Bug 84353 [typing] Hippie completion fills undo stack
I20050202-0800 Toggling through the lists adds each item to the undo stack and hence Undo (Ctrl+Z) undoes each by each.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaMoveLinesAction.java
* Indicates whether there are any pending registrations.<br/>
			 * Invariant: <code>fIsInstalled || (fWidgetEventSource == fDocumentEventSource == null)</code>
			 */
			private boolean fIsInstalled;
			
			/**
			 * Installs the exit strategy with all event sources.
			 */
			public void install() {
				if (fIsInstalled)
					uninstall();
				fIsInstalled= true;
				
				ISourceViewer viewer= fEditor.getViewer();
				if (viewer == null)
					return;
				
				fWidgetEventSource= viewer.getTextWidget();
				if (fWidgetEventSource == null)
					return;
				
				fWidgetEventSource.addMouseListener(this);
				fWidgetEventSource.addFocusListener(this);
				
				fDocumentEventSource= viewer.getDocument();
				if (fDocumentEventSource != null)
					fDocumentEventSource.addDocumentListener(this);
				
				fSelectionEventSource= viewer.getSelectionProvider();
				if (fSelectionEventSource != null)