Bug 164375 [Undo] - WorkspaceUndoUtil shouldn't reset change count for any context
N20061112-0010, WinXP I noticed with the WorkspaceUndoMonitor tracing on that the workspace change count was being reset when undoing and redoing text changes from an editor. This should not be the case. The workspace undo monitor listener should only be responding to undo/redo operations that have the workbench/workspace context.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/undo/WorkspaceUndoMonitor.java
* Prefix to use on debug info
	 */
	private static String DEBUG_PREFIX = "Workspace Undo Monitor:  "; 
	/**
	 * Get the singleton instance of this class.
	 * 
	 * @return the singleton instance of this class.
	 */
	public static WorkspaceUndoMonitor getInstance() {
		if (instance == null) {
			instance = new WorkspaceUndoMonitor();
		}
		return instance;
	}
	/**
	 * Number of workspace changes that have occurred since the last undoable
	 * operation was executed, undone, or redone.
	 */
	private int numChanges = 0;
	/**
	 * The IUndoableOperation in progress, or <code>null</code> if there is
	 * none in progress.
	 */
	private IUndoableOperation operationInProgress = null;
	/**
	 * Resource listener used to determine how often to validate the workspace
	 * undo history.
	 */
	private IResourceChangeListener resourceListener;
	/**