bug#19395: 25.0.50; Setting left fringe to 0 messes up window-width

[Eli Zaretskii]

> From: Titus von der Malsburg <malsburg@posteo.de>
> Cc: 19395@debbugs.gnu.org
> Date: Tue, 16 Dec 2014 19:28:45 -0800
> 
> I see, thanks for explaining.  Perhaps it would make sense to amend the
> documentation of `window-width' because this is easy to misunderstand
> and I suspect that I'm not the only one who consults window-width in
> order to determine how much columns are available for text display.

Done.