The restest.c test program that was incorporated into
our X packages does printf()'s inside XGrabServer().

This is real bad, because printf() can block on the
terminal emulator, which is blocking on the server,
so the X session hangs with a server grab.
 
The program needs to retrieve everything, store it,
ungrab the server, XFlush(TheDisplay), then print
stuff out.

(If you don't XFlush(), then the server probably won't
get the ungrab.)