeViewers.register(element, new ViewerDescriptor(element));
+		        fContentMergeViewers.createBinding(element, CONTENT_MERGE_VIEWER_ID_ATTRIBUTE);
+		    } else if (VIEWER_TAG.equals(name)) {
+		        fContentMergeViewers.register(element, new ViewerDescriptor(element));
 		    }
 		}
 		
@@ -294,31 +319,13 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 		    if (CONTENT_TYPE_BINDING.equals(name)) {
-		        fgContentViewers.createBinding(element, CONTENT_VIEWER_ID_ATTRIBUTE);
-		    } else /* if (CONTENT_VIEWER.equals(name))*/ {
-		        fgContentViewers.register(element, new ViewerDescriptor(element));
+		        fContentViewers.createBinding(element, CONTENT_VIEWER_ID_ATTRIBUTE);
+		    } else if (VIEWER_TAG.equals(name)) {
+		        fContentViewers.register(element, new ViewerDescriptor(element));
 		    }
 		}
 	}
 	
-	/**
-	 * Returns the singleton instance of this plug-in runtime class.
-	 *
-	 * @return the compare plug-in instance
-	 */
-	public static CompareUIPlugin getDefault() {
-		return fgComparePlugin;
-	}
-	
-	/**
-	 * Returns this plug-in's resource bundle.
-	 *
-	 * @return the plugin's resource bundle
-	 */
-	public static ResourceBundle getResourceBundle() {
-		return fgResourceBundle;
-	}
-	
 	public static IWorkbench getActiveWorkbench() {
 		CompareUIPlugin plugin= getDefault();
 		if (plugin == null)
@@ -386,10 +393,10 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		IPreferenceStore ps= getPreferenceStore();
 		if (ps != null) {
 			StringBuffer sb= new StringBuffer();
-			Iterator iter= fgStructureViewerAliases.keySet().iterator();
+			Iterator iter= fStructureViewerAliases.keySet().iterator();
 			while (iter.hasNext()) {
 				String key= (String) iter.next();
-				String alias= (String) fgStructureViewerAliases.get(key);
+				String alias= (String) fStructureViewerAliases.get(key);
 				sb.append(key);
 				sb.append('.');
 				sb.append(alias);
@@ -633,8 +640,8 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @return a descriptor for the given type, or <code>null</code> if no
 	 *   descriptor has been registered
 	 */
-	public static StructureCreatorDescriptor getStructureCreator(String type) {
-		return (StructureCreatorDescriptor) fgStructureCreators.search(type);
+	public StructureCreatorDescriptor getStructureCreator(String type) {
+		return (StructureCreatorDescriptor) fStructureCreators.search(type);
 	}
 	
 	/**
@@ -644,8 +651,8 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @return a stream merger for the given type, or <code>null</code> if no
 	 *   stream merger has been registered
 	 */
-	public static IStreamMerger createStreamMerger(String type) {
-		StreamMergerDescriptor descriptor= (StreamMergerDescriptor) fgStreamMergers.search(type);
+	public IStreamMerger createStreamMerger(String type) {
+		StreamMergerDescriptor descriptor= (StreamMergerDescriptor) fStreamMergers.search(type);
 		if (descriptor != null)
 			return descriptor.createStreamMerger();
 		return null;
@@ -658,8 +665,8 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @return a stream merger for the given type, or <code>null</code> if no
 	 *   stream merger has been registered
 	 */
-	public static IStreamMerger createStreamMerger(IContentType type) {
-		StreamMergerDescriptor descriptor= (StreamMergerDescriptor) fgStreamMergers.search(type);
+	public IStreamMerger createStreamMerger(IContentType type) {
+		StreamMergerDescriptor descriptor= (StreamMergerDescriptor) fStreamMergers.search(type);
 		if (descriptor != null)
 			return descriptor.createStreamMerger();
 		return null;
@@ -678,7 +685,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @param configuration a configuration which is passed to a newly created viewer
 	 * @return the compare viewer which is suitable for the given input object or <code>null</code>
 	 */
-	public static Viewer findStructureViewer(Viewer oldViewer, ICompareInput input, Composite parent,
+	public Viewer findStructureViewer(Viewer oldViewer, ICompareInput input, Composite parent,
 				CompareConfiguration configuration) {
 
 		if (input.getLeft() == null || input.getRight() == null)	// we don't show the structure of additions or deletions
@@ -687,7 +694,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		// content type search
 		IContentType ctype= getCommonType(getContentTypes(input));
 		if (ctype != null) {
-		    Viewer viewer= getViewer(fgStructureMergeViewers.search(ctype), oldViewer, parent, configuration);
+		    Viewer viewer= getViewer(fStructureMergeViewers.search(ctype), oldViewer, parent, configuration);
 		    if (viewer != null)
 		        return viewer;
 		}
@@ -697,11 +704,11 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		String type= null;
 		if (isHomogenous(types)) {
 			type= normalizeCase(types[0]);
-			IViewerDescriptor vd= (IViewerDescriptor) fgStructureMergeViewers.search(type);
+			IViewerDescriptor vd= (IViewerDescriptor) fStructureMergeViewers.search(type);
 			if (vd == null) {
-				String alias= (String) fgStructureViewerAliases.get(type);
+				String alias= (String) fStructureViewerAliases.get(type);
 				if (alias != null)
-					vd= (IViewerDescriptor) fgStructureMergeViewers.search(alias);
+					vd= (IViewerDescriptor) fStructureMergeViewers.search(alias);
 			}
 			if (vd != null)
 				return vd.createViewer(oldViewer, parent, configuration);
@@ -711,7 +718,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		// now we try to find a structurecreator for the generic StructureDiffViewer
 		
 		StructureCreatorDescriptor scc= null;
-		Object desc= fgStructureCreators.search(ctype);	// search for content type
+		Object desc= fStructureCreators.search(ctype);	// search for content type
 		if (desc instanceof StructureCreatorDescriptor)
 		    scc= (StructureCreatorDescriptor) desc;
 		if (scc == null && type != null)
@@ -740,7 +747,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @param configuration a configuration which is passed to a newly created viewer
 	 * @return the compare viewer which is suitable for the given input object or <code>null</code>
 	 */
-	public static Viewer findContentViewer(Viewer oldViewer, Object in, Composite parent, CompareConfiguration cc) {
+	public Viewer findContentViewer(Viewer oldViewer, Object in, Composite parent, CompareConfiguration cc) {
 		
 		if (in instanceof IStreamContentAccessor) {
 			String type= ITypedElement.TEXT_TYPE;
@@ -750,7 +757,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 			    		    
 			    IContentType ct= getContentType(tin);
 				if (ct != null) {
-					Viewer viewer= getViewer(fgContentViewers.search(ct), oldViewer, parent, cc);
+					Viewer viewer= getViewer(fContentViewers.search(ct), oldViewer, parent, cc);
 					if (viewer != null)
 						return viewer;
 				}
@@ -760,7 +767,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 					type= ty;
 			}
 			
