Problem running GTK2 apps

[ml <ml knorke in-berlin de>]

Hi,

I have a general problem with running GTK2 things.  I'm
running Debian unstable, i.e. libgtk2.0 version 2.0.2(-5)
and gtk2.0-example 2.0.2(-5).  Unfortunately, I get the
following message:

$ gtk-demo 
The program 'gtk-demo' received an X Window System error.
This probably reflects a bug in the program.
The error was '202'.
  (Details: serial 428 error_code 202 request_code 155 minor_code 8)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

or:

$ gtk-demo --sync
The program 'gtk-demo' received an X Window System error.
This probably reflects a bug in the program.
The error was '202'.
  (Details: serial 709 error_code 202 request_code 155 minor_code 5)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Same with metacity:

$ metacity
Bug in window manager: Unexpected X error: 202 serial 1578 error_code 202 request_code 155 minor_code 8)
Aborted

What's wrong here? Note, that GNOME 1.4 runs fine.
Thanks in advance for any useful hint.

Cheers!