'Usage
Dim instance As UndoManager
instance.CancelAction()
public void CancelAction()
Remarks
This method is intended to be used in event handlers when an UndoAction
raises an event that permits cancelling of the action. You can call this method
and then use PerformUndoAction to do another UndoAction instead, but you must be
sure to cancel the default processing in the event handler to prevent the original
UndoAction that raised the event from doing its processing too.