-			Viewer viewer= getViewer(fgContentViewers.search(type), oldViewer, parent, cc);
+			Viewer viewer= getViewer(fContentViewers.search(type), oldViewer, parent, cc);
 			if (viewer != null)
 				return viewer;
 			// fallback
@@ -774,7 +781,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		
 		IContentType ctype= getCommonType(getContentTypes(input));
 		if (ctype != null) {
-			Viewer viewer= getViewer(fgContentMergeViewers.search(ctype), oldViewer, parent, cc);
+			Viewer viewer= getViewer(fContentMergeViewers.search(ctype), oldViewer, parent, cc);
 			if (viewer != null)
 				return viewer;
 		}
@@ -800,7 +807,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		}
 		
 		if (type != null) {
-			Viewer viewer= getViewer(fgContentMergeViewers.search(type), oldViewer, parent, cc);
+			Viewer viewer= getViewer(fContentMergeViewers.search(type), oldViewer, parent, cc);
 			if (viewer != null)
 				return viewer;
 		}
@@ -817,7 +824,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 			else
 				type= BINARY_TYPE;
 			
-			IViewerDescriptor vd= (IViewerDescriptor) fgContentMergeViewers.search(type);
+			IViewerDescriptor vd= (IViewerDescriptor) fContentMergeViewers.search(type);
 			if (vd != null)
 				return vd.createViewer(oldViewer, parent, cc);
 		}
@@ -1028,7 +1035,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 					if (pos > 0) {
 						String key= pair.substring(0, pos);
 						String alias= pair.substring(pos+1);
-						fgStructureViewerAliases.put(key, alias);
+						fStructureViewerAliases.put(key, alias);
 						//System.out.println("<" + key + "><" + alias + ">");
 					}
 				}
@@ -1045,13 +1052,13 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		}
 	}
 	
-	public static void addStructureViewerAlias(String type, String alias) {
-		fgStructureViewerAliases.put(normalizeCase(alias), normalizeCase(type));
+	public void addStructureViewerAlias(String type, String alias) {
+		fStructureViewerAliases.put(normalizeCase(alias), normalizeCase(type));
 	}
 	
-	public static void removeAllStructureViewerAliases(String type) {
+	public void removeAllStructureViewerAliases(String type) {
 		String t= normalizeCase(type);
-		Set entrySet= fgStructureViewerAliases.entrySet();
+		Set entrySet= fStructureViewerAliases.entrySet();
 		for (Iterator iter= entrySet.iterator(); iter.hasNext(); ) {
 			Map.Entry entry= (Map.Entry)iter.next();
 			if (entry.getValue().equals(t))
@@ -1087,6 +1094,18 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		return (IEditorPart[])result.toArray(new IEditorPart[result.size()]);
 	}
 		
+	public boolean filter(String name, boolean isFolder, boolean isArchive) {
+	    if (fFilter != null)
+	        return fFilter.filter(name, isFolder, isArchive);
+	    return false;
+	}
+
+	public static void logErrorMessage(String message) {
+		if (message == null)
+			message= ""; //$NON-NLS-1$
+		log(new Status(IStatus.ERROR, getPluginId(), INTERNAL_ERROR, message, null));
+	}
+
 	public static void log(Throwable e) {
 		log(new Status(IStatus.ERROR, getPluginId(), INTERNAL_ERROR, CompareMessages.getString("ComparePlugin.internal_error"), e)); //$NON-NLS-1$
 	}
@@ -1094,13 +1113,4 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	public static void log(IStatus status) {
 		getDefault().getLog().log(status);
 	}
-	
-	public static String getPluginId() {
-		return getDefault().getDescriptor().getUniqueIdentifier();
-	}
-
-	public static boolean filter(String name, boolean isFolder, boolean isArchive) {
-		CompareFilter f= getDefault().fFilter;
-		return f.filter(name, isFolder, isArchive);
-	}
 }
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/ResourceCompareInput.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/ResourceCompareInput.java
index fc76172f1..e26156dd8 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/ResourceCompareInput.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/ResourceCompareInput.java
@@ -86,7 +86,7 @@ class ResourceCompareInput extends CompareEditorInput {
 		}
 		protected IStructureComparator createChild(IResource child) {
 			String name= child.getName();
-			if (CompareUIPlugin.filter(name, child instanceof IContainer, false))
+			if (CompareUIPlugin.getDefault().filter(name, child instanceof IContainer, false))
 				return null;
 			return new FilteredBufferedResourceNode(child);
 		}
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/Utilities.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/Utilities.java
index d99e9204b..99089d379 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/Utilities.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/Utilities.java
@@ -37,6 +37,7 @@ import org.eclipse.core.runtime.Status;
 import org.eclipse.ui.*;
 
 import org.eclipse.compare.CompareConfiguration;
+import org.eclipse.compare.CompareUI;
 import org.eclipse.compare.IEncodedStreamContentAccessor;
 import org.eclipse.compare.IStreamContentAccessor;
 
@@ -287,7 +288,7 @@ public class Utilities {
 	
 	public static String getString(String key) {
 		try {
-			return CompareUIPlugin.getResourceBundle().getString(key);
+			return CompareUI.getResourceBundle().getString(key);
 		} catch (MissingResourceException e) {
 			return "!" + key + "!";//$NON-NLS-2$ //$NON-NLS-1$
 		}
@@ -295,7 +296,7 @@ public class Utilities {
 	
 	public static String getFormattedString(String key, String arg) {
 		try{
-			return MessageFormat.format(CompareUIPlugin.getResourceBundle().getString(key), new String[] { arg });
+			return MessageFormat.format(CompareUI.getResourceBundle().getString(key), new String[] { arg });
 		} catch (MissingResourceException e) {
 			return "!" + key + "!";//$NON-NLS-2$ //$NON-NLS-1$
 		}	
diff --git a/bundles/org.eclipse.compare/plugin.properties b/bundles/org.eclipse.compare/plugin.properties
index e7e6a6c21..80578f06a 100644
--- a/bundles/org.eclipse.compare/plugin.properties
+++ b/bundles/org.eclipse.compare/plugin.properties
@@ -27,11 +27,15 @@ contentViewers= Content Viewer
 # CompareUIPlugin
 #
 CompareUIPlugin.dialogTitle=Compare
-CompareUIPlugin.noActiveWorkbenchPage=Can't find active workbench page
+CompareUIPlugin.noActiveWorkbenchPage=Can''t find active workbench page
 CompareUIPlugin.compareFailed=Compare Failed
 CompareUIPlugin.openEditorError=Problems Opening Editor
 CompareUIPlugin.noDifferences=There are no differences between the selected inputs.
 
