This example updates an Undo and Redo menu handler's status.

Visual Basic

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Private Sub AnnAutomation_UndoRedoChanged(ByVal manager As AnnAutomationManager)    ' subscribe to the UndoRedoChanged event of all automations    For Each automation As AnnAutomation In manager.Automations       AddHandler automation.UndoRedoChanged, AddressOf automation_UndoRedoChanged    Next automation End Sub Private Sub automation_UndoRedoChanged(ByVal sender As Object, ByVal e As EventArgs)    Dim automation As AnnAutomation = CType(IIf(TypeOf sender Is AnnAutomation, sender, Nothing), AnnAutomation)    ' assume _menuItemUndo is the Undo menu, and _menuItemRedo is the Redo menu    _menuItemUndo.IsEnabled = automation.CanUndo    _menuItemRedo.IsEnabled = automation.CanRedo End Sub

C#

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private void AnnAutomation_UndoRedoChanged(AnnAutomationManager manager)  {     // subscribe to the UndoRedoChanged event of all automations     foreach(AnnAutomation automation in manager.Automations)        automation.UndoRedoChanged += new EventHandler(automation_UndoRedoChanged);  }  private void automation_UndoRedoChanged(object sender, EventArgs e)  {     AnnAutomation automation = sender as AnnAutomation;       // assume _menuItemUndo is the Undo menu, and _menuItemRedo is the Redo menu     _menuItemUndo.IsEnabled = automation.CanUndo;     _menuItemRedo.IsEnabled = automation.CanRedo;  }

This event will be fired when the undo/redo buffer changes. This gives the application a chance to update the user interface if needed.

The undo/redo buffer changes whenever an object inside the Container changes either by user interaction through the user interface or by code.

You can use the CanUndo and CanRedo property to determine whether this AnnAutomation can undo or redo an operation.

For more information, refer to Undoing WPF Automation Operations.

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Vista, and Windows Server 2003 family

Reference