bug#47074: Replace XPM icons with Unicode codepoints in customize/widgets

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Thu, 11 Mar 2021 11:51:45 -0600
> Cc: 47074@debbugs.gnu.org
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > char-displayable-p is expensive, though.
> 
> Could we perhaps cache the results if it is prohibitively slow?

It isn't prohibitively slow, just slow.

> > So I generally find the idea of using characters for this purpose
> > problematic; we've seen these problems in other places in Emacs.  Why
> > not use SVG images instead?
> 
> I think SVG is obviously much preferable to XPM, but there is still the
> problem that the images don't scale with the text.  Do we have a general
> solution to that?  If not, should we have one?

With SVG, I believe we could.  (We can scale other kinds of images as
well, but they don't look well when enlarged, AFAIK.)