+CompareUIPlugin.targetIdAttributeMissing=target id attribut ''{0}'' missing
+CompareUIPlugin.contentTypeNotFound=content type ''{0}'' not found
+CompareUIPlugin.targetNotFound=target ''{0}'' not found
+
 #
 # Compare Editor
 #
diff --git a/bundles/org.eclipse.compare/plugin.xml b/bundles/org.eclipse.compare/plugin.xml
index d9c32a910..f16f25aa2 100644
--- a/bundles/org.eclipse.compare/plugin.xml
+++ b/bundles/org.eclipse.compare/plugin.xml
@@ -366,12 +366,4 @@
 	  </contentTypeBinding>
    </extension>
 
-
-	<extension point="org.eclipse.core.runtime.contentTypes">
-		<content-type id="foo" name="Foo Type" 	
-			base-type="org.eclipse.core.runtime.javaProperties"
-			file-extensions="foo"
-		/>
-	</extension>		 
-
 </plugin>
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/buildnotes_compare.html b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/buildnotes_compare.html
index eaa5851f9..92bc38b07 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/buildnotes_compare.html
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/buildnotes_compare.html
@@ -18,6 +18,8 @@ Eclipse Build Input April 20th 2004
 Problem reports fixed</h2>
 <a href="http://dev.eclipse.org/bugs/show_bug.cgi?id=54091">#54091</a>: Allow headless diff and merge<br>
 <a href="http://dev.eclipse.org/bugs/show_bug.cgi?id=51791">#51791</a>: Allow binding filenames to compare extensions<br>
+<a href="http://dev.eclipse.org/bugs/show_bug.cgi?id=52261">#52261</a>: DiffNode is missing setAncestor()<br>
+<a href="http://dev.eclipse.org/bugs/show_bug.cgi?id=59204">#59204</a>: NPE in CompareUIPlugin$CompareRegistry.search(...)<br>
 
 <h1>
 <hr WIDTH="100%"></h1>
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/CompareEditorInput.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/CompareEditorInput.java
index cbbbb4785..9b4423272 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/CompareEditorInput.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/CompareEditorInput.java
@@ -138,7 +138,7 @@ public abstract class CompareEditorInput implements IEditorInput, IPropertyChang
 		if (object instanceof Boolean)
 			fUseOutlineView= ((Boolean) object).booleanValue();
 
-		ResourceBundle bundle= CompareUIPlugin.getResourceBundle();
+		ResourceBundle bundle= CompareUI.getResourceBundle();
 		fIgnoreWhitespace= new IgnoreWhiteSpaceAction(bundle, configuration);
 		fShowPseudoConflicts= new ShowPseudoConflicts(bundle, configuration);
 
@@ -644,7 +644,7 @@ public abstract class CompareEditorInput implements IEditorInput, IPropertyChang
 	 * @return a compare viewer which is suitable for the given input object or <code>null</code>
 	 */
 	public Viewer findStructureViewer(Viewer oldViewer, ICompareInput input, Composite parent) {
-		return CompareUIPlugin.findStructureViewer(oldViewer, input, parent, fCompareConfiguration);
+		return CompareUI.findStructureViewer(oldViewer, input, parent, fCompareConfiguration);
 	}
 
 	/**
@@ -663,7 +663,7 @@ public abstract class CompareEditorInput implements IEditorInput, IPropertyChang
 	 */
 	public Viewer findContentViewer(Viewer oldViewer, ICompareInput input, Composite parent) {
 
-		Viewer newViewer= CompareUIPlugin.findContentViewer(oldViewer, input, parent, fCompareConfiguration);
+		Viewer newViewer= CompareUI.findContentViewer(oldViewer, input, parent, fCompareConfiguration);
 		
 		boolean isNewViewer= newViewer != oldViewer;
 		if (DEBUG) System.out.println("CompareEditorInput.findContentViewer: " + isNewViewer); //$NON-NLS-1$
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/CompareUI.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/CompareUI.java
index 6b8f0ee35..a158143e9 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/CompareUI.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/CompareUI.java
@@ -100,7 +100,7 @@ public final class CompareUI {
 	 * @return the plugin's resource bundle
 	 */
 	public static ResourceBundle getResourceBundle() {
-		return CompareUIPlugin.getResourceBundle();
+		return CompareUIPlugin.getDefault().getResourceBundle();
 	}
 	
 	/**
@@ -216,7 +216,7 @@ public final class CompareUI {
 	 *   stream merger has been registered
 	 */
 	public static IStreamMerger createStreamMerger(IContentType type) {
-	    return CompareUIPlugin.createStreamMerger(type);
+	    return CompareUIPlugin.getDefault().createStreamMerger(type);
 	}
 
 	/**
@@ -228,7 +228,7 @@ public final class CompareUI {
 	 *   stream merger has been registered
 	 */
 	public static IStreamMerger createStreamMerger(String type) {
-	    return CompareUIPlugin.createStreamMerger(type);
+	    return CompareUIPlugin.getDefault().createStreamMerger(type);
 	}
 
 	/**
@@ -247,7 +247,7 @@ public final class CompareUI {
 	public static Viewer findStructureViewer(Viewer oldViewer, ICompareInput input, Composite parent,
 				CompareConfiguration configuration) {
 
-		return CompareUIPlugin.findStructureViewer(oldViewer, input, parent, configuration);
+		return CompareUIPlugin.getDefault().findStructureViewer(oldViewer, input, parent, configuration);
 	}
 	
 	/**
@@ -265,7 +265,7 @@ public final class CompareUI {
 	 */
 	public static Viewer findContentViewer(Viewer oldViewer, ICompareInput input, Composite parent,
 			CompareConfiguration configuration) {
-		return CompareUIPlugin.findContentViewer(oldViewer, input, parent, configuration);
+		return CompareUIPlugin.getDefault().findContentViewer(oldViewer, input, parent, configuration);
 	}
 	
