To select an annotation through code, set the annotation's Selected property to true.
If you add an event handler for the UndoManager.UndoRequest event it will be raised when Undo is called. The event args provides an AnnotationUndo class that tells you which object, usually an annotation, is affected in the Item property. It's possible that property will not be an annotation, so be sure to verify the object type.
Glenn Chittenden Jr.
Atalasoft Development Team