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
for (int i = 0; i < listenerArray.length; i++)
			try {
				listenerArray[i].historyNotification(event);
			} catch (Exception e) {
				handleNotificationException(e);
			}
	}
	private void notifyAboutToExecute(IUndoableOperation operation) {
		if (DEBUG_OPERATION_HISTORY_NOTIFICATION) {
			System.out.print("OPERATIONHISTORY >>> ABOUT_TO_EXECUTE ");  
			System.out.print(operation);
			System.out.println();
		}
		notifyListeners(new OperationHistoryEvent(
				OperationHistoryEvent.ABOUT_TO_EXECUTE, this, operation));
	}
	/*
	 * Notify listeners that an operation is about to redo.
	 */
	private void notifyAboutToRedo(IUndoableOperation operation) {
		if (DEBUG_OPERATION_HISTORY_NOTIFICATION) {
			System.out.print("OPERATIONHISTORY >>> ABOUT_TO_REDO ");  
			System.out.print(operation);
			System.out.println();
		}
		notifyListeners(new OperationHistoryEvent(
				OperationHistoryEvent.ABOUT_TO_REDO, this, operation));
	}
	/*
	 * Notify listeners that an operation is about to undo.