 	/**
@@ -289,7 +289,7 @@ public final class CompareUI {
 	public static Viewer findContentViewer(Viewer oldViewer, Object input, Composite parent,
 			CompareConfiguration configuration) {
 		
-		return CompareUIPlugin.findContentViewer(oldViewer, input, parent, configuration);
+		return CompareUIPlugin.getDefault().findContentViewer(oldViewer, input, parent, configuration);
 	}
 
 	/**
@@ -303,7 +303,7 @@ public final class CompareUI {
 	 * @since 2.0
 	 */
 	public static void addStructureViewerAlias(String type, String alias) {
-		CompareUIPlugin.addStructureViewerAlias(type, alias);
+		CompareUIPlugin.getDefault().addStructureViewerAlias(type, alias);
 	}
 	
 	/**
@@ -316,7 +316,7 @@ public final class CompareUI {
 	 * @since 2.0
 	 */
 	public static void removeAllStructureViewerAliases(String type) {
-		CompareUIPlugin.removeAllStructureViewerAliases(type);
+		CompareUIPlugin.getDefault().removeAllStructureViewerAliases(type);
 	}
 }
 
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/EditionSelectionDialog.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/EditionSelectionDialog.java
index 09f477f55..35920d115 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/EditionSelectionDialog.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/EditionSelectionDialog.java
@@ -274,7 +274,7 @@ public class EditionSelectionDialog extends ResizableDialog {
 		IStructureCreator structureCreator= null;
 		if (ppath != null) {
 			String type= target.getType();
-			StructureCreatorDescriptor scd= CompareUIPlugin.getStructureCreator(type);
+			StructureCreatorDescriptor scd= CompareUIPlugin.getDefault().getStructureCreator(type);
 			if (scd != null)
 				structureCreator= scd.createStructureCreator();
 		}
@@ -345,7 +345,7 @@ public class EditionSelectionDialog extends ResizableDialog {
 		IStructureCreator structureCreator= null;
 		if (ppath != null) {
 			String type= target.getType();
-			StructureCreatorDescriptor scd= CompareUIPlugin.getStructureCreator(type);
+			StructureCreatorDescriptor scd= CompareUIPlugin.getDefault().getStructureCreator(type);
 			if (scd != null)
 				structureCreator= scd.createStructureCreator();
 		}
@@ -750,7 +750,7 @@ public class EditionSelectionDialog extends ResizableDialog {
 				fStructuredComparePane= new CompareViewerSwitchingPane(hsplitter, SWT.BORDER | SWT.FLAT, true) {
 					protected Viewer getViewer(Viewer oldViewer, Object input) {
 						if (input instanceof ICompareInput)
-							return CompareUIPlugin.findStructureViewer(oldViewer, (ICompareInput)input, this, getCompareConfiguration());
+							return CompareUI.findStructureViewer(oldViewer, (ICompareInput)input, this, getCompareConfiguration());
 						return null;
 					}
 				};
@@ -795,7 +795,7 @@ public class EditionSelectionDialog extends ResizableDialog {
 		
 		fContentPane= new CompareViewerSwitchingPane(vsplitter, SWT.BORDER | SWT.FLAT) {
 			protected Viewer getViewer(Viewer oldViewer, Object input) {
-				return CompareUIPlugin.findContentViewer(oldViewer, input, this, getCompareConfiguration());	
+				return CompareUI.findContentViewer(oldViewer, input, this, getCompareConfiguration());	
 			}
 		};
 		vsplitter.setWeights(new int[] { 30, 70 });
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/IStreamMerger.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/IStreamMerger.java
index 90af61a40..a1715dba7 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/IStreamMerger.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/IStreamMerger.java
@@ -50,6 +50,7 @@ public interface IStreamMerger {
      * On success a status <code>IStatus.OK</code> is returned, on error a status <code>IStatus.ERROR</code>. 
      * If the merge operation cannot deal with conflicts, the code of the error status has the value <code>IStreamMerger.CONFLICT</code>.
      * For text oriented mergers the encoding for the input and output streams is honored.
+     * It is the responsibility of callers to close input and output streams. 
      * 
      * @param output the byte stream to which the merge result is written; the merger will not close the stream
      * @param outputEncoding the encoding to use when writing to the output stream
@@ -60,7 +61,7 @@ public interface IStreamMerger {
      * @param other the byte stream containing the target of the merge
      * @param otherEncoding the encoding of the other input byte stream
      * @param monitor reports progress of the merge operation
-     * @return returns an ISta
+     * @return returns the completion status of the operation
      */
 	IStatus merge(OutputStream output, String outputEncoding,
 			InputStream ancestor, String ancestorEncoding,
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/NavigationAction.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/NavigationAction.java
index c3bf5245c..69d3df826 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/NavigationAction.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/NavigationAction.java
@@ -41,7 +41,7 @@ public class NavigationAction extends Action {
 	 * @param next if <code>true</code> action goes to the next difference; otherwise to the previous difference.
 	 */
 	public NavigationAction(boolean next) {
-		this(CompareUIPlugin.getResourceBundle(), next);
+		this(CompareUI.getResourceBundle(), next);
 	}
 
 	/**
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/ZipFileStructureCreator.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/ZipFileStructureCreator.java
index 8f06ebc72..cccd4601f 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/ZipFileStructureCreator.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/ZipFileStructureCreator.java
@@ -98,7 +98,7 @@ public class ZipFileStructureCreator implements IStructureCreator {
 				entry= path.substring(0, pos);
 				path= path.substring(pos + 1);
 			} else if (entry.length() > 0) {
-				if (CompareUIPlugin.filter(path, false, true))
+				if (CompareUIPlugin.getDefault().filter(path, false, true))
 					return null;
 				ZipFile ze= new ZipFile(entry);
 				fChildren.put(entry, ze);
@@ -114,7 +114,7 @@ public class ZipFileStructureCreator implements IStructureCreator {
 			}
 
