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

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

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Open emacs -nw (or on MS-DOS, just emacs.exe); then, type:

 C-h n C-x h

observe that the text representing icons within the left margin is also
highlighted.  Now, move the mouse over a link on a line that contains
such an icon: the mouse face will be displayed one column to the left of
its proper location.

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

[Eli Zaretskii]

> Date: Mon, 07 Aug 2023 16:55:53 +0800
> From:  Po Lu via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Open emacs -nw (or on MS-DOS, just emacs.exe); then, type:
> 
>  C-h n C-x h
> 
> observe that the text representing icons within the left margin is also
> highlighted.

I see this, both on GNU/Linux and on MS-Windows in the -nw session,
but I don't think this is a bug.

> Now, move the mouse over a link on a line that contains such an
> icon: the mouse face will be displayed one column to the left of its
> proper location.

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'?

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.

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

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

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.

> 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.

> 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.

Thanks.

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

[Eli Zaretskii]

> 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?

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

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Eli Zaretskii <eliz@gnu.org> writes:

> 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.

Considering this, and that:

> Could be.  Patches welcome.

I just installed a fix for this, I'm closing this bug.  Thanks for
shedding light on this.