gtk-rao-990117-0.patch allows a MT program to call exit() without the
possibility of receiving an unexpected Xlib async reply or X IO error.
All gtk atexit functions have been wrapped in
GDK_THREADS_[ENTER/LEAVE].  gdk_exit_func grabs the gdk lock and never
releases it -- this insures that upon closing the X server connection
and before the program terminates, any gdk calls on other threads will
not be handled.

The patch was made against the CVS tree on 1998-01-17.