bug#45898: 27.1; wedged in redisplay again

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Fri, 10 Jun 2022 11:02:06 +0200
> Cc: Emacs-hacker2018@jovi.net, 45898@debbugs.gnu.org
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I don't think it's a very good idea to switch buffers behind user's
> > back.  It is better to tell the user there's a problem and let them do
> > whatever is right for them.
> >
> > But yes, we could also consider something like that -- if we find a
> > safe way of doing it.
> 
> The scenario here is that the user is hitting `C-g' repeatedly while in
> redisplay, so it's not exactly behind the user's back...

I prefer a solution whereby Emacs discovers the problem automatically,
leaving C-g for "other circumstances".  After all, how hard can it be
to figure out that some buffer or window takes too long to redisplay?

> Finding a safe way to interrupt redisplay is the problem, though.

I have an idea and will work on it soon.