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

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Thu, 11 Mar 2021 10:51:19 -0600
> 
> Obviously how these look depends on the fonts you have installed.  On my
> machine, the "Fira Code" font is used, which makes them look very good.

Exactly, so depending on a font to produce good results is not
necessarily a good idea.

> Perhaps we could prefer Unicode icons if they are available, and fall
> back on icons if not.  It seems like we can use `char-displayable-p' to
> see if there is any font that can display that codepoint.

char-displayable-p is expensive, though.  And it does nothing against
the not-so-pretty fonts, of course

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?