Bug 105697 [Undo] - OperationHistoryEvent - cannot distinguish between canceled event or failed event
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/DefaultOperationHistory.java
OperationHistoryEvent event) {
		if (operation instanceof IAdvancedUndoableOperation) {
			try {
				((IAdvancedUndoableOperation) operation).aboutToNotify(event);
			} catch (Exception e) {
				handleNotificationException(e);
			}
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.IOperationHistory#redo(org.eclipse.core.commands.operations.IUndoContext,
	 *      org.eclipse.core.runtime.IProgressMonitor,
	 *      org.eclipse.core.runtime.IAdaptable)
	 */
	public IStatus redo(IUndoContext context, IProgressMonitor monitor,
			IAdaptable info) throws ExecutionException {
		Assert.isNotNull(context);
		IUndoableOperation operation = getRedoOperation(context);
		
		if (operation == null)
			return IOperationHistory.NOTHING_TO_REDO_STATUS;
		
		if (!operation.canRedo()) {
			if (DEBUG_OPERATION_HISTORY_UNEXPECTED) {
				System.out
						.print("OPERATIONHISTORY >>> Redo operation not valid - ");  
				System.out.print(operation);
				System.out.println();