On debugging window system locking problems

[Moon@STONY-BROOK.SCRC.Symbolics.COM (David A. Moon)]

    Date: Wed, 12 Sep 90 16:41:38 EDT
    From: kristina@cmi.com (Kristina Fayyad)

    Is there an elegant way to get out of the Screen Controller
    Lock error?

To find out why the lock is locked, press Function Suspend to get into
the cold-load stream (since you can't use the regular window system)
then use the Debug Process command to debug the process that is waiting
(presumably Dynamic Lisp Listener 1).  That should tell you who is holding
the screen controller lock.  Use the Debug Process command again to
debug that process and get a backtrace of what's going on with it (normally
things that hold the Screen Controller Lock don't run for very long, just
long enough to generate some output).  If the problem is in your code or
your user's init file, fix it; if it's in Symbolics code, report it to
software support.

Function Control-Clear Input is the documented way to unlock all window
system locks.  This is a big hammer, but not nearly as big a hammer as
warm booting.  After you press Resume enough times to get out of those
Debug Process commands and out of the cold load stream, you can use 
Function Control-Clear Input to get the window system going again so you
can send your bug report.