bug#28844: 26.0.90; display-line-numbers-mode should call window-configuration-change-hook

[Eli Zaretskii <eliz@gnu.org>]

> From: Noam Postavsky <npostavs@users.sourceforge.net>
> Cc: Eli Zaretskii <eliz@gnu.org>,  28844@debbugs.gnu.org,  agrambot@gmail.com
> Date: Thu, 07 Dec 2017 21:43:29 -0500
> 
> Paul Rankin <hello@paulwrankin.com> writes:
> 
> Whereas my understanding of #20 is that Eli thinks adding a dedicated
> hook would be less efficient than using post-command-hook.
> 
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=28844#20

Not just less efficient, but also much more problematic for the
display code as a whole from the implementation POV.

> PS You seem awful quick to jump to Ad Hominem, it makes resolving bug
> reports needlessly unpleasant.

Well put, thanks.  "Unpleasant" indeed.  (I might have used stronger
words here, but then I'm the one who is being attacked, so I'm
probably -- what was that word? ah, yes: "biased".)

More to the point, I've offered help, based on my experience in
adapting other packages to this new feature.  See

  https://debbugs.gnu.org/cgi/bugreport.cgi?bug=28844#53

I'm willing to do more, and propose working code, but being unfamiliar
with your package, I need some help understanding what is the expected
behavior when certain display-related attributes change.  For example,
what should happen if the user enlarges or makes smaller the default
face's font with the likes of "C-x +"?  I'm asking this because the
effect on the display margins is similar, so I wanted to look what the
package does in that case, but it seems to do nothing: the margin
dimensions are not changed as I'd expect them to.  So I couldn't do
more than just suggest a way to solve this.  Maybe I missed some
setting or knob.

I actually think the problem is not so hard and could be solved quite
easily, but your help, Paul, is needed to make this happen.