bug#45898: 27.1; wedged in redisplay again

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Emacs-hacker2018@jovi.net,  45898@debbugs.gnu.org
> Date: Thu, 09 Jun 2022 12:25:19 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > One problem with this is that we already have the "emergency exit"
> > feature, which is triggered by 2 or more C-g's.  This only works
> > reliably on TTY frames, but it's still a feature we don't want to
> > lose.
> 
> I think that could be made to fit into the general feature, really.  The
> "emergency exit" feature currently queries "Abort (and dump core)?" if I
> remember correctly?  We could extend that to "Abort, enter
> so-long-mode (or whatever)...?" etc.

That's called from a signal handler, where we cannot do anything
non-trivial, definitely not call Lisp.  We need some machinery that is
currently missing.

I also think that activating a mode is not TRT in these cases.  I'm
trying to think about something better, like mark the offending window
as "not for display" or somesuch.