NEW - bug 239959: Adding content to "Compare with other resource" dialog by drag&dropping

https://bugs.eclipse.org/bugs/show_bug.cgi?id=239959

16 files changed, 1290 insertions, 40 deletions

diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareAction.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareAction.java
index 839f003ae..598818fea 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareAction.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareAction.java
@@ -19,6 +19,7 @@ import org.eclipse.ui.IWorkbenchPage;
 import org.eclipse.ui.IWorkbenchPart;
 import org.eclipse.compare.CompareConfiguration;
 import org.eclipse.compare.CompareUI;
+import org.eclipse.core.resources.IResource;
 
 
 /*
@@ -26,17 +27,31 @@ import org.eclipse.compare.CompareUI;
  */
 public class CompareAction extends BaseCompareAction implements IObjectActionDelegate {
 
-	private ResourceCompareInput fInput;
-	private IWorkbenchPage fWorkbenchPage;
-
+	private static ResourceCompareInput fInput;
+	private static IWorkbenchPage fWorkbenchPage;
 
 	public void run(ISelection selection) {
 		if (fInput != null) {
 			// Pass the shell so setSelection can prompt the user for which
 			// resource should be the ancestor
-			boolean ok = fInput.setSelection(selection,
-				fWorkbenchPage.getWorkbenchWindow().getShell());
-			if (!ok) return;
+			boolean ok = fInput.setSelection(selection, fWorkbenchPage
+					.getWorkbenchWindow().getShell());
+			if (!ok)
+				return;
+			fInput.initializeCompareConfiguration();
+			CompareUI.openCompareEditorOnPage(fInput, fWorkbenchPage);
+			fInput = null; // don't reuse this input!
+		}
+	}
+
+	public static void run(IResource[] resources) {
+		fWorkbenchPage = CompareUIPlugin.getActiveWorkbench()
+				.getActiveWorkbenchWindow().getActivePage();
+		if (fInput != null) {
+			boolean ok = fInput.setSelection(resources, fWorkbenchPage
+					.getWorkbenchWindow().getShell());
+			if (!ok)
+				return;
 			fInput.initializeCompareConfiguration();
 			CompareUI.openCompareEditorOnPage(fInput, fWorkbenchPage);
 			fInput= null;	// don't reuse this input!
@@ -58,6 +73,16 @@ public class CompareAction extends BaseCompareAction implements IObjectActionDel
 		return fInput.isEnabled(selection);
 	}
 
+	public static boolean isEnabled(IResource[] resources) {
+		if (fInput == null) {
+			CompareConfiguration cc = new CompareConfiguration();
+			cc.setProperty(CompareEditor.CONFIRM_SAVE_PROPERTY, new Boolean(
+					false));
+			fInput = new ResourceCompareInput(cc);
+		}
+		return fInput.isEnabled(resources);
+	}
+
 	public void setActivePart(IAction action, IWorkbenchPart targetPart) {
 		fWorkbenchPage= targetPart.getSite().getPage();
 	}
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.java
index 800ea1820..49c15408f 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.java
@@ -108,6 +108,16 @@ public final class CompareMessages extends NLS {
 	public static String SelectAncestorDialog_title;
 	public static String SelectAncestorDialog_message;
 	public static String SelectAncestorDialog_option;
+	public static String CompareWithOther_fileLabel;
+	public static String CompareWithOther_ancestor;
+	public static String CompareWithOther_rightPanel;
+	public static String CompareWithOther_leftPanel;
+	public static String CompareWithOther_dialogTitle;
+	public static String CompareWithOther_dialogMessage;
+	public static String CompareWithOther_error_not_comparable;
+	public static String CompareWithOther_error_empty;
+	public static String CompareWithOther_clearAll;
+	public static String CompareWithOther_clear;
 
