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

[Manuel Giraud]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Manuel Giraud <manuel@ledu-giraud.fr>
>> Cc: alan@idiocy.org,  67794@debbugs.gnu.org
>> Date: Wed, 13 Dec 2023 17:50:08 +0100
>> 
>> BTW, do you know why mouse-highlight is this way?  Is it because it
>> was an afterthought of the display engine or is it because of
>> performance issues or…?
>
> How would you design it instead?
>
> I'm not saying that what we have is the only possible design, but I'm
> curious what alternative design ideas could be used.

Sorry I do not have an alternative design idea 😅.  It's just that from
my, obviously limited, point of view the Emacs display engine is a work
horse that could handled many cases regarding how to display glyphs and
I was wondering why it was not used for mouse highlight also.

> Btw, AFAIU the person who at the time decided how this will work is
> here: it's Gerd (CC'ed).  Maybe he can share his memories about why he
> ended up with this design.

Thanks for summoning Gerd.  I have an answer now even though I do not
have the knowledge to understand it fully.
-- 
Manuel Giraud