 			if (folder == null) {
-				if (path.length() > 0 && CompareUIPlugin.filter(path, true, true))
+				if (path.length() > 0 && CompareUIPlugin.getDefault().filter(path, true, true))
 					return null;
 				folder= new ZipFolder(entry);
 				fChildren.put(entry, folder);
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/AddFromHistoryDialog.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/AddFromHistoryDialog.java
index 3d323f541..9dddfcdb9 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/AddFromHistoryDialog.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/AddFromHistoryDialog.java
@@ -277,7 +277,7 @@ public class AddFromHistoryDialog extends ResizableDialog {
 		applyDialogFont(parent); // to avoid applying font to compare viewer
 		fContentPane= new CompareViewerSwitchingPane(vsplitter, SWT.BORDER | SWT.FLAT) {
 			protected Viewer getViewer(Viewer oldViewer, Object input) {
-				return CompareUIPlugin.findContentViewer(oldViewer, input, this, fCompareConfiguration);	
+				return CompareUI.findContentViewer(oldViewer, input, this, fCompareConfiguration);	
 			}
 		};
 		vsplitter.setWeights(new int[] { 30, 70 });
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareEditorContributor.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareEditorContributor.java
index 254d0d395..b6aa333f1 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareEditorContributor.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareEditorContributor.java
@@ -35,7 +35,7 @@ public class CompareEditorContributor extends EditorActionBarContributor {
 
 
 	public CompareEditorContributor() {
-		ResourceBundle bundle= CompareUIPlugin.getResourceBundle();
+		ResourceBundle bundle= CompareUI.getResourceBundle();
 		
 		fIgnoreWhitespace= new IgnoreWhiteSpaceAction(bundle, null);
 		WorkbenchHelp.setHelp(fIgnoreWhitespace, ICompareContextIds.IGNORE_WHITESPACE_ACTION);
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareFilter.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareFilter.java
index 5d1b1ae91..ea94d3ae4 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareFilter.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareFilter.java
@@ -28,6 +28,9 @@ public class CompareFilter {
 	public CompareFilter() {
 	}
 
+	/**
+	 * Returns true if path matches filter, that is if path should be filtered.
+	 */
 	public boolean filter(String path0, boolean folder, boolean isArchive) {
 		if (!folder && fExtraResourceFileFilters != null) {
 			char[] name= path0.toCharArray();
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareUIPlugin.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareUIPlugin.java
index e100722d4..26c08241e 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareUIPlugin.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareUIPlugin.java
@@ -91,8 +91,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
             String type= element.getAttribute(CONTENT_TYPE_ID_ATTRIBUTE);
             String id= element.getAttribute(idAttributeName);
             if (id == null)
-                System.err.println("no target id attribut found: " + idAttributeName);
-            // System.err.println("binding: " + type + " -> " + id);	    
+                logErrorMessage(Utilities.getFormattedString("CompareUIPlugin.targetIdAttributeMissing", idAttributeName)); //$NON-NLS-1$
             if (type != null && id != null && fIdMap != null) {
                 Object o= fIdMap.get(id);
                 if (o != null) {
@@ -102,16 +101,16 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
                             fContentTypeBindings= new HashMap();
                         fContentTypeBindings.put(ct, o);
                     } else {
-                        System.err.println("content type not found: " + type);
+                        logErrorMessage(Utilities.getFormattedString("CompareUIPlugin.contentTypeNotFound", type)); //$NON-NLS-1$
                     }
                 } else {
-                    	System.err.println("target not found: " + id);
+                    logErrorMessage(Utilities.getFormattedString("CompareUIPlugin.targetNotFound", id)); //$NON-NLS-1$
                 }
             }
 	    	}
 
 	    	Object search(IContentType type) {
-	    	    if (fContentTypeBindings != null) {
+	    	    if (type != null && fContentTypeBindings != null) {
 		    	    Object b= fContentTypeBindings.get(type);
 		    	    if (b != null)
 		    	        return b;
@@ -156,14 +155,13 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	private static final String STRUCTURE_CREATOR_EXTENSION_POINT= "structureCreators"; //$NON-NLS-1$
 		private static final String STRUCTURE_CREATOR= "structureCreator"; //$NON-NLS-1$
 		private static final String STRUCTURE_CREATOR_ID_ATTRIBUTE= "structureCreatorId"; //$NON-NLS-1$
+		
+	private static final String VIEWER_TAG= "viewer"; //$NON-NLS-1$
 	private static final String STRUCTURE_MERGE_VIEWER_EXTENSION_POINT= "structureMergeViewers"; //$NON-NLS-1$
-		private static final String STRUCTURE_MERGE_VIEWER= "structureMergeViewer"; //$NON-NLS-1$
 		private static final String STRUCTURE_MERGE_VIEWER_ID_ATTRIBUTE= "structureMergeViewerId"; //$NON-NLS-1$
 	private static final String CONTENT_MERGE_VIEWER_EXTENSION_POINT= "contentMergeViewers"; //$NON-NLS-1$
-		private static final String CONTENT_MERGE_VIEWER= "contentMergeViewer"; //$NON-NLS-1$
 		private static final String CONTENT_MERGE_VIEWER_ID_ATTRIBUTE= "contentMergeViewerId"; //$NON-NLS-1$
 	private static final String CONTENT_VIEWER_EXTENSION_POINT= "contentViewers"; //$NON-NLS-1$
-		private static final String CONTENT_VIEWER= "contentViewer"; //$NON-NLS-1$
 		private static final String CONTENT_VIEWER_ID_ATTRIBUTE= "contentViewerId"; //$NON-NLS-1$
 
 	private static final String CONTENT_TYPE_BINDING= "contentTypeBinding"; //$NON-NLS-1$
@@ -172,11 +170,16 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
   	private static final String COMPARE_EDITOR= PLUGIN_ID + ".CompareEditor"; //$NON-NLS-1$
 	
 	private static final String STRUCTUREVIEWER_ALIASES_PREFERENCE_NAME= "StructureViewerAliases";	//$NON-NLS-1$
-	
+
 	// content type
 	private static final IContentTypeManager fgContentTypeManager= Platform.getContentTypeManager();
 	private static final IContentType CT_TEXT= fgContentTypeManager.getContentType(IContentTypeManager.CT_TEXT);
 
+	/**
+	 * The plugin singleton.
+	 */
+	private static CompareUIPlugin fgComparePlugin;
+	
 	/** Maps type to icons */
 	private static Map fgImages= new Hashtable(10);
 	/** Maps type to ImageDescriptors */
@@ -184,20 +187,17 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	/** Maps ImageDescriptors to Images */
 	private static Map fgImages2= new Hashtable(10);
 	
