marc@ubuntu:~$ XLIB_SKIP_ARGB_VISUALS=1 firefox
NP_Initialize
New
SetWindow
SetWindow
SetWindow
New
SetWindow
SetWindow
NewStream
WriteReady
Write
The program 'Gecko' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadImplementation (server does not implement operation)'.
  (Details: serial 48 error_code 17 request_code 129 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.)
marc@ubuntu:~$