bug#59719: 29.0.60; emacs-news-mode does not adjust the width of the fringe to accommodate the outline icons

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: justksqsf@gmail.com,  59719@debbugs.gnu.org
> Date: Wed, 30 Nov 2022 20:30:16 +0200
> 
> > Why not use string-pixel-width, and divide by what default-font-width
> > returns?
> 
> This means to iterate over all icons and get their maximal width.

Are they so different in their dimensions?  And how many icons do we have in
this case?

> There is one thing that I don't understand about margins: could you clarify
> how the default width of a character cell is calculated?  Is it based
> on the default font size?

Yes, based on the default face's font.  Exactly like the dimensions of the
text-area of the window are calculated.