GNU bug report logs - #59620
29.0.50; Wrong global-mode-string position in tab-bar + emacs -nw

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Gabriel <gabriel376 <at> hotmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 29.0.50; Wrong global-mode-string position in tab-bar + emacs -nw
Date: Sat, 26 Nov 2022 18:46:08 -0300

[Message part 1 (text/plain, inline)]

Severity: bug

Description:

The global-mode-string is wrongly positioned in tab-bar when using
"emacs -nw" and multiple windows.  The bug only happens with emacs -nw.

Steps:

1) emacs -Q -nw (master "af545234314601ba3dcd8bf32e0d9b46e1917f79")

2) Eval the following to add display-time-mode right-aligned to tab-bar:

(progn
  (display-time-mode 1)
  (setopt tab-bar-format '(tab-bar-format-tabs-groups
                           tab-bar-separator
                           tab-bar-format-align-right
                           tab-bar-format-global))
  (tab-bar-mode 1))

3) Split window right: C-x 3

Result: the global-mode-string will be wrongly positioned.  It expected
to be right-aligned to the current frame, but it's right-aligned to the
left window.  The position is correct while minibuffer has focus.  See
attached images.

[one-window.png (image/png, attachment)]

[bug.png (image/png, attachment)]

[minibuffer-focus.png (image/png, attachment)]

[Message part 5 (text/plain, inline)]

---
Gabriel

Message #8 received at 59620 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Gabriel <gabriel376 <at> hotmail.com>
Cc: 59620 <at> debbugs.gnu.org
Subject: Re: bug#59620: 29.0.50;
 Wrong global-mode-string position in tab-bar + emacs -nw
Date: Sun, 27 Nov 2022 08:19:57 +0200

> From: Gabriel <gabriel376 <at> hotmail.com>
> Date: Sat, 26 Nov 2022 18:46:08 -0300
> 
> 1) emacs -Q -nw (master "af545234314601ba3dcd8bf32e0d9b46e1917f79")
> 
> 2) Eval the following to add display-time-mode right-aligned to tab-bar:
> 
> (progn
>   (display-time-mode 1)
>   (setopt tab-bar-format '(tab-bar-format-tabs-groups
>                            tab-bar-separator
>                            tab-bar-format-align-right
>                            tab-bar-format-global))
>   (tab-bar-mode 1))
> 
> 3) Split window right: C-x 3
> 
> Result: the global-mode-string will be wrongly positioned.  It expected
> to be right-aligned to the current frame, but it's right-aligned to the
> left window.  The position is correct while minibuffer has focus.  See
> attached images.

Looks like tab-bar-format-align-right is evaluated with the wrong window
being the selected one: it should use the tab-bar pseudo-window to do what
you expect.

Message #11 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Gabriel <gabriel376 <at> hotmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#59620: 29.0.50; Wrong global-mode-string position in
 tab-bar + emacs -nw
Date: Sun, 27 Nov 2022 05:05:58 -0300

Eli Zaretskii <eliz <at> gnu.org> writes:

>
> Looks like tab-bar-format-align-right is evaluated with the wrong window
> being the selected one: it should use the tab-bar pseudo-window to do what
> you expect.

I don't know what is the root cause, but it's a reasonable hypothesis.
Not sure why it only affects "emacs -nw", though.

Do you know how to get the tab-bar pseudo-window?  It seems that
"f->tab_bar_window" it's not exposed from C to elisp.

Anyway, I think it's a bug.  Maybe Juri can help on this.  I will try to
find a fix, but I can't promise.

---
Gabriel

Message #14 received at 59620 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: Gabriel <gabriel376 <at> hotmail.com>
Cc: 59620 <at> debbugs.gnu.org
Subject: Re: bug#59620: 29.0.50; Wrong global-mode-string position in
 tab-bar + emacs -nw
Date: Mon, 28 Nov 2022 09:54:17 +0200

>> Looks like tab-bar-format-align-right is evaluated with the wrong window
>> being the selected one: it should use the tab-bar pseudo-window to do what
>> you expect.
>
> I don't know what is the root cause, but it's a reasonable hypothesis.
> Not sure why it only affects "emacs -nw", though.
>
> Do you know how to get the tab-bar pseudo-window?  It seems that
> "f->tab_bar_window" it's not exposed from C to elisp.

Unless Eli can suggest how to fix `(space :align-to (- right (,hpos)))
to work on TTY frames the same way as it works on GUI frames,
I could try to rewrite it to avoid the keyword `right', i.e. to use
`(space :align-to (,hpos-from-left)) where hpos-from-left could be
calculated by using string-pixel-width on the text from the left side.

Message #17 received at 59620 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Juri Linkov <juri <at> linkov.net>
Cc: gabriel376 <at> hotmail.com, 59620 <at> debbugs.gnu.org
Subject: Re: bug#59620: 29.0.50;
 Wrong global-mode-string position in tab-bar + emacs -nw
Date: Mon, 28 Nov 2022 14:58:51 +0200

> Cc: 59620 <at> debbugs.gnu.org
> From: Juri Linkov <juri <at> linkov.net>
> Date: Mon, 28 Nov 2022 09:54:17 +0200
> 
> >> Looks like tab-bar-format-align-right is evaluated with the wrong window
> >> being the selected one: it should use the tab-bar pseudo-window to do what
> >> you expect.
> >
> > I don't know what is the root cause, but it's a reasonable hypothesis.
> > Not sure why it only affects "emacs -nw", though.
> >
> > Do you know how to get the tab-bar pseudo-window?  It seems that
> > "f->tab_bar_window" it's not exposed from C to elisp.
> 
> Unless Eli can suggest how to fix `(space :align-to (- right (,hpos)))
> to work on TTY frames the same way as it works on GUI frames,
> I could try to rewrite it to avoid the keyword `right', i.e. to use
> `(space :align-to (,hpos-from-left)) where hpos-from-left could be
> calculated by using string-pixel-width on the text from the left side.

