While using Gnus, the display of one particular summary buffer is
causing all of the frames on this (remote X11) terminal to close.  It
does not, however, crash emacs.  The message in my *Messages* buffer is:

X protocol error: BadFont (invalid Font parameter) on protocol request 56
Serial no: 20736
Failing resource ID (if any): 0x0
Minor code: 0
This is a bug!  Please report this to bug-gnu-emacs@gnu.org!

With some difficulty (attempting to save the buffer also causes the
problem) I was able to extract the buffer as a text file.  Viewing that
file in this remote emacs also triggers the problem, so I will likely be
able to recreate this problem on my end.  I am attaching the gzipped
contents of the file in question to this message.

I do not yet know if this problem will happen if I am not in a remote
frame.  Determining that will have to wait until I return home from
work later today.

This emacs is compiled unoptimized with debugging enabled.  I would be
very interested in figuring out where I could add a breakpoint to try to
figure out what is causing this problem.