bug#65121: 30.0.50; Text ``icons'' in margins receive region face

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: 65121@debbugs.gnu.org
> Date: Mon, 07 Aug 2023 21:04:09 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I see this, both on GNU/Linux and on MS-Windows in the -nw session,
> > but I don't think this is a bug.
> 
> This doesn't happen on X frames.

It does if you customize icon-preferences to use only 'text'.  The
default icon on GUI frames is an SVG image, which defines its own
background color, so the region-face background doesn't show.

> > This I cannot reproduce on MS-Windows.  (I don't have a GNU/Linux
> > system with a mouse-capable TTY, so I cannot try there.)  Or maybe I
> > don't understand what you mean by "link on a line that contains such
> > an icon"?  By "links" do you mean symbols quoted 'like this'?
> 
> Yes.  Perhaps this bug is specific to the MS-DOS build; msdos.c's
> variant of tty_draw_row_with_mouse_face seems to lack special treatment
> for the margin area that is present in term.c.

Could be.  Patches welcome.

> > Strangely, not all of the links are highlighted with mouse-face, only
> > some.  And I cannot understand what makes different instances of a
> > link behave differently.
> 
> Or maybe we are witnessing different manifestations of the same bug.

You mean, you see all of 'quoted' symbols show as links on GUI frames?