bug#73734: [PATCH] Fix tmm menu layout

[Eli Zaretskii <eliz@gnu.org>]

> From: Manuel Giraud <manuel@ledu-giraud.fr>
> Cc: martin rudalics <rudalics@gmx.at>,  73734@debbugs.gnu.org
> Date: Thu, 10 Oct 2024 20:00:59 +0200
> 
> > What is the "selection character" in this image?
> 
> On the image below, "n" is what I called the selection character for
> "Next Marked" while "* c" is the keybinding for "Change Marks...".  The
> proximity of those two makes this hard to read IMO.

Ah, I see now what you meant.  But if this is the problem, then
changing the column width is not a reliable solution, because you
cannot know in advance what will be the width of the SPC glyph in a
font people use.  I suggest to use 'display' properties instead, for
example '(space . (:width N)), where N is the number of canonical
columns we want the space to take on display.

> >> This patch tries to solves this issue.
> >
> > Can you tell how?  All I see is a different value for colwidth.  I
> > guess I'm missing something.
> 
> Yes but this different colwidth would leave more space between a
> keybinding and the "selection character" of the next column.  But, I
> have to say that it would be hard to prove that it will work for every
> possible settings.

Yes, I think using the 'display' property will be more reliable.

> >> Here, how I justify the modification of `colwidth':
> >> 
> >>       - I don't think we need the "(min 30)" part since, if the frame is
> >>         wide enough, we always get a colwidth of 30.
> >>         
> >>       - I don't think "(window-width)" is what we need since, by
> >>         default, the *Completions* buffer will use the full frame width.
> >
> > Martin, is that guaranteed?
> >
> > And even if it is, what's the harm in keeping window-width?
> 
> I don't think that a full frame width *Completions* buffer is
> guaranteed: it is only what I see with "emacs -Q".
> 
> Keeping window-width in this calculation seems a bit strange because, by
> default, it has nothing to do with the *Completions* buffer window
> width.

Which window's width does this return in this case?