bug#56682: locked narrowing

[Eli Zaretskii]

> Date: Fri, 02 Dec 2022 09:16:08 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: monnier@iro.umontreal.ca, 56682@debbugs.gnu.org, dgutov@yandex.ru
> 
> In which case we are back to the alternative solution, which is to trigger 
> rescanning on each redisplay cycle.  Which might, after all, be the 
> simplest and safest solution.

If the region we scan is limited by some reasonably large size, that could
indeed be the best solution.