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: Wed, 08 Jun 2022 13:47:28 +0200
> 
> But if we had this facility (i.e., a way to make Emacs call some
> function after `C-g'-ing a lot during redisplay), then we can start
> experimenting -- and users can, too.  So I think having a
> `break-during-redisplay-function' variable that specifies something to
> be called in these situations would allow some possible progress in this
> area.

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.

The other problem is that I don't know how to do this safely.