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

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Sat, 13 Mar 2021 01:47:25 -0600
> Cc: alan@idiocy.org, 47074@debbugs.gnu.org
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> @@ -2385,9 +2385,9 @@ 'checkbox
> >>    ;; We could probably do the same job as the images using single
> >>    ;; space characters in a boxed face with a stretch specification to
> >>    ;; make them square.
> >> -  :on-glyph "checked"
> >> +  :on-glyph "ui/checkbox-checked"
> >>    :off "[ ]"
> >> -  :off-glyph "unchecked"
> >> +  :off-glyph "ui/checkbox"
> >>    :help-echo "Toggle this item."
> >>    :action 'widget-checkbox-action)
> >
> > How will this work in an Emacs session that doesn't support SVG?  The
> > images/ui/ directory has only SVG images.  Am I missing something?
> 
> There are only SVG images in that directory, yes.
> 
> IIUC, it would show the :on and :off text on such configurations,
> i.e. "[X]" and "[ ]".

That'd be a regression, no?  Can we arrange for the old XPM files to
be used if SVG is not available?