bug#17678: 24.4.50; Feature Request -- calculate new `window-start` & `window-end` before visual redisplay

[Eli Zaretskii]

> From: Keith David Bershatsky <esq@lawlist.com>
> Date: Fri, 13 Jun 2014 11:24:01 -0700
> Cc: 17678@debbugs.gnu.org
> 
> I believe splitting up the work between the two hooks may be possible -- I 
> will need to revise the conditions once I identify additional situations.  As 
> far as I can tell, the `window-scroll-functions` hook is NOT triggered when 
> `point` STAYS between *old* `window-start` and *old* `window-end`.  So when 
> `point` STAYS between *old* `window-start` and *old* `window-end`, I will 
> need to use the `post-command-hook`.  When point moves BEYOND *old* 
> `window-start` or `*old* `window-end`, then the `window-scroll-functions` 
> hook can take over -- with a forced new `(window-end nil t)`.

Why do you care about the situation where point stays inside the same
window limits?