I just found a way to repeat a BadWindow error in xemacs 21.1.
When I played with the beta a few months ago it occasionally showed
the same behaviour, but I could not figure out how to repeat it at
the time.
Procedure:
1. Help-bubbles enabled (those small, yellow boxes).
2. Place the mouse cursor close to the lower edge of a toolbar
button.
3. Wait for the help-bubble to appear, it must overlap with the
frame below.
4. Now move the mouse cursor to the right and into the help-bubble.
You immediately get one X error message on your xterm:
xemacs: X Error of failed request: BadWindow (invalid Window parameter)
Major opcode of failed request: 40 (X_TranslateCoords)
Resource id in failed request: 0x800a7e
Serial number of failed request: 2908929
Current serial number in output stream: 2908929
xemacs: X Error of failed request: BadWindow (invalid Window parameter)
etc...
xemacs: X Error of failed request: BadWindow (invalid Window parameter)
etc...
Enclosed gif with hand drawn mouse cursor illustrates above.
Apologies if this is old news and has already been fixed.
--
Manfred