-	private static CompareRegistry fgStreamMergers= new CompareRegistry();
-	private static CompareRegistry fgStructureCreators= new CompareRegistry();
-	private static CompareRegistry fgStructureMergeViewers= new CompareRegistry();
-	private static CompareRegistry fgContentViewers= new CompareRegistry();
-	private static CompareRegistry fgContentMergeViewers= new CompareRegistry();
-	
-	private static Map fgStructureViewerAliases= new Hashtable(10);
-	
 	private static List fgDisposeOnShutdownImages= new ArrayList();
 	
-	private static ResourceBundle fgResourceBundle;
+	private ResourceBundle fResourceBundle;
 
-	private static CompareUIPlugin fgComparePlugin;
-	
+	private CompareRegistry fStreamMergers= new CompareRegistry();
+	private CompareRegistry fStructureCreators= new CompareRegistry();
+	private CompareRegistry fStructureMergeViewers= new CompareRegistry();
+	private CompareRegistry fContentViewers= new CompareRegistry();
+	private CompareRegistry fContentMergeViewers= new CompareRegistry();
+
+	private Map fStructureViewerAliases= new Hashtable(10);
 	private CompareFilter fFilter;
 	private IPropertyChangeListener fPropertyChangeListener;
 	
@@ -215,12 +215,11 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	public CompareUIPlugin(IPluginDescriptor descriptor) {
 		super(descriptor);
 				
+		Assert.isTrue(fgComparePlugin == null);
 		fgComparePlugin= this;
 		
-		fgResourceBundle= descriptor.getResourceBundle();
-		
+		fResourceBundle= descriptor.getResourceBundle();
 		registerExtensions();
-		
 		initPreferenceStore();
 	}
 	
@@ -229,11 +228,37 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 */
 	protected void initializeDefaultPreferences(IPreferenceStore store) {
 		super.initializeDefaultPreferences(store);
-		
 		ComparePreferencePage.initDefaults(store);		
 	}
 	
 	/**
+	 * Returns the singleton instance of this plug-in runtime class.
+	 *
+	 * @return the compare plug-in instance
+	 */
+	public static CompareUIPlugin getDefault() {
+		return fgComparePlugin;
+	}
+	
+	/**
+	 * Returns this plug-in's resource bundle.
+	 *
+	 * @return the plugin's resource bundle
+	 */
+	public ResourceBundle getResourceBundle() {
+		return getDefault().fResourceBundle;
+	}
+	
+	/**
+	 * Returns this plug-in's unique identifier.
+	 *
+	 * @return the plugin's unique identifier
+	 */
+	public static String getPluginId() {
+		return getDefault().getDescriptor().getUniqueIdentifier();
+	}
+
+	/**
 	 * Registers all stream mergers, structure creators, content merge viewers, and structure merge viewers
 	 * that are found in the XML plugin files.
 	 */
@@ -246,9 +271,9 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 	    		if (CONTENT_TYPE_BINDING.equals(name)) {
-	    		    fgStreamMergers.createBinding(element, STREAM_MERGER_ID_ATTRIBUTE);
+	    		    fStreamMergers.createBinding(element, STREAM_MERGER_ID_ATTRIBUTE);
 	    		} else if (STREAM_MERGER.equals(name)) {
-				fgStreamMergers.register(element, new StreamMergerDescriptor(element));
+				fStreamMergers.register(element, new StreamMergerDescriptor(element));
 		    }
 		}
 				
@@ -258,9 +283,9 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 		    if (CONTENT_TYPE_BINDING.equals(name)) {
-		        fgStructureCreators.createBinding(element, STRUCTURE_CREATOR_ID_ATTRIBUTE);
+		        fStructureCreators.createBinding(element, STRUCTURE_CREATOR_ID_ATTRIBUTE);
 		    } else /* if (STRUCTURE_CREATOR.equals(name))*/ {
-		        fgStructureCreators.register(element, new StructureCreatorDescriptor(element));
+		        fStructureCreators.register(element, new StructureCreatorDescriptor(element));
 		    }
 		}
 				
@@ -270,9 +295,9 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 		    if (CONTENT_TYPE_BINDING.equals(name)) {
-		        fgStructureMergeViewers.createBinding(element, STRUCTURE_MERGE_VIEWER_ID_ATTRIBUTE);
-		    } else /* if (STRUCTURE_MERGEVIEWER.equals(name))*/ {
-		        fgStructureMergeViewers.register(element, new ViewerDescriptor(element));
+		        fStructureMergeViewers.createBinding(element, STRUCTURE_MERGE_VIEWER_ID_ATTRIBUTE);
+		    } else if (VIEWER_TAG.equals(name)) {
+		        fStructureMergeViewers.register(element, new ViewerDescriptor(element));
 		    }
 		}
 		
@@ -282,9 +307,9 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 		    if (CONTENT_TYPE_BINDING.equals(name)) {
-		        fgContentMergeViewers.createBinding(element, CONTENT_MERGE_VIEWER_ID_ATTRIBUTE);
-		    } else /* if (CONTENT_MERGEVIEWER.equals(name))*/ {
-		        fgContentMergeViewers.register(element, new ViewerDescriptor(element));
+		        fContentMergeViewers.createBinding(element, CONTENT_MERGE_VIEWER_ID_ATTRIBUTE);
+		    } else if (VIEWER_TAG.equals(name)) {
+		        fContentMergeViewers.register(element, new ViewerDescriptor(element));
 		    }
 		}
 		
@@ -294,31 +319,13 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		    IConfigurationElement element= elements[i];
 		    String name= element.getName();
 		    if (CONTENT_TYPE_BINDING.equals(name)) {
-		        fgContentViewers.createBinding(element, CONTENT_VIEWER_ID_ATTRIBUTE);
-		    } else /* if (CONTENT_VIEWER.equals(name))*/ {
-		        fgContentViewers.register(element, new ViewerDescriptor(element));
+		        fContentViewers.createBinding(element, CONTENT_VIEWER_ID_ATTRIBUTE);
+		    } else if (VIEWER_TAG.equals(name)) {
+		        fContentViewers.register(element, new ViewerDescriptor(element));
 		    }
 		}
 	}
 	
