bug#58862: 29.0.50; tab-bar-mode doesn't display after display-time-mode with format option

bug#58862: 29.0.50; tab-bar-mode doesn't display after display-time-mode with format option

[Stefan Kangas]

Severity: minor

In emacs -Q:

    0. Evaluate
           (setq tab-bar-format '(tab-bar-format-global))
    1. M-x tab-bar-mode RET
    2. M-x display-time-mode RET

The tab bar is not visible.  I expect that it is, just as when I do
this:

    (progn
       (setq tab-bar-format '(tab-bar-format-global))
       (tab-bar-mode 1)
       (display-time-mode 1))

In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.34, cairo version 1.16.0) of 2022-10-25 built on joffe
Repository revision: 9bfe00dda6b59d9b93eb7a825f6e0868afa1cca3
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Debian GNU/Linux bookworm/sid

Configured using:
 'configure --with-native-compilation'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES
NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3
THREADS TIFF TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

bug#58862: 29.0.50; tab-bar-mode doesn't display after display-time-mode with format option

[Juri Linkov]

> Severity: minor
>
> In emacs -Q:
>
>     0. Evaluate
>            (setq tab-bar-format '(tab-bar-format-global))
>     1. M-x tab-bar-mode RET
>     2. M-x display-time-mode RET
>
> The tab bar is not visible.  I expect that it is, just as when I do
> this:
>
>     (progn
>        (setq tab-bar-format '(tab-bar-format-global))
>        (tab-bar-mode 1)
>        (display-time-mode 1))

The tab bar is not visible because an empty tab bar can't be displayed:

  (tab-bar-format-list tab-bar-format)
  => ((global menu-item "" ignore))

So it works fine when you change the initialization order to:

    0. Evaluate
           (setq tab-bar-format '(tab-bar-format-global))
    1. M-x display-time-mode RET
    2. M-x tab-bar-mode RET

bug#58862: 29.0.50; tab-bar-mode doesn't display after display-time-mode with format option

[Stefan Kangas]

Juri Linkov <juri@linkov.net> writes:

>> Severity: minor
>>
>> In emacs -Q:
>>
>>     0. Evaluate
>>            (setq tab-bar-format '(tab-bar-format-global))
>>     1. M-x tab-bar-mode RET
>>     2. M-x display-time-mode RET
>>
>> The tab bar is not visible.  I expect that it is, just as when I do
>> this:
>>
>>     (progn
>>        (setq tab-bar-format '(tab-bar-format-global))
>>        (tab-bar-mode 1)
>>        (display-time-mode 1))
>
> The tab bar is not visible because an empty tab bar can't be displayed:
>
>   (tab-bar-format-list tab-bar-format)
>   => ((global menu-item "" ignore))
>
> So it works fine when you change the initialization order to:
>
>     0. Evaluate
>            (setq tab-bar-format '(tab-bar-format-global))
>     1. M-x display-time-mode RET
>     2. M-x tab-bar-mode RET

Sorry for the late reply here.  I guess what surprised me is that the
order mattered here.  If you don't think this is a bug, we can close
this.  Thanks.

bug#58862: 29.0.50; tab-bar-mode doesn't display after display-time-mode with format option

[Juri Linkov]

tags 58862 notabug
close 58862 29.0.50
thanks

>> The tab bar is not visible because an empty tab bar can't be displayed:
>>
>>   (tab-bar-format-list tab-bar-format)
>>   => ((global menu-item "" ignore))
>>
>> So it works fine when you change the initialization order to:
>>
>>     0. Evaluate
>>            (setq tab-bar-format '(tab-bar-format-global))
>>     1. M-x display-time-mode RET
>>     2. M-x tab-bar-mode RET
>
> Sorry for the late reply here.  I guess what surprised me is that the
> order mattered here.  If you don't think this is a bug, we can close
> this.  Thanks.

I really have no idea how to display an empty tab-bar.
Fortunately, this is not a frequent problem, just need
to be careful not to enable tab-bar-mode when
the tab-bar is empty.  But when