Bug 94400 [Undo] - After successful undo, should operation be disposed by framework if it cannot be redone?
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/DefaultOperationHistory.java
*/
	private void notifyAboutToUndo(IUndoableOperation operation) {
		if (DEBUG_OPERATION_HISTORY_NOTIFICATION) {
			System.out.print("OPERATIONHISTORY >>> ABOUT_TO_UNDO ");  
			System.out.print(operation);
			System.out.println();
		}
		notifyListeners(new OperationHistoryEvent(
				OperationHistoryEvent.ABOUT_TO_UNDO, this, operation));
	}
	/*
	 * Notify listeners that an operation has been added.
	 */
	private void notifyAdd(IUndoableOperation operation) {
		if (DEBUG_OPERATION_HISTORY_NOTIFICATION) {
			System.out.print("OPERATIONHISTORY >>> OPERATION_ADDED ");  
			System.out.print(operation);
			System.out.println();
		}
		notifyListeners(new OperationHistoryEvent(
				OperationHistoryEvent.OPERATION_ADDED, this, operation));
	}
	/*
	 * Notify listeners that an operation is done executing.
	 */
	private void notifyDone(IUndoableOperation operation) {
		if (DEBUG_OPERATION_HISTORY_NOTIFICATION) {
			System.out.print("OPERATIONHISTORY >>> DONE ");  
			System.out.print(operation);
			System.out.println();