-	/**
-	 * Returns the singleton instance of this plug-in runtime class.
-	 *
-	 * @return the compare plug-in instance
-	 */
-	public static CompareUIPlugin getDefault() {
-		return fgComparePlugin;
-	}
-	
-	/**
-	 * Returns this plug-in's resource bundle.
-	 *
-	 * @return the plugin's resource bundle
-	 */
-	public static ResourceBundle getResourceBundle() {
-		return fgResourceBundle;
-	}
-	
 	public static IWorkbench getActiveWorkbench() {
 		CompareUIPlugin plugin= getDefault();
 		if (plugin == null)
@@ -386,10 +393,10 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		IPreferenceStore ps= getPreferenceStore();
 		if (ps != null) {
 			StringBuffer sb= new StringBuffer();
-			Iterator iter= fgStructureViewerAliases.keySet().iterator();
+			Iterator iter= fStructureViewerAliases.keySet().iterator();
 			while (iter.hasNext()) {
 				String key= (String) iter.next();
-				String alias= (String) fgStructureViewerAliases.get(key);
+				String alias= (String) fStructureViewerAliases.get(key);
 				sb.append(key);
 				sb.append('.');
 				sb.append(alias);
@@ -633,8 +640,8 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @return a descriptor for the given type, or <code>null</code> if no
 	 *   descriptor has been registered
 	 */
-	public static StructureCreatorDescriptor getStructureCreator(String type) {
-		return (StructureCreatorDescriptor) fgStructureCreators.search(type);
+	public StructureCreatorDescriptor getStructureCreator(String type) {
+		return (StructureCreatorDescriptor) fStructureCreators.search(type);
 	}
 	
 	/**
@@ -644,8 +651,8 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @return a stream merger for the given type, or <code>null</code> if no
 	 *   stream merger has been registered
 	 */
-	public static IStreamMerger createStreamMerger(String type) {
-		StreamMergerDescriptor descriptor= (StreamMergerDescriptor) fgStreamMergers.search(type);
+	public IStreamMerger createStreamMerger(String type) {
+		StreamMergerDescriptor descriptor= (StreamMergerDescriptor) fStreamMergers.search(type);
 		if (descriptor != null)
 			return descriptor.createStreamMerger();
 		return null;
@@ -658,8 +665,8 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @return a stream merger for the given type, or <code>null</code> if no
 	 *   stream merger has been registered
 	 */
-	public static IStreamMerger createStreamMerger(IContentType type) {
-		StreamMergerDescriptor descriptor= (StreamMergerDescriptor) fgStreamMergers.search(type);
+	public IStreamMerger createStreamMerger(IContentType type) {
+		StreamMergerDescriptor descriptor= (StreamMergerDescriptor) fStreamMergers.search(type);
 		if (descriptor != null)
 			return descriptor.createStreamMerger();
 		return null;
@@ -678,7 +685,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @param configuration a configuration which is passed to a newly created viewer
 	 * @return the compare viewer which is suitable for the given input object or <code>null</code>
 	 */
-	public static Viewer findStructureViewer(Viewer oldViewer, ICompareInput input, Composite parent,
+	public Viewer findStructureViewer(Viewer oldViewer, ICompareInput input, Composite parent,
 				CompareConfiguration configuration) {
 
 		if (input.getLeft() == null || input.getRight() == null)	// we don't show the structure of additions or deletions
@@ -687,7 +694,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		// content type search
 		IContentType ctype= getCommonType(getContentTypes(input));
 		if (ctype != null) {
-		    Viewer viewer= getViewer(fgStructureMergeViewers.search(ctype), oldViewer, parent, configuration);
+		    Viewer viewer= getViewer(fStructureMergeViewers.search(ctype), oldViewer, parent, configuration);
 		    if (viewer != null)
 		        return viewer;
 		}
@@ -697,11 +704,11 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		String type= null;
 		if (isHomogenous(types)) {
 			type= normalizeCase(types[0]);
-			IViewerDescriptor vd= (IViewerDescriptor) fgStructureMergeViewers.search(type);
+			IViewerDescriptor vd= (IViewerDescriptor) fStructureMergeViewers.search(type);
 			if (vd == null) {
-				String alias= (String) fgStructureViewerAliases.get(type);
+				String alias= (String) fStructureViewerAliases.get(type);
 				if (alias != null)
-					vd= (IViewerDescriptor) fgStructureMergeViewers.search(alias);
+					vd= (IViewerDescriptor) fStructureMergeViewers.search(alias);
 			}
 			if (vd != null)
 				return vd.createViewer(oldViewer, parent, configuration);
@@ -711,7 +718,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		// now we try to find a structurecreator for the generic StructureDiffViewer
 		
 		StructureCreatorDescriptor scc= null;
-		Object desc= fgStructureCreators.search(ctype);	// search for content type
+		Object desc= fStructureCreators.search(ctype);	// search for content type
 		if (desc instanceof StructureCreatorDescriptor)
 		    scc= (StructureCreatorDescriptor) desc;
 		if (scc == null && type != null)
@@ -740,7 +747,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	 * @param configuration a configuration which is passed to a newly created viewer
 	 * @return the compare viewer which is suitable for the given input object or <code>null</code>
 	 */
-	public static Viewer findContentViewer(Viewer oldViewer, Object in, Composite parent, CompareConfiguration cc) {
+	public Viewer findContentViewer(Viewer oldViewer, Object in, Composite parent, CompareConfiguration cc) {
 		
 		if (in instanceof IStreamContentAccessor) {
 			String type= ITypedElement.TEXT_TYPE;
@@ -750,7 +757,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 			    		    
 			    IContentType ct= getContentType(tin);
 				if (ct != null) {
-					Viewer viewer= getViewer(fgContentViewers.search(ct), oldViewer, parent, cc);
+					Viewer viewer= getViewer(fContentViewers.search(ct), oldViewer, parent, cc);
 					if (viewer != null)
 						return viewer;
 				}
@@ -760,7 +767,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 					type= ty;
 			}
 			
-			Viewer viewer= getViewer(fgContentViewers.search(type), oldViewer, parent, cc);
+			Viewer viewer= getViewer(fContentViewers.search(type), oldViewer, parent, cc);
 			if (viewer != null)
 				return viewer;
 			// fallback
@@ -774,7 +781,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		
 		IContentType ctype= getCommonType(getContentTypes(input));
 		if (ctype != null) {
-			Viewer viewer= getViewer(fgContentMergeViewers.search(ctype), oldViewer, parent, cc);
+			Viewer viewer= getViewer(fContentMergeViewers.search(ctype), oldViewer, parent, cc);
 			if (viewer != null)
 				return viewer;
 		}
@@ -800,7 +807,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		}
 		
 		if (type != null) {
-			Viewer viewer= getViewer(fgContentMergeViewers.search(type), oldViewer, parent, cc);
+			Viewer viewer= getViewer(fContentMergeViewers.search(type), oldViewer, parent, cc);
 			if (viewer != null)
 				return viewer;
 		}
@@ -817,7 +824,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 			else
 				type= BINARY_TYPE;
 			
