In a custom editor, I have several serialized properties. As expect when I change any of them, GUI.Changed is set to true. However, if I undo a change, the value(s) for whatever serialized property was changed is reflected in the custom editor but as this value is changed, the GUI.Changed is never set. How do I detect when a value in a serialized property has been changed as a result of an undo operation? I thought serialized properties handled that automatically... what am i missing here?