Document.UndoEnabled Property (Visio)
Determines whether undo information is maintained in memory. Read/write.
When Microsoft Visio starts, the value of the UndoEnabled property is True. Setting the value of the UndoEnabled property to False discontinues the collection of undo information in memory and clears the existing undo information.
You should attempt to maintain the property at its current value across the complete operation that you perform. In other words, use code structured like this:
The following Microsoft Visual Basic for Applications (VBA) macro shows how to use the UndoEnabled method to disable and then re-enable undo behavior in Visio.