-			IViewerDescriptor vd= (IViewerDescriptor) fgContentMergeViewers.search(type);
+			IViewerDescriptor vd= (IViewerDescriptor) fContentMergeViewers.search(type);
 			if (vd != null)
 				return vd.createViewer(oldViewer, parent, cc);
 		}
@@ -1028,7 +1035,7 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 					if (pos > 0) {
 						String key= pair.substring(0, pos);
 						String alias= pair.substring(pos+1);
-						fgStructureViewerAliases.put(key, alias);
+						fStructureViewerAliases.put(key, alias);
 						//System.out.println("<" + key + "><" + alias + ">");
 					}
 				}
@@ -1045,13 +1052,13 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		}
 	}
 	
-	public static void addStructureViewerAlias(String type, String alias) {
-		fgStructureViewerAliases.put(normalizeCase(alias), normalizeCase(type));
+	public void addStructureViewerAlias(String type, String alias) {
+		fStructureViewerAliases.put(normalizeCase(alias), normalizeCase(type));
 	}
 	
-	public static void removeAllStructureViewerAliases(String type) {
+	public void removeAllStructureViewerAliases(String type) {
 		String t= normalizeCase(type);
-		Set entrySet= fgStructureViewerAliases.entrySet();
+		Set entrySet= fStructureViewerAliases.entrySet();
 		for (Iterator iter= entrySet.iterator(); iter.hasNext(); ) {
 			Map.Entry entry= (Map.Entry)iter.next();
 			if (entry.getValue().equals(t))
@@ -1087,6 +1094,18 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 		return (IEditorPart[])result.toArray(new IEditorPart[result.size()]);
 	}
 		
+	public boolean filter(String name, boolean isFolder, boolean isArchive) {
+	    if (fFilter != null)
+	        return fFilter.filter(name, isFolder, isArchive);
+	    return false;
+	}
+
+	public static void logErrorMessage(String message) {
+		if (message == null)
+			message= ""; //$NON-NLS-1$
+		log(new Status(IStatus.ERROR, getPluginId(), INTERNAL_ERROR, message, null));
+	}
+
 	public static void log(Throwable e) {
 		log(new Status(IStatus.ERROR, getPluginId(), INTERNAL_ERROR, CompareMessages.getString("ComparePlugin.internal_error"), e)); //$NON-NLS-1$
 	}
@@ -1094,13 +1113,4 @@ public final class CompareUIPlugin extends AbstractUIPlugin {
 	public static void log(IStatus status) {
 		getDefault().getLog().log(status);
 	}
-	
-	public static String getPluginId() {
-		return getDefault().getDescriptor().getUniqueIdentifier();
-	}
-
-	public static boolean filter(String name, boolean isFolder, boolean isArchive) {
-		CompareFilter f= getDefault().fFilter;
-		return f.filter(name, isFolder, isArchive);
-	}
 }
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/ResourceCompareInput.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/ResourceCompareInput.java
index fc76172f1..e26156dd8 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/ResourceCompareInput.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/ResourceCompareInput.java
@@ -86,7 +86,7 @@ class ResourceCompareInput extends CompareEditorInput {
 		}
 		protected IStructureComparator createChild(IResource child) {
 			String name= child.getName();
-			if (CompareUIPlugin.filter(name, child instanceof IContainer, false))
+			if (CompareUIPlugin.getDefault().filter(name, child instanceof IContainer, false))
 				return null;
 			return new FilteredBufferedResourceNode(child);
 		}
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/Utilities.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/Utilities.java
index d99e9204b..99089d379 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/Utilities.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/Utilities.java
@@ -37,6 +37,7 @@ import org.eclipse.core.runtime.Status;
 import org.eclipse.ui.*;
 
 import org.eclipse.compare.CompareConfiguration;
+import org.eclipse.compare.CompareUI;
 import org.eclipse.compare.IEncodedStreamContentAccessor;
 import org.eclipse.compare.IStreamContentAccessor;
 
@@ -287,7 +288,7 @@ public class Utilities {
 	
 	public static String getString(String key) {
 		try {
-			return CompareUIPlugin.getResourceBundle().getString(key);
+			return CompareUI.getResourceBundle().getString(key);
 		} catch (MissingResourceException e) {
 			return "!" + key + "!";//$NON-NLS-2$ //$NON-NLS-1$
 		}
@@ -295,7 +296,7 @@ public class Utilities {
 	
 	public static String getFormattedString(String key, String arg) {
 		try{
-			return MessageFormat.format(CompareUIPlugin.getResourceBundle().getString(key), new String[] { arg });
+			return MessageFormat.format(CompareUI.getResourceBundle().getString(key), new String[] { arg });
 		} catch (MissingResourceException e) {
 			return "!" + key + "!";//$NON-NLS-2$ //$NON-NLS-1$
 		}	
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.properties b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.properties
index e7e6a6c21..80578f06a 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.properties
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.properties
@@ -27,11 +27,15 @@ contentViewers= Content Viewer
 # CompareUIPlugin
 #
 CompareUIPlugin.dialogTitle=Compare
-CompareUIPlugin.noActiveWorkbenchPage=Can't find active workbench page
+CompareUIPlugin.noActiveWorkbenchPage=Can''t find active workbench page
 CompareUIPlugin.compareFailed=Compare Failed
 CompareUIPlugin.openEditorError=Problems Opening Editor
 CompareUIPlugin.noDifferences=There are no differences between the selected inputs.
 
+CompareUIPlugin.targetIdAttributeMissing=target id attribut ''{0}'' missing
+CompareUIPlugin.contentTypeNotFound=content type ''{0}'' not found
+CompareUIPlugin.targetNotFound=target ''{0}'' not found
+
 #
 # Compare Editor
 #
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.xml b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.xml
index d9c32a910..f16f25aa2 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.xml
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.xml
@@ -366,12 +366,4 @@
 	  </contentTypeBinding>
    </extension>
 
-
-	<extension point="org.eclipse.core.runtime.contentTypes">
-		<content-type id="foo" name="Foo Type" 	
-			base-type="org.eclipse.core.runtime.javaProperties"
-			file-extensions="foo"
-		/>
-	</extension>		 
-
 </plugin>