bug#57962: 29.0.50; Odd font choices

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: luangruo@yahoo.com,  57962@debbugs.gnu.org, Stefan Kangas
>  <stefankangas@gmail.com>
> Date: Mon, 17 Oct 2022 11:57:12 +0200
> 
> So there is no way to say "I have font X, give me font Y of the same
> size".

Maybe with "fixed-*" fonts this is so.  But isn't True Type fonts
scalable, so that we can request any size and get what we request?

> So I think we just have to mitigate this on a practical level, and the
> practical problem we have is that we expect a (fixed pitch) `default' font
> to have the same size as the `help-key-binding' font, since we mix these
> faces so much in our displays, and we want them to line up in tabular
> outputs.
> 
> This means that we can either remove ":inherit fixed-pitch" from the
> latter face -- and that would fix the problem in 99.7% of the cases.
> But ideally, we'd like to have that face be fixed-pitch even if
> `default' uses a proportional font (which is possibly, but very very
> unusual).  To achieve that we'd have to implement something like
> 
>   :inherit (if (monospacep 'default) 'default 'fixed-pitch)
> 
> or something?

Is that because ":spacing 'm" doesn't work (it seems to work for me)?
If so, I think we should try fixing that instead of introducing new
wizardry.