I replied without paying attention to the -nw part, sorry.

On TTY frames the tab bar is not a window, so what I wrote is impossible,
and thus avoiding the 'right' part in the align-to spec is a good idea
regardless.

Message #20 received at 59620 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: gabriel376 <at> hotmail.com, 59620 <at> debbugs.gnu.org
Subject: Re: bug#59620: 29.0.50; Wrong global-mode-string position in
 tab-bar + emacs -nw
Date: Mon, 28 Nov 2022 19:29:38 +0200

[Message part 1 (text/plain, inline)]

> On TTY frames the tab bar is not a window, so what I wrote is impossible,
> and thus avoiding the 'right' part in the align-to spec is a good idea
> regardless.

Avoiding the 'right' part in align-to has such a drawback that while
resizing the frame the position of the aligned element is not updated
immediately.  It's updated only when display-time refreshes the time on
the tab bar.  The position relative to the right edge has no such problem.
So better to leave the 'right' part on GUI frames, and switch to counting
from the left only on TTY frames where frames are resized less often:

[tab-bar-format-align-right.patch (text/x-diff, inline)]

diff --git a/lisp/tab-bar.el b/lisp/tab-bar.el
index eb4cec48619..cabad9d7d5e 100644
--- a/lisp/tab-bar.el
+++ b/lisp/tab-bar.el
@@ -936,7 +936,10 @@ tab-bar-format-align-right
          (hpos (progn
                  (add-face-text-property 0 (length rest) 'tab-bar t rest)
                  (string-pixel-width rest)))
-         (str (propertize " " 'display `(space :align-to (- right (,hpos))))))
+         (str (propertize " " 'display
+                          (if window-system
+                              `(space :align-to (- right (,hpos)))
+                            `(space :align-to (,(- (frame-inner-width) hpos)))))))
     `((align-right menu-item ,str ignore))))
 
 (defun tab-bar-format-global ()

Message #23 received at 59620 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Juri Linkov <juri <at> linkov.net>
Cc: gabriel376 <at> hotmail.com, 59620 <at> debbugs.gnu.org
Subject: Re: bug#59620: 29.0.50; Wrong global-mode-string position in
 tab-bar + emacs -nw
Date: Mon, 28 Nov 2022 20:34:14 +0200

> From: Juri Linkov <juri <at> linkov.net>
> Cc: gabriel376 <at> hotmail.com,  59620 <at> debbugs.gnu.org
> Date: Mon, 28 Nov 2022 19:29:38 +0200
> 
> Avoiding the 'right' part in align-to has such a drawback that while
> resizing the frame the position of the aligned element is not updated
> immediately.  It's updated only when display-time refreshes the time on
> the tab bar.  The position relative to the right edge has no such problem.
> So better to leave the 'right' part on GUI frames, and switch to counting
> from the left only on TTY frames where frames are resized less often:

That would require you to make sure this code always runs in the context of
the tab-bar (pseudo)window.  If that can be ensured, fine.

Message #28 received at 59620-done <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: gabriel376 <at> hotmail.com, 59620-done <at> debbugs.gnu.org
Subject: Re: bug#59620: 29.0.50; Wrong global-mode-string position in
 tab-bar + emacs -nw
Date: Fri, 02 Dec 2022 09:59:57 +0200

>> Avoiding the 'right' part in align-to has such a drawback that while
>> resizing the frame the position of the aligned element is not updated
>> immediately.  It's updated only when display-time refreshes the time on
>> the tab bar.  The position relative to the right edge has no such problem.
>> So better to leave the 'right' part on GUI frames, and switch to counting
>> from the left only on TTY frames where frames are resized less often:
>
> That would require you to make sure this code always runs in the context of
> the tab-bar (pseudo)window.  If that can be ensured, fine.

Since this can't be ensured, I pushed a simpler patch to emacs-29,
and closed.

Message #31 received at 59620-done <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Juri Linkov <juri <at> linkov.net>
Cc: gabriel376 <at> hotmail.com, 59620-done <at> debbugs.gnu.org
Subject: Re: bug#59620: 29.0.50; Wrong global-mode-string position in
 tab-bar + emacs -nw
Date: Fri, 02 Dec 2022 17:01:56 +0200

> From: Juri Linkov <juri <at> linkov.net>
> Cc: gabriel376 <at> hotmail.com,  59620-done <at> debbugs.gnu.org
> Date: Fri, 02 Dec 2022 09:59:57 +0200
> 
> > That would require you to make sure this code always runs in the context of
> > the tab-bar (pseudo)window.  If that can be ensured, fine.
> 
> Since this can't be ensured, I pushed a simpler patch to emacs-29,
> and closed.

Thanks, but I think the code needs to use window-system the function, not
the variable, so that you could ask about the currently-selected frame.  We
generally don't want to use window-system the variable too much.

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