Getting X error while runing GTK+ application

Question

I have written a GTK+ application but I am getting the following X Window error while running it:

    The program 'TestApp' received an X Window System error.
    This probably reflects a bug in the program.
    The error was 'BadMatch (invalid parameter attributes)'.
      (Details: serial 222 error_code 8 request_code 2 minor_code 0)
      (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.)

What might be the cause of this error? I have written this app in in C.

Answer 1

I would try doing as it suggests: run the application with the --sync cmd option and start it in a debugger, so you can see which line causes the error.