Actually, you CAN capture ActivateWindow, DeactivateWindow, ShowWindow, and HideWindow events. But they're only exposed through the Visual FoxPro API, which means writing C code, and a significant learning curve.

If you're curious, check the help file under:
Reference -> Language Reference -> API Library Construction

For the events you can trap, look at
MODI COMM HOME() + "Samples\api\pro_ext.h"
and search for EventRec.what