bug#19872: 24.4; UTF8 characters of unusual width (Gnus markers)

[Eli Zaretskii <eliz@gnu.org>]

> From: Sebastien Vauban <sva-news@mygooglest.com>
> Cc: 19872@debbugs.gnu.org
> Date: Mon, 16 Feb 2015 10:45:14 +0100
> 
> >> Is there a solution to that, to guarantee that the alignment can be
> >> correct?
> >
> > Only if Gnus will align text using the :align-to display property,
> > instead of inserting whitespace characters.
> 
> So, I take it for granted that it doesn't use it yet.

I guess, judging by your description.  I don't use Gnus, but you can
easily verify that by looking at each character in the offending line
with "C-x =": if all of the whitespace characters are simple blanks or
TABs, then you know.

> Is this quite new?

You mean, :align-to?  It was new 15 years or so ago.

> >> Worse, it seems that the same UTF8 char can have a "correct" width in
> >> some fonts, and not in others...
> >
> > Of course: it depends on the dimensions of the glyphs in each font.
> 
> Yes, but I was wondering (or hoping) if there was a mechanism in Emacs
> to sort of zoom in/out the characters so that they'd take the same space

No, it doesn't.  (Is that at all possible?  I'm not expert on fonts.)
Emacs simply chooses a font whose size matches the best what it needs.

> regardless of their (buggy?) definition (buggy when in
> a non-proportional font)...

They are not buggy.  The font designer(s) decided which size to use
for each glyph.  It's a profession and a discipline.

> PS- This problem may occur, maybe, because of automatic font replacement
> for characters not found in my default font (Consolas)?

Yes, and I'm guessing this is what happened in your case.  You can see
which font each character came from by using "C-u C-x =".