bug#67794: 30.0.50; mouse-face is not respected on SVG images

[Eli Zaretskii <eliz@gnu.org>]

> From: Manuel Giraud <manuel@ledu-giraud.fr>
> Cc: alan@idiocy.org,  gerd.moellmann@gmail.com,  67794@debbugs.gnu.org
> Date: Tue, 19 Dec 2023 15:39:28 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> > Before we install this, we had better be sure we understand the
> >> > consequences, since we have never before done anything like that in
> >> > mouse-highlight implementation.
> >> >
> >> > OK?
> >> 
> >> Ok.  Maybe I could look at the evolution of the memory footprint.  How
> >> do you think I could do this?
> >
> > Depending on your system, there surely is some tools which show the
> > memory map of a given process in some graphical manner.
> >
> > If worse comes to worst, you could use 'top' of "M-x proced" in
> > another Emacs, although that will only show a single figure or two.
> 
> Ok, I thought you were thinking of something into Emacs.  I'll try to do
> something like this.

Thanks.

Btw, does this only work for SVG, and if librsvg is later than some
recent version?  Or does this work with any image?  If the former,
this code should be executed only conditionally, under those
conditions under which it really changes the background color of an
image.