This example selects the first annotation object in the automation container, deletes it, performs an undo, and then redos the operation.

Visual Basic

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Private Sub AnnAutomation_Undo(ByVal automation As AnnAutomation)    If automation.Container.Children.Count > 0 Then       ' select the first object in the automation       automation.StartEditing(CType(IIf(TypeOf automation.Container.Children(0) Is AnnObjectBase, automation.Container.Children(0), Nothing), AnnObjectBase), False)       MessageBox.Show("Object has been selected. Next delete it")       ' delete this object       automation.Delete()       MessageBox.Show("Object has been deleted. Next undo the operation to bring the object back")       ' undo the delete operation       automation.Undo()       MessageBox.Show("Operation has been undone and the object is back. Next redo the operation to delete the object again")       ' redo the delete operation       automation.Redo()       MessageBox.Show("Operation has been redone and the object is deleted again.")    Else       MessageBox.Show("No objects in the container!")    End If End Sub

C#

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private void AnnAutomation_Undo(AnnAutomation automation)  {     if(automation.Container.Children.Count > 0)     {        // select the first object in the automation        automation.StartEditing(automation.Container.Children[0] as AnnObjectBase, false);        MessageBox.Show("Object has been selected.  Next delete it");        // delete this object        automation.Delete();        MessageBox.Show("Object has been deleted.  Next undo the operation to bring the object back");          // undo the delete operation        automation.Undo();        MessageBox.Show("Operation has been undone and the object is back.  Next redo the operation to delete the object again");          // redo the delete operation        automation.Redo();        MessageBox.Show("Operation has been redone and the object is deleted again.");     }     else        MessageBox.Show("No objects in the container!");  }

Use the UndoCapacity property to get or set the number of user actions that can be reversed using the Undo method, or re-applied using the Redo method. The default for the UndoCapacity property is 10 actions.

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