Segmentation fault when gtk_main_quit

[Ingvar Tjostheim <ingvar isafold com>]

I have a OpenGL program that uses GNOME for GUI before the GL part starts.
So that when user has given some input I'd like the GNOME part of the program to finish.

There's a button int the GNOME "window" that closes it and starts GL with parameters.
If I use this code the window hides perfectly:
  gtk_widget_destroy(window);
  while (g_main_iteration(FALSE)) 
    gtk_main_quit();
but when the user exits the GL part I get an segmentation fault

If I use this code:
  gtk_widget_destroy(window);
or this:
  gtk_widget_hide(window);
the window doesn't even close.

What causes the segmentation fault, and how can I both hide the window and avoid the segmentation fault?