 	static {
 		NLS.initializeMessages(BUNDLE_NAME, CompareMessages.class);
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.properties b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.properties
index 08a678b6a..b100020b5 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.properties
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.properties
@@ -119,3 +119,14 @@ SelectAncestorDialog_title=Select Common Ancestor
 SelectAncestorDialog_message=Which resource would you like to use as the common ancestor in the three-way compare?
 SelectAncestorDialog_option=''{0}''
 ShowWhitespaceAction_0=Show &Whitespace Characters
+
+CompareWithOther_fileLabel=File:
+CompareWithOther_ancestor=Ancestor
+CompareWithOther_rightPanel=Right panel
+CompareWithOther_leftPanel=Left panel
+CompareWithOther_dialogTitle=Compare with Other Resource...
+CompareWithOther_dialogMessage=Select resources to compare
+CompareWithOther_error_not_comparable=Selected resources are not comparable.
+CompareWithOther_error_empty=Both left and right panel must not be empty.
+CompareWithOther_clearAll=Clear All
+CompareWithOther_clear=Clear
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceAction.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceAction.java
new file mode 100644
index 000000000..f48404afd
--- /dev/null
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceAction.java
@@ -0,0 +1,46 @@
+/*******************************************************************************
+ * Copyright (c) 2008 Aleksandra Wozniak and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Aleksandra Wozniak (aleksandra.k.wozniak@gmail.com) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.compare.internal;
+
+import org.eclipse.jface.action.IAction;
+import org.eclipse.jface.viewers.ISelection;
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.ui.IObjectActionDelegate;
+import org.eclipse.ui.IWorkbenchPart;
+import org.eclipse.ui.PlatformUI;
+
+/**
+ * The "Compare with other resource" action
+ * @since 3.4
+ */
+public class CompareWithOtherResourceAction implements IObjectActionDelegate {
+
+	Shell shell;
+	CompareWithOtherResourceDialog dialog;
+	private ISelection fselection;
+
+	public CompareWithOtherResourceAction() {
+		shell = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getShell();
+	}
+
+	public void setActivePart(IAction action, IWorkbenchPart targetPart) {
+	}
+
+	public void run(IAction action) {
+		dialog = new CompareWithOtherResourceDialog(shell, fselection);
+		dialog.open();
+	}
+
+	public void selectionChanged(IAction action, ISelection selection) {
+		fselection = selection;
+	}
+
+}
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceDialog.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceDialog.java
new file mode 100644
index 000000000..879926d3a
--- /dev/null
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceDialog.java
@@ -0,0 +1,514 @@
+/*******************************************************************************
+ * Copyright (c) 2008 Aleksandra Wozniak and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Aleksandra Wozniak (aleksandra.k.wozniak@gmail.com) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.compare.internal;
+
+import org.eclipse.compare.CompareConfiguration;
+import org.eclipse.core.resources.IResource;
+import org.eclipse.core.resources.IWorkspaceRoot;
+import org.eclipse.core.resources.ResourcesPlugin;
+import org.eclipse.jface.dialogs.IDialogConstants;
+import org.eclipse.jface.dialogs.IMessageProvider;
+import org.eclipse.jface.dialogs.TitleAreaDialog;
+import org.eclipse.jface.viewers.ISelection;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.dnd.DND;
+import org.eclipse.swt.dnd.DragSource;
+import org.eclipse.swt.dnd.DragSourceEvent;
+import org.eclipse.swt.dnd.DragSourceListener;
+import org.eclipse.swt.dnd.DropTarget;
+import org.eclipse.swt.dnd.DropTargetEvent;
+import org.eclipse.swt.dnd.DropTargetListener;
+import org.eclipse.swt.dnd.TextTransfer;
+import org.eclipse.swt.dnd.Transfer;
+import org.eclipse.swt.events.ModifyEvent;
+import org.eclipse.swt.events.ModifyListener;
+import org.eclipse.swt.events.SelectionEvent;
+import org.eclipse.swt.events.SelectionListener;
+import org.eclipse.swt.layout.GridData;
+import org.eclipse.swt.layout.GridLayout;
+import org.eclipse.swt.widgets.Button;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Control;
+import org.eclipse.swt.widgets.Group;
+import org.eclipse.swt.widgets.Label;
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.swt.widgets.Text;
+import org.eclipse.ui.forms.events.ExpansionAdapter;
+import org.eclipse.ui.forms.events.ExpansionEvent;
+import org.eclipse.ui.forms.widgets.ExpandableComposite;
+import org.eclipse.ui.part.ResourceTransfer;
+
+/**
+ * This is a dialog that can invoke the compare editor on chosen files.
+ * <p>
+ * This class can be used as is or can be subclassed.
+ * 
+ * @since 3.4
+ */
+public class CompareWithOtherResourceDialog extends TitleAreaDialog {
+
+	public int CLEAR_RETURN_CODE = 150; // any number != 0
+
+	private class FileTextDragListener implements DragSourceListener {
+
+		private InternalSection section;
+
+		public FileTextDragListener(InternalSection section) {
+			this.section = section;
+		}
+
+		public void dragFinished(DragSourceEvent event) {
+			section.fileText.setText(""); //$NON-NLS-1$
+		}
+
+		public void dragSetData(DragSourceEvent event) {
+			if (TextTransfer.getInstance().isSupportedType(event.dataType))
+				event.data = section.fileText.getText();
+		}
+
+		public void dragStart(DragSourceEvent event) {
+			if (section.fileText.getText() == null)
+				event.doit = false;
+		}
+	}
+
+	private class FileTextDropListener implements DropTargetListener {
+
+		private InternalSection section;
+		private ResourceTransfer resourceTransfer;
+		private TextTransfer textTransfer;
+
+		public FileTextDropListener(InternalSection section) {
+			this.section = section;
+			resourceTransfer = ResourceTransfer.getInstance();
+			textTransfer = TextTransfer.getInstance();
+		}
+
+		public void dragEnter(DropTargetEvent event) {
+			if (event.detail == DND.DROP_DEFAULT) {
+				if ((event.operations & DND.DROP_COPY) != 0)
+					event.detail = DND.DROP_COPY;
+				else
+					event.detail = DND.DROP_NONE;
+			}
+			for (int i = 0; i < event.dataTypes.length; i++) {
+				if (resourceTransfer.isSupportedType(event.dataTypes[i])) {
+					event.currentDataType = event.dataTypes[i];
+					if (event.detail != DND.DROP_COPY)
+						event.detail = DND.DROP_NONE;
+				}
+				break;
+			}
+		}
+
+		public void dragLeave(DropTargetEvent event) {
+		}
+
+		public void dragOperationChanged(DropTargetEvent event) {
+			if (event.detail == DND.DROP_DEFAULT) {
+				if ((event.operations & DND.DROP_COPY) != 0)
+					event.detail = DND.DROP_COPY;
+				else
+					event.detail = DND.DROP_NONE;
+			}
+			if (resourceTransfer.isSupportedType(event.currentDataType)) {
+				if (event.detail != DND.DROP_COPY)
+					event.detail = DND.DROP_NONE;
+			}
+		}
+
+		public void dragOver(DropTargetEvent event) {
+		}
+
+		public void drop(DropTargetEvent event) {
+			if (textTransfer.isSupportedType(event.currentDataType)) {
+				String txt = (String) event.data;
+				section.fileText.setText(txt);
+				section.setResource(ResourcesPlugin.getWorkspace().getRoot()
+						.findMember(txt));
+			}
+			if (resourceTransfer.isSupportedType(event.currentDataType)) {
+				IResource[] files = (IResource[]) event.data;
+				section.setResource(files[0]);
+				section.fileText.setText(section.getResource().getFullPath()
+						.toString());
+			}
+		}
+
+		public void dropAccept(DropTargetEvent event) {
+		}
+
+	}
+
+	private abstract class InternalSection {
+
+		protected Text fileText;
+		protected IResource resource;
+		protected IResource[] files;
+		protected String fileString = null;
+		protected Group group;
+		protected Button clearButton;
+
+		public InternalSection(Composite parent) {
+			createContents(parent);
+		}
+
+		public InternalSection() {
+		}
+
+		public void createContents(Composite parent) {
+		}
+
+		public IResource getResource() {
+			if (resource == null) {
+				if (fileString != null) { //$NON-NLS-1$
+					IWorkspaceRoot root = ResourcesPlugin.getWorkspace()
+							.getRoot();
+					resource = root.findMember(fileString);
+					if (resource instanceof IWorkspaceRoot)
+						return null;
+					return resource;
+				}
+			}
+			return resource;
+		}
+
+		public void setResource(IResource resource) {
+			this.resource = resource;
+			fileText.setText(resource.getFullPath().toString());
+		}
+
+		protected void clearResource() {
+			resource = null;
+			fileText.setText(""); //$NON-NLS-1$
+		}
+
+		protected void initDrag() {
+			DragSource source = new DragSource(fileText, DND.DROP_MOVE
+					| DND.DROP_COPY);
+			Transfer[] types = new Transfer[] { TextTransfer.getInstance(),
+					ResourceTransfer.getInstance() };
+			source.setTransfer(types);
+			source.addDragListener(new FileTextDragListener(this));
+		}
+
+		protected void initDrop() {
+			DropTarget target = new DropTarget(fileText, DND.DROP_MOVE
+					| DND.DROP_COPY | DND.DROP_DEFAULT);
+			final TextTransfer textTransfer = TextTransfer.getInstance();
