Why do I get this error message?

[Al Amaral <ama jabba East Sun COM>]

In the app that I'm working on the top level widget is a GnomeApp.
If I hit the close window button on the window manager menu everything
works fine, i.e. my code intercepts the event and pops up a dialog asking
if I want to quit.  However, if I hit the close window button (X) I get
the dialog, along with another error dialog which says:

"The window "foo" is not responding.
 Force this application to exit?
 (Any open documents will be lost.)"

with buttons for cancel and kill application...  Does anyone know
where this dialog comes from, and how I get rid of it?

--Al--