Bug 156865 Undo / Redo marker actions not updated
I20060906-1200 If a file gets delete after adding/changing/removing a marker then the Undo and Redo actions are not updated and still show, e.g. Undo Add Task Redo Add Task Executing the undo or redo does nothing (no feedback, no .log entry) and the undo and redo menu text remains the same and enabled.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/undo/AbstractWorkspaceOperation.java
* that operations can be invalidated if their associated resources change.
	 */
	private void addWorkspaceListener() {
		listener = new IResourceChangeListener() {
			public void resourceChanged(IResourceChangeEvent event) {
				try {
					event.getDelta().accept(getDeltaVisitor());
				} catch (CoreException e) {
					markInvalid();
				}
			}
		};
		getWorkspace().addResourceChangeListener(listener,
				IResourceChangeEvent.POST_CHANGE);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.AbstractOperation#dispose()
	 */
	public void dispose() {
		if (listener != null) {
			getWorkspace().removeResourceChangeListener(listener);
		}
		super.dispose();
	}
	/**
	 * Mark this operation invalid due to some external change. May be used by
	 * subclasses.
	 *