### Eclipse Workspace Patch 1.0
#P org.eclipse.gmf.runtime.diagram.ui
Index: src/org/eclipse/gmf/runtime/diagram/ui/parts/DiagramEditorWithFlyOutPalette.java
===================================================================
RCS file: /cvsroot/technology/org.eclipse.gmf/plugins/org.eclipse.gmf.runtime.diagram.ui/src/org/eclipse/gmf/runtime/diagram/ui/parts/DiagramEditorWithFlyOutPalette.java,v
retrieving revision 1.9
diff -u -r1.9 DiagramEditorWithFlyOutPalette.java
--- src/org/eclipse/gmf/runtime/diagram/ui/parts/DiagramEditorWithFlyOutPalette.java	12 Dec 2005 16:49:28 -0000	1.9
+++ src/org/eclipse/gmf/runtime/diagram/ui/parts/DiagramEditorWithFlyOutPalette.java	22 Mar 2007 12:44:22 -0000
@@ -74,7 +74,7 @@
 	/**
 	 * The activity listener.
 	 */
-	private ActivityManagerListener activityManagerListener;
+	private IActivityManagerListener activityManagerListener;
 
 	boolean fHasFlyoutPalette = true;
 	public DiagramEditorWithFlyOutPalette() {
@@ -571,18 +571,24 @@
 
 	protected void startListening() {
 		super.startListening();
-		activityManagerListener = new ActivityManagerListener();
-		PlatformUI.getWorkbench().getActivitySupport().getActivityManager()
-			.addActivityManagerListener(activityManagerListener);
+		activityManagerListener = createActivityManagerListener();
+		if (activityManagerListener != null) {
+			PlatformUI.getWorkbench().getActivitySupport().getActivityManager()
+				.addActivityManagerListener(activityManagerListener);
+		}
 	}
 
 	protected void stopListening() {
 		if (activityManagerListener != null) {
 			PlatformUI.getWorkbench().getActivitySupport().getActivityManager()
 				.removeActivityManagerListener(activityManagerListener);
+			activityManagerListener = null;
 		}
-		activityManagerListener = null;
 		super.stopListening();
 	}
 	
+    protected IActivityManagerListener createActivityManagerListener() {
+        return new ActivityManagerListener();
+    }
+	
 }