bug#59947: closed (30.0.50; Underline of tab-bar face does not respect x-underline-at-descent-line)

[GNU bug Tracking System]

Your message dated Sat, 10 Dec 2022 21:44:24 +0200
with message-id <83359nvyav.fsf@gnu.org>
and subject line Re: bug#59947: 30.0.50; Underline of tab-bar face does not 
respect x-underline-at-descent-line
has caused the debbugs.gnu.org bug report #59947,
regarding 30.0.50; Underline of tab-bar face does not respect 
x-underline-at-descent-line
to be marked as done.

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59947: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=59947
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--- Begin Message --- Subject: 30.0.50; Underline of tab-bar face does not respect x-underline-at-descent-line Date: Sat, 10 Dec 2022 15:22:20 -0300

Description:

Apparently, the underline property of tab-bar (and tab-bar-*) face does
not respect the option x-underline-at-descent-line.  When
x-underline-at-descent-line is set to t, the underline is displayed at
descent level (below of bottom box), but in tab-bar face it's displayed
at the baseline (above of bottom box).  See steps below and attached
images for more information.

Steps:

1) emacs -q (master "fbbf3610fd5b27873e13cfd7702d5b0bbb15c2f8")

2) Enable tab-bar and tab-line:

(progn
  (tab-bar-mode 1)
  (global-tab-line-mode 1))

3) Set box, overline and underline of tab-tab face:

(set-face-attribute 'tab-bar
                    nil
                    :box '(:style flat-button
                           :line-width 12
                           :color "green")
                    :overline "red"
                    :underline "red")

Result: a green box is displayed in tab-bar, a red overline is displayed
above of top box and a red underline is displayed above of bottom box.

4) Set box, overline and underline of tab-line face:

(set-face-attribute 'tab-line
                    nil
                    :box '(:style flat-button
                           :line-width 12
                           :color "yellow")
                    :overline "blue"
                    :underline "blue")

Result: a yellow box is displayed in tab-line, a blue overline is
displayed above of top box and a blue underline is displayed above of
bottom box.

See image step-4.png

Note: I am not sure why the underline and overline of tab-bar face are
not extended as in tab-line.  I tried many approaches (e.g. using
:extend t, using other tab-bar-* faces, tweaking tab-line-format etc)
but nothing worked for me.  Perhaps it's something related to the bug
reported here.

5) Set x-underline-at-descent-line:

(setopt x-underline-at-descent-line t)

Result: The tab-line underline is now displayed below the bottom box,
but the tab-bar underline is not affected.  I tried many approaches
(e.g.: tweaking the variables x-underline-at-descent-line,
x-use-underline-position-properties and underline-minimum-offset, using
other tab-bar-* faces etc) to make it work, but nothing worked for me.

See image step5.png

step-4.png
Description: PNG image

step-5.png
Description: PNG image

---
Gabriel

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#59947: 30.0.50; Underline of tab-bar face does not respect x-underline-at-descent-line
>
>
>
>
> Date: 
>
> Sat, 10 Dec 2022 21:44:24 +0200
>
>
>
>
> > From: Gabriel <gabriel376@hotmail.com>
> > Date: Sat, 10 Dec 2022 16:28:52 -0300
> > 
> > Eli Zaretskii <eliz@gnu.org> writes:
> > >
> > > The x-underline-at-descent-line option is only supported for windows
> > > that display buffers.  And the tab bar uses a pseudo-window that has
> > > no buffer (like the tool bar in builds that don't have a
> > > toolkit-provided tool bar).
> > 
> > Thanks for the explanation, Eli.  In this case, feel free to close this
> > bug report.
> > 
> > So it works for tab-line because it is displayed in a "real" window,
> > right?
>
> Yes.  A tab-line is similar to the mode-line and a header-line, and
> uses the same display routines.
>
>
> --- End Message ---