+			final ResourceTransfer resourceTransfer = ResourceTransfer
+					.getInstance();
+			Transfer[] types = new Transfer[] { textTransfer, resourceTransfer };
+			target.setTransfer(types);
+			target.addDropListener(new FileTextDropListener(this));
+		}
+
+		protected void createGroup(Composite parent) {
+			GridLayout layout = new GridLayout();
+			layout.numColumns = 3;
+			group = new Group(parent, SWT.NONE);
+			group.setLayout(layout);
+			GridData gridData = new GridData();
+			gridData.grabExcessHorizontalSpace = true;
+			gridData.grabExcessVerticalSpace = true;
+			group.setLayoutData(gridData);
+		}
+
+		protected void createFileText() {
+			fileText = new Text(group, SWT.SINGLE | SWT.BORDER);
+			fileText.addModifyListener(new ModifyListener() {
+
+				public void modifyText(ModifyEvent e) {
+					if (files != null)
+						resource = files[0];
+					fileString = fileText.getText();
+					if (fileString == "") //$NON-NLS-1$
+						resource = null;
+					else
+						resource = getResource();
+					if (okButton != null)
+						okButton.setEnabled(comparePossible());
+					updateErrorInfo();
+				}
+
+			});
+
+			GridData textData = new GridData();
+			textData.grabExcessHorizontalSpace = true;
+			textData.horizontalAlignment = SWT.FILL;
+			fileText.setLayoutData(textData);
+		}
+
+		protected void createFileLabel() {
+			final Label fileLabel = new Label(group, SWT.NONE);
+			fileLabel.setText(CompareMessages.CompareWithOther_fileLabel);
+		}
+
+		protected void createClearButton(Composite parent) {
+			clearButton = createButton(parent, CLEAR_RETURN_CODE,
+					CompareMessages.CompareWithOther_clear, false);
+			clearButton.addSelectionListener(new SelectionListener() {
+
+				public void widgetDefaultSelected(SelectionEvent e) {
+					widgetSelected(e);
+				}
+
+				public void widgetSelected(SelectionEvent e) {
+					clearResource();
+				}
+
+			});
+		}
+
+		abstract public void setLayoutData(GridData layoutData);
+
+		abstract public void setText(String text);
+
+	}
+
+	private class InternalGroup extends InternalSection {
+
+		public InternalGroup(Composite parent) {
+			super();
+			createContents(parent);
+		}
+
+		public void createContents(Composite parent) {
+			createGroup(parent);
+			createFileLabel();
+			createFileText();
+			createClearButton(group);
+			initDrag();
+			initDrop();
+		}
+
+		public void setText(String text) {
+			group.setText(text);
+		}
+
+		public void setLayoutData(GridData layoutData) {
+			group.setLayoutData(layoutData);
+		}
+	}
+
+	private class InternalExpandable extends InternalSection {
+
+		private ExpandableComposite expandable;
+
+		public InternalExpandable(Composite parent) {
+			super();
+			createContents(parent);
+		}
+
+		public void createContents(Composite parent) {
+
+			final Composite p = parent;
+
+			expandable = new ExpandableComposite(parent, SWT.NONE,
+					ExpandableComposite.TREE_NODE | ExpandableComposite.TWISTIE);
+
+			createGroup(expandable);
+			expandable.setClient(group);
+			expandable.addExpansionListener(new ExpansionAdapter() {
+				public void expansionStateChanged(ExpansionEvent e) {
+					p.getShell().pack();
+				}
+			});
+
+			createFileLabel();
+			createFileText();
+			createClearButton(group);
+			initDrag();
+			initDrop();
+		}
+
+		public void setText(String text) {
+			expandable.setText(text);
+			group.setText(text);
+		}
+
+		public void setLayoutData(GridData layoutData) {
+			expandable.setLayoutData(layoutData);
+		}
+
+	}
+
+	private Button okButton, cancelButton, clearAllButton;
+	private InternalGroup rightPanel, leftPanel;
+	private InternalExpandable ancestorPanel;
+	private ISelection fselection;
+
+	/**
+	 * Creates the dialog.
+	 * 
+	 * @param shell
+	 *            a shell
+	 * @param selection
+	 *            if the selection is not null, it will be set as initial files
+	 *            for comparison
+	 * @since 3.4
+	 */
+	protected CompareWithOtherResourceDialog(Shell shell, ISelection selection) {
+		super(shell);
+		setShellStyle(SWT.MODELESS | SWT.RESIZE | SWT.MAX);
+		fselection = selection;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * org.eclipse.jface.dialogs.Dialog#createDialogArea(org.eclipse.swt.widgets
+	 * .Composite)
+	 */
+	protected Control createDialogArea(Composite parent) {
+
+		Composite mainPanel = new Composite(parent, SWT.NULL);
+		GridLayout layout = new GridLayout();
+		layout.numColumns = 2;
+		layout.makeColumnsEqualWidth = true;
+		mainPanel.setLayout(layout);
+		mainPanel.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+
+		ancestorPanel = new InternalExpandable(mainPanel);
+		ancestorPanel.setText(CompareMessages.CompareWithOther_ancestor);
+		GridData ancestorGD = new GridData(SWT.FILL, SWT.FILL, true, true);
+		ancestorGD.horizontalSpan = 2;
+		ancestorPanel.setLayoutData(ancestorGD);
+
+		rightPanel = new InternalGroup(mainPanel);
+		rightPanel.setText(CompareMessages.CompareWithOther_rightPanel);
+		GridData rightGD = new GridData(SWT.FILL, SWT.FILL, true, true);
+		rightPanel.setLayoutData(rightGD);
+
+		leftPanel = new InternalGroup(mainPanel);
+		leftPanel.setText(CompareMessages.CompareWithOther_leftPanel);
+		GridData leftGD = new GridData(SWT.FILL, SWT.FILL, true, true);
+		leftPanel.setLayoutData(leftGD);
+
+		setSelection(fselection);
+		getShell().setText(CompareMessages.CompareWithOther_dialogTitle);
+		setTitle(CompareMessages.CompareWithOther_dialogMessage);
+
+		return mainPanel;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * org.eclipse.jface.dialogs.Dialog#createButtonsForButtonBar(org.eclipse
+	 * .swt.widgets.Composite)
+	 */
+	protected void createButtonsForButtonBar(Composite parent) {
+		okButton = createButton(parent, OK, IDialogConstants.OK_LABEL, false);
+		okButton.addSelectionListener(new SelectionListener() {
+
+			public void widgetDefaultSelected(SelectionEvent e) {
+				widgetSelected(e);
+			}
+
+			public void widgetSelected(SelectionEvent e) {
+
+				IResource[] resources;
+
+				IResource rightResource = rightPanel.getResource();
+				IResource leftResource = leftPanel.getResource();
+				IResource ancestorResource = ancestorPanel.getResource();
+				if (ancestorResource == null)
+					resources = new IResource[] { leftResource, rightResource };
+				else
+					resources = new IResource[] { ancestorResource,
+							leftResource, rightResource };
+
+				if (CompareAction.isEnabled(resources))
+					CompareAction.run(resources);
+			}
+
+		});
+		okButton.setEnabled(comparePossible());
+
+		cancelButton = createButton(parent, CANCEL,
+				IDialogConstants.CANCEL_LABEL, true);
+		cancelButton.addSelectionListener(new SelectionListener() {
+
+			public void widgetDefaultSelected(SelectionEvent e) {
+				widgetSelected(e);
+			}
+
+			public void widgetSelected(SelectionEvent e) {
+			}
+
+		});
+
+		clearAllButton = createButton(parent, CLEAR_RETURN_CODE,
+				CompareMessages.CompareWithOther_clearAll, false);
+		clearAllButton.addSelectionListener(new SelectionListener() {
+
+			public void widgetDefaultSelected(SelectionEvent e) {
+				widgetSelected(e);
+			}
+
+			public void widgetSelected(SelectionEvent e) {
+				leftPanel.clearResource();
+				rightPanel.clearResource();
+				ancestorPanel.clearResource();
+			}
+
+		});
+	}
+
+	private void setSelection(ISelection selection) {
+		IResource[] selectedResources = Utilities.getResources(selection);
+		switch (selectedResources.length) {
+		case 0:
+			break;
+		case 1:
+			leftPanel.setResource(selectedResources[0]);
+			break;
+		case 2:
+			leftPanel.setResource(selectedResources[0]);
+			rightPanel.setResource(selectedResources[1]);
+			break;
+		case 3:
+			ancestorPanel.setResource(selectedResources[0]);
+			ancestorPanel.expandable.setExpanded(true);
+			leftPanel.setResource(selectedResources[1]);
+			rightPanel.setResource(selectedResources[2]);
+			break;
+		}
+	}
+
+	private boolean comparePossible() {
+		IResource[] resources;
+		if (ancestorPanel.resource == null)
+			resources = new IResource[] { leftPanel.resource,
+					rightPanel.resource };
+		else
+			resources = new IResource[] { ancestorPanel.resource,
+					leftPanel.resource, rightPanel.resource };
+
+		ResourceCompareInput r = new ResourceCompareInput(
+				new CompareConfiguration());
+		return r.isEnabled(resources);
+	}
+
+	private void updateErrorInfo() {
+		if (leftPanel.resource == null || rightPanel.resource == null)
+			setMessage(CompareMessages.CompareWithOther_error_empty,
+					IMessageProvider.ERROR);
+		else if (!comparePossible())
+			setMessage(CompareMessages.CompareWithOther_error_not_comparable,
+					IMessageProvider.ERROR);
+		else
+			setMessage(null);
+	}
+}
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 fcacd04f4..e534fa5a0 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
@@ -201,11 +201,14 @@ class ResourceCompareInput extends CompareEditorInput {
 	// to use as the ancestor.  Returns false if the user cancels the prompt,
 	// true otherwise.
 	boolean setSelection(ISelection s, Shell shell) {
-		
-		IResource[] selection= Utilities.getResources(s);
+		IResource[] selection = Utilities.getResources(s);
+		return setSelection(selection, shell);
+	}
+
+	boolean setSelection(IResource[] selection, Shell shell) {
+
+		fThreeWay = selection.length == 3;
 
-		fThreeWay= selection.length == 3;
-		
 		if (fThreeWay) {
 			SelectAncestorDialog dialog =
 				new SelectAncestorDialog(shell, selection);
@@ -233,21 +236,26 @@ class ResourceCompareInput extends CompareEditorInput {
 	 * Returns true if compare can be executed for the given selection.
 	 */
 	public boolean isEnabled(ISelection s) {
-		
-		IResource[] selection= Utilities.getResources(s);
-		if (selection.length < 2 || selection.length > 3)
+
+		IResource[] selection = Utilities.getResources(s);
+		return isEnabled(selection);
+	}
+
+	public boolean isEnabled(IResource[] resources) {
+		if (resources.length < 2 || resources.length > 3)
 			return false;
 
-		boolean threeWay= selection.length == 3;
+		boolean threeWay= resources.length == 3;
 		
-		if (threeWay)
+		if (threeWay) {
 			// It only makes sense if they're all mutually comparable.
 			// If not, the user should compare two of them.
-			return comparable(selection[0], selection[1])
-				&& comparable(selection[0], selection[2])
-				&& comparable(selection[1], selection[2]);
-		
-		return comparable(selection[0], selection[1]);
+			return comparable(resources[0], resources[1])
+					&& comparable(resources[0], resources[2])
+					&& comparable(resources[1], resources[2]);
+		}
+
+		return comparable(resources[0], resources[1]);
 	}
 	
 	/**
diff --git a/bundles/org.eclipse.compare/plugin.properties b/bundles/org.eclipse.compare/plugin.properties
index c00338667..be271000e 100644
--- a/bundles/org.eclipse.compare/plugin.properties
+++ b/bundles/org.eclipse.compare/plugin.properties
@@ -83,6 +83,9 @@ CompareWithMenu.label= Comp&are With
 CompareWithEachOtherAction.label= &Each Other
 CompareWithEachOtherAction.tooltip= Compare the Selected Resources
 
+CompareWithOtherResource.label= &Other Resource
+CompareWithOtherResource.tooltip= Open the 'Compare With' Dialog
+
 CompareWithHistoryAction.label= &Local History...
 CompareWithHistoryAction.tooltip= Compare the Selected Resource with Local History
 
diff --git a/bundles/org.eclipse.compare/plugin.xml b/bundles/org.eclipse.compare/plugin.xml
index 0a0ab38ca..c0b472075 100644
--- a/bundles/org.eclipse.compare/plugin.xml
+++ b/bundles/org.eclipse.compare/plugin.xml
@@ -201,6 +201,14 @@
                enablesFor="2+"
                id="compareWithEachOther">
          </action>
+         <action
+               class="org.eclipse.compare.internal.CompareWithOtherResourceAction"
+               enablesFor="1"
+               id="compareWithOtherResource"
+               label="%CompareWithOtherResource.label"
+               menubarPath="compareWithMenu/compareWithGroup"
+               tooltip="%CompareWithOtherResourceAction.tooltip">
+         </action>
       </objectContribution>
       <objectContribution
             objectClass="org.eclipse.core.resources.IFile"
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareAction.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareAction.java
index 839f003ae..598818fea 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareAction.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareAction.java
@@ -19,6 +19,7 @@ import org.eclipse.ui.IWorkbenchPage;
 import org.eclipse.ui.IWorkbenchPart;
 import org.eclipse.compare.CompareConfiguration;
 import org.eclipse.compare.CompareUI;
+import org.eclipse.core.resources.IResource;
 
 
 /*
@@ -26,17 +27,31 @@ import org.eclipse.compare.CompareUI;
  */
 public class CompareAction extends BaseCompareAction implements IObjectActionDelegate {
 
-	private ResourceCompareInput fInput;
-	private IWorkbenchPage fWorkbenchPage;
-
+	private static ResourceCompareInput fInput;
+	private static IWorkbenchPage fWorkbenchPage;
 
 	public void run(ISelection selection) {
 		if (fInput != null) {
 			// Pass the shell so setSelection can prompt the user for which
 			// resource should be the ancestor
-			boolean ok = fInput.setSelection(selection,
-				fWorkbenchPage.getWorkbenchWindow().getShell());
-			if (!ok) return;
+			boolean ok = fInput.setSelection(selection, fWorkbenchPage
+					.getWorkbenchWindow().getShell());
+			if (!ok)
+				return;
+			fInput.initializeCompareConfiguration();
+			CompareUI.openCompareEditorOnPage(fInput, fWorkbenchPage);
+			fInput = null; // don't reuse this input!
+		}
+	}
+
+	public static void run(IResource[] resources) {
+		fWorkbenchPage = CompareUIPlugin.getActiveWorkbench()
+				.getActiveWorkbenchWindow().getActivePage();
+		if (fInput != null) {
+			boolean ok = fInput.setSelection(resources, fWorkbenchPage
+					.getWorkbenchWindow().getShell());
+			if (!ok)
+				return;
 			fInput.initializeCompareConfiguration();
 			CompareUI.openCompareEditorOnPage(fInput, fWorkbenchPage);
 			fInput= null;	// don't reuse this input!
@@ -58,6 +73,16 @@ public class CompareAction extends BaseCompareAction implements IObjectActionDel
 		return fInput.isEnabled(selection);
 	}
 
+	public static boolean isEnabled(IResource[] resources) {
+		if (fInput == null) {
+			CompareConfiguration cc = new CompareConfiguration();
+			cc.setProperty(CompareEditor.CONFIRM_SAVE_PROPERTY, new Boolean(
+					false));
+			fInput = new ResourceCompareInput(cc);
+		}
+		return fInput.isEnabled(resources);
+	}
+
 	public void setActivePart(IAction action, IWorkbenchPart targetPart) {
 		fWorkbenchPage= targetPart.getSite().getPage();
 	}
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.java
index 800ea1820..49c15408f 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.java
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.java
@@ -108,6 +108,16 @@ public final class CompareMessages extends NLS {
 	public static String SelectAncestorDialog_title;
 	public static String SelectAncestorDialog_message;
 	public static String SelectAncestorDialog_option;
+	public static String CompareWithOther_fileLabel;
+	public static String CompareWithOther_ancestor;
+	public static String CompareWithOther_rightPanel;
+	public static String CompareWithOther_leftPanel;
+	public static String CompareWithOther_dialogTitle;
+	public static String CompareWithOther_dialogMessage;
+	public static String CompareWithOther_error_not_comparable;
+	public static String CompareWithOther_error_empty;
+	public static String CompareWithOther_clearAll;
+	public static String CompareWithOther_clear;
 
 	static {
 		NLS.initializeMessages(BUNDLE_NAME, CompareMessages.class);
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.properties b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.properties
index 08a678b6a..b100020b5 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.properties
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.properties
@@ -119,3 +119,14 @@ SelectAncestorDialog_title=Select Common Ancestor
 SelectAncestorDialog_message=Which resource would you like to use as the common ancestor in the three-way compare?
 SelectAncestorDialog_option=''{0}''
 ShowWhitespaceAction_0=Show &Whitespace Characters
+
+CompareWithOther_fileLabel=File:
+CompareWithOther_ancestor=Ancestor
+CompareWithOther_rightPanel=Right panel
+CompareWithOther_leftPanel=Left panel
+CompareWithOther_dialogTitle=Compare with Other Resource...
+CompareWithOther_dialogMessage=Select resources to compare
+CompareWithOther_error_not_comparable=Selected resources are not comparable.
+CompareWithOther_error_empty=Both left and right panel must not be empty.
+CompareWithOther_clearAll=Clear All
+CompareWithOther_clear=Clear
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceAction.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceAction.java
new file mode 100644
index 000000000..f48404afd
--- /dev/null
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceAction.java
@@ -0,0 +1,46 @@
+/*******************************************************************************
+ * Copyright (c) 2008 Aleksandra Wozniak and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Aleksandra Wozniak (aleksandra.k.wozniak@gmail.com) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.compare.internal;
+
+import org.eclipse.jface.action.IAction;
+import org.eclipse.jface.viewers.ISelection;
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.ui.IObjectActionDelegate;
+import org.eclipse.ui.IWorkbenchPart;
+import org.eclipse.ui.PlatformUI;
+
+/**
+ * The "Compare with other resource" action
+ * @since 3.4
+ */
+public class CompareWithOtherResourceAction implements IObjectActionDelegate {
+
+	Shell shell;
+	CompareWithOtherResourceDialog dialog;
+	private ISelection fselection;
+
+	public CompareWithOtherResourceAction() {
+		shell = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getShell();
+	}
+
+	public void setActivePart(IAction action, IWorkbenchPart targetPart) {
+	}
+
+	public void run(IAction action) {
+		dialog = new CompareWithOtherResourceDialog(shell, fselection);
+		dialog.open();
+	}
+
+	public void selectionChanged(IAction action, ISelection selection) {
+		fselection = selection;
+	}
+
+}
diff --git a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceDialog.java b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceDialog.java
new file mode 100644
index 000000000..879926d3a
--- /dev/null
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareWithOtherResourceDialog.java
@@ -0,0 +1,514 @@
+/*******************************************************************************
+ * Copyright (c) 2008 Aleksandra Wozniak and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Aleksandra Wozniak (aleksandra.k.wozniak@gmail.com) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.compare.internal;
+
+import org.eclipse.compare.CompareConfiguration;
+import org.eclipse.core.resources.IResource;
+import org.eclipse.core.resources.IWorkspaceRoot;
+import org.eclipse.core.resources.ResourcesPlugin;
+import org.eclipse.jface.dialogs.IDialogConstants;
+import org.eclipse.jface.dialogs.IMessageProvider;
+import org.eclipse.jface.dialogs.TitleAreaDialog;
+import org.eclipse.jface.viewers.ISelection;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.dnd.DND;
+import org.eclipse.swt.dnd.DragSource;
+import org.eclipse.swt.dnd.DragSourceEvent;
+import org.eclipse.swt.dnd.DragSourceListener;
+import org.eclipse.swt.dnd.DropTarget;
+import org.eclipse.swt.dnd.DropTargetEvent;
+import org.eclipse.swt.dnd.DropTargetListener;
+import org.eclipse.swt.dnd.TextTransfer;
+import org.eclipse.swt.dnd.Transfer;
+import org.eclipse.swt.events.ModifyEvent;
+import org.eclipse.swt.events.ModifyListener;
+import org.eclipse.swt.events.SelectionEvent;
+import org.eclipse.swt.events.SelectionListener;
+import org.eclipse.swt.layout.GridData;
+import org.eclipse.swt.layout.GridLayout;
+import org.eclipse.swt.widgets.Button;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Control;
+import org.eclipse.swt.widgets.Group;
+import org.eclipse.swt.widgets.Label;
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.swt.widgets.Text;
+import org.eclipse.ui.forms.events.ExpansionAdapter;
+import org.eclipse.ui.forms.events.ExpansionEvent;
+import org.eclipse.ui.forms.widgets.ExpandableComposite;
+import org.eclipse.ui.part.ResourceTransfer;
+
+/**
+ * This is a dialog that can invoke the compare editor on chosen files.
+ * <p>
+ * This class can be used as is or can be subclassed.
+ * 
+ * @since 3.4
+ */
+public class CompareWithOtherResourceDialog extends TitleAreaDialog {
+
+	public int CLEAR_RETURN_CODE = 150; // any number != 0
+
+	private class FileTextDragListener implements DragSourceListener {
+
+		private InternalSection section;
+
+		public FileTextDragListener(InternalSection section) {
+			this.section = section;
+		}
+
+		public void dragFinished(DragSourceEvent event) {
+			section.fileText.setText(""); //$NON-NLS-1$
+		}
+
+		public void dragSetData(DragSourceEvent event) {
+			if (TextTransfer.getInstance().isSupportedType(event.dataType))
+				event.data = section.fileText.getText();
+		}
+
+		public void dragStart(DragSourceEvent event) {
+			if (section.fileText.getText() == null)
+				event.doit = false;
+		}
+	}
+
+	private class FileTextDropListener implements DropTargetListener {
+
+		private InternalSection section;
+		private ResourceTransfer resourceTransfer;
+		private TextTransfer textTransfer;
+
+		public FileTextDropListener(InternalSection section) {
+			this.section = section;
+			resourceTransfer = ResourceTransfer.getInstance();
+			textTransfer = TextTransfer.getInstance();
+		}
+
+		public void dragEnter(DropTargetEvent event) {
+			if (event.detail == DND.DROP_DEFAULT) {
+				if ((event.operations & DND.DROP_COPY) != 0)
+					event.detail = DND.DROP_COPY;
+				else
+					event.detail = DND.DROP_NONE;
+			}
+			for (int i = 0; i < event.dataTypes.length; i++) {
+				if (resourceTransfer.isSupportedType(event.dataTypes[i])) {
+					event.currentDataType = event.dataTypes[i];
+					if (event.detail != DND.DROP_COPY)
+						event.detail = DND.DROP_NONE;
+				}
+				break;
+			}
+		}
+
+		public void dragLeave(DropTargetEvent event) {
+		}
+
+		public void dragOperationChanged(DropTargetEvent event) {
+			if (event.detail == DND.DROP_DEFAULT) {
+				if ((event.operations & DND.DROP_COPY) != 0)
+					event.detail = DND.DROP_COPY;
+				else
+					event.detail = DND.DROP_NONE;
+			}
+			if (resourceTransfer.isSupportedType(event.currentDataType)) {
+				if (event.detail != DND.DROP_COPY)
+					event.detail = DND.DROP_NONE;
+			}
+		}
+
+		public void dragOver(DropTargetEvent event) {
+		}
+
+		public void drop(DropTargetEvent event) {
+			if (textTransfer.isSupportedType(event.currentDataType)) {
+				String txt = (String) event.data;
+				section.fileText.setText(txt);
+				section.setResource(ResourcesPlugin.getWorkspace().getRoot()
+						.findMember(txt));
+			}
+			if (resourceTransfer.isSupportedType(event.currentDataType)) {
+				IResource[] files = (IResource[]) event.data;
+				section.setResource(files[0]);
+				section.fileText.setText(section.getResource().getFullPath()
+						.toString());
+			}
+		}
+
+		public void dropAccept(DropTargetEvent event) {
+		}
+
+	}
+
+	private abstract class InternalSection {
+
+		protected Text fileText;
+		protected IResource resource;
+		protected IResource[] files;
+		protected String fileString = null;
+		protected Group group;
+		protected Button clearButton;
+
+		public InternalSection(Composite parent) {
+			createContents(parent);
+		}
+
+		public InternalSection() {
+		}
+
+		public void createContents(Composite parent) {
+		}
+
+		public IResource getResource() {
+			if (resource == null) {
+				if (fileString != null) { //$NON-NLS-1$
+					IWorkspaceRoot root = ResourcesPlugin.getWorkspace()
+							.getRoot();
+					resource = root.findMember(fileString);
+					if (resource instanceof IWorkspaceRoot)
+						return null;
+					return resource;
+				}
+			}
+			return resource;
+		}
+
+		public void setResource(IResource resource) {
+			this.resource = resource;
+			fileText.setText(resource.getFullPath().toString());
+		}
+
+		protected void clearResource() {
+			resource = null;
+			fileText.setText(""); //$NON-NLS-1$
+		}
+
+		protected void initDrag() {
+			DragSource source = new DragSource(fileText, DND.DROP_MOVE
+					| DND.DROP_COPY);
+			Transfer[] types = new Transfer[] { TextTransfer.getInstance(),
+					ResourceTransfer.getInstance() };
+			source.setTransfer(types);
+			source.addDragListener(new FileTextDragListener(this));
+		}
+
+		protected void initDrop() {
+			DropTarget target = new DropTarget(fileText, DND.DROP_MOVE
+					| DND.DROP_COPY | DND.DROP_DEFAULT);
+			final TextTransfer textTransfer = TextTransfer.getInstance();
+			final ResourceTransfer resourceTransfer = ResourceTransfer
+					.getInstance();
+			Transfer[] types = new Transfer[] { textTransfer, resourceTransfer };
+			target.setTransfer(types);
+			target.addDropListener(new FileTextDropListener(this));
+		}
+
+		protected void createGroup(Composite parent) {
+			GridLayout layout = new GridLayout();
+			layout.numColumns = 3;
+			group = new Group(parent, SWT.NONE);
+			group.setLayout(layout);
+			GridData gridData = new GridData();
+			gridData.grabExcessHorizontalSpace = true;
+			gridData.grabExcessVerticalSpace = true;
+			group.setLayoutData(gridData);
+		}
+
+		protected void createFileText() {
+			fileText = new Text(group, SWT.SINGLE | SWT.BORDER);
+			fileText.addModifyListener(new ModifyListener() {
+
+				public void modifyText(ModifyEvent e) {
+					if (files != null)
+						resource = files[0];
+					fileString = fileText.getText();
+					if (fileString == "") //$NON-NLS-1$
+						resource = null;
+					else
+						resource = getResource();
+					if (okButton != null)
+						okButton.setEnabled(comparePossible());
+					updateErrorInfo();
+				}
+
+			});
+
+			GridData textData = new GridData();
+			textData.grabExcessHorizontalSpace = true;
+			textData.horizontalAlignment = SWT.FILL;
+			fileText.setLayoutData(textData);
+		}
+
+		protected void createFileLabel() {
+			final Label fileLabel = new Label(group, SWT.NONE);
+			fileLabel.setText(CompareMessages.CompareWithOther_fileLabel);
+		}
+
+		protected void createClearButton(Composite parent) {
+			clearButton = createButton(parent, CLEAR_RETURN_CODE,
+					CompareMessages.CompareWithOther_clear, false);
+			clearButton.addSelectionListener(new SelectionListener() {
+
+				public void widgetDefaultSelected(SelectionEvent e) {
+					widgetSelected(e);
+				}
+
+				public void widgetSelected(SelectionEvent e) {
+					clearResource();
+				}
+
+			});
+		}
+
+		abstract public void setLayoutData(GridData layoutData);
+
+		abstract public void setText(String text);
+
+	}
+
+	private class InternalGroup extends InternalSection {
+
+		public InternalGroup(Composite parent) {
+			super();
+			createContents(parent);
+		}
+
+		public void createContents(Composite parent) {
+			createGroup(parent);
+			createFileLabel();
+			createFileText();
+			createClearButton(group);
+			initDrag();
+			initDrop();
+		}
+
+		public void setText(String text) {
+			group.setText(text);
+		}
+
+		public void setLayoutData(GridData layoutData) {
+			group.setLayoutData(layoutData);
+		}
+	}
+
+	private class InternalExpandable extends InternalSection {
+
+		private ExpandableComposite expandable;
+
+		public InternalExpandable(Composite parent) {
+			super();
+			createContents(parent);
+		}
+
+		public void createContents(Composite parent) {
+
+			final Composite p = parent;
+
+			expandable = new ExpandableComposite(parent, SWT.NONE,
+					ExpandableComposite.TREE_NODE | ExpandableComposite.TWISTIE);
+
+			createGroup(expandable);
+			expandable.setClient(group);
+			expandable.addExpansionListener(new ExpansionAdapter() {
+				public void expansionStateChanged(ExpansionEvent e) {
+					p.getShell().pack();
+				}
+			});
+
+			createFileLabel();
+			createFileText();
+			createClearButton(group);
+			initDrag();
+			initDrop();
+		}
+
+		public void setText(String text) {
+			expandable.setText(text);
+			group.setText(text);
+		}
+
+		public void setLayoutData(GridData layoutData) {
+			expandable.setLayoutData(layoutData);
+		}
+
+	}
+
+	private Button okButton, cancelButton, clearAllButton;
+	private InternalGroup rightPanel, leftPanel;
+	private InternalExpandable ancestorPanel;
+	private ISelection fselection;
+
+	/**
+	 * Creates the dialog.
+	 * 
+	 * @param shell
+	 *            a shell
+	 * @param selection
+	 *            if the selection is not null, it will be set as initial files
+	 *            for comparison
+	 * @since 3.4
+	 */
+	protected CompareWithOtherResourceDialog(Shell shell, ISelection selection) {
+		super(shell);
+		setShellStyle(SWT.MODELESS | SWT.RESIZE | SWT.MAX);
+		fselection = selection;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * org.eclipse.jface.dialogs.Dialog#createDialogArea(org.eclipse.swt.widgets
+	 * .Composite)
+	 */
+	protected Control createDialogArea(Composite parent) {
+
+		Composite mainPanel = new Composite(parent, SWT.NULL);
+		GridLayout layout = new GridLayout();
+		layout.numColumns = 2;
+		layout.makeColumnsEqualWidth = true;
+		mainPanel.setLayout(layout);
+		mainPanel.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+
+		ancestorPanel = new InternalExpandable(mainPanel);
+		ancestorPanel.setText(CompareMessages.CompareWithOther_ancestor);
+		GridData ancestorGD = new GridData(SWT.FILL, SWT.FILL, true, true);
+		ancestorGD.horizontalSpan = 2;
+		ancestorPanel.setLayoutData(ancestorGD);
+
+		rightPanel = new InternalGroup(mainPanel);
+		rightPanel.setText(CompareMessages.CompareWithOther_rightPanel);
+		GridData rightGD = new GridData(SWT.FILL, SWT.FILL, true, true);
+		rightPanel.setLayoutData(rightGD);
+
+		leftPanel = new InternalGroup(mainPanel);
+		leftPanel.setText(CompareMessages.CompareWithOther_leftPanel);
+		GridData leftGD = new GridData(SWT.FILL, SWT.FILL, true, true);
+		leftPanel.setLayoutData(leftGD);
+
+		setSelection(fselection);
+		getShell().setText(CompareMessages.CompareWithOther_dialogTitle);
+		setTitle(CompareMessages.CompareWithOther_dialogMessage);
+
+		return mainPanel;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * org.eclipse.jface.dialogs.Dialog#createButtonsForButtonBar(org.eclipse
+	 * .swt.widgets.Composite)
+	 */
+	protected void createButtonsForButtonBar(Composite parent) {
+		okButton = createButton(parent, OK, IDialogConstants.OK_LABEL, false);
+		okButton.addSelectionListener(new SelectionListener() {
+
+			public void widgetDefaultSelected(SelectionEvent e) {
+				widgetSelected(e);
+			}
+
+			public void widgetSelected(SelectionEvent e) {
+
+				IResource[] resources;
+
+				IResource rightResource = rightPanel.getResource();
+				IResource leftResource = leftPanel.getResource();
+				IResource ancestorResource = ancestorPanel.getResource();
+				if (ancestorResource == null)
+					resources = new IResource[] { leftResource, rightResource };
+				else
+					resources = new IResource[] { ancestorResource,
+							leftResource, rightResource };
+
+				if (CompareAction.isEnabled(resources))
+					CompareAction.run(resources);
+			}
+
+		});
+		okButton.setEnabled(comparePossible());
+
+		cancelButton = createButton(parent, CANCEL,
+				IDialogConstants.CANCEL_LABEL, true);
+		cancelButton.addSelectionListener(new SelectionListener() {
+
+			public void widgetDefaultSelected(SelectionEvent e) {
+				widgetSelected(e);
+			}
+
+			public void widgetSelected(SelectionEvent e) {
+			}
+
+		});
+
+		clearAllButton = createButton(parent, CLEAR_RETURN_CODE,
+				CompareMessages.CompareWithOther_clearAll, false);
+		clearAllButton.addSelectionListener(new SelectionListener() {
+
+			public void widgetDefaultSelected(SelectionEvent e) {
+				widgetSelected(e);
+			}
+
+			public void widgetSelected(SelectionEvent e) {
+				leftPanel.clearResource();
+				rightPanel.clearResource();
+				ancestorPanel.clearResource();
+			}
+
+		});
+	}
+
+	private void setSelection(ISelection selection) {
+		IResource[] selectedResources = Utilities.getResources(selection);
+		switch (selectedResources.length) {
+		case 0:
+			break;
+		case 1:
+			leftPanel.setResource(selectedResources[0]);
+			break;
+		case 2:
+			leftPanel.setResource(selectedResources[0]);
+			rightPanel.setResource(selectedResources[1]);
+			break;
+		case 3:
+			ancestorPanel.setResource(selectedResources[0]);
+			ancestorPanel.expandable.setExpanded(true);
+			leftPanel.setResource(selectedResources[1]);
+			rightPanel.setResource(selectedResources[2]);
+			break;
+		}
+	}
+
+	private boolean comparePossible() {
+		IResource[] resources;
+		if (ancestorPanel.resource == null)
+			resources = new IResource[] { leftPanel.resource,
+					rightPanel.resource };
+		else
+			resources = new IResource[] { ancestorPanel.resource,
+					leftPanel.resource, rightPanel.resource };
+
+		ResourceCompareInput r = new ResourceCompareInput(
+				new CompareConfiguration());
+		return r.isEnabled(resources);
+	}
+
+	private void updateErrorInfo() {
+		if (leftPanel.resource == null || rightPanel.resource == null)
+			setMessage(CompareMessages.CompareWithOther_error_empty,
+					IMessageProvider.ERROR);
+		else if (!comparePossible())
+			setMessage(CompareMessages.CompareWithOther_error_not_comparable,
+					IMessageProvider.ERROR);
+		else
+			setMessage(null);
+	}
+}
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 fcacd04f4..e534fa5a0 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
@@ -201,11 +201,14 @@ class ResourceCompareInput extends CompareEditorInput {
 	// to use as the ancestor.  Returns false if the user cancels the prompt,
 	// true otherwise.
 	boolean setSelection(ISelection s, Shell shell) {
-		
-		IResource[] selection= Utilities.getResources(s);
+		IResource[] selection = Utilities.getResources(s);
+		return setSelection(selection, shell);
+	}
+
+	boolean setSelection(IResource[] selection, Shell shell) {
+
+		fThreeWay = selection.length == 3;
 
-		fThreeWay= selection.length == 3;
-		
 		if (fThreeWay) {
 			SelectAncestorDialog dialog =
 				new SelectAncestorDialog(shell, selection);
@@ -233,21 +236,26 @@ class ResourceCompareInput extends CompareEditorInput {
 	 * Returns true if compare can be executed for the given selection.
 	 */
 	public boolean isEnabled(ISelection s) {
-		
-		IResource[] selection= Utilities.getResources(s);
-		if (selection.length < 2 || selection.length > 3)
+
+		IResource[] selection = Utilities.getResources(s);
+		return isEnabled(selection);
+	}
+
+	public boolean isEnabled(IResource[] resources) {
+		if (resources.length < 2 || resources.length > 3)
 			return false;
 
-		boolean threeWay= selection.length == 3;
+		boolean threeWay= resources.length == 3;
 		
-		if (threeWay)
+		if (threeWay) {
 			// It only makes sense if they're all mutually comparable.
 			// If not, the user should compare two of them.
-			return comparable(selection[0], selection[1])
-				&& comparable(selection[0], selection[2])
-				&& comparable(selection[1], selection[2]);
-		
-		return comparable(selection[0], selection[1]);
+			return comparable(resources[0], resources[1])
+					&& comparable(resources[0], resources[2])
+					&& comparable(resources[1], resources[2]);
+		}
+
+		return comparable(resources[0], resources[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 c00338667..be271000e 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.properties
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.properties
@@ -83,6 +83,9 @@ CompareWithMenu.label= Comp&are With
 CompareWithEachOtherAction.label= &Each Other
 CompareWithEachOtherAction.tooltip= Compare the Selected Resources
 
+CompareWithOtherResource.label= &Other Resource
+CompareWithOtherResource.tooltip= Open the 'Compare With' Dialog
+
 CompareWithHistoryAction.label= &Local History...
 CompareWithHistoryAction.tooltip= Compare the Selected Resource with Local History
 
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 0a0ab38ca..c0b472075 100644
--- a/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.xml
+++ b/bundles/org.eclipse.compare/plugins/org.eclipse.compare/plugin.xml
@@ -201,6 +201,14 @@
                enablesFor="2+"
                id="compareWithEachOther">
          </action>
+         <action
+               class="org.eclipse.compare.internal.CompareWithOtherResourceAction"
+               enablesFor="1"
+               id="compareWithOtherResource"
+               label="%CompareWithOtherResource.label"
+               menubarPath="compareWithMenu/compareWithGroup"
+               tooltip="%CompareWithOtherResourceAction.tooltip">
+         </action>
       </objectContribution>
       <objectContribution
             objectClass="org.eclipse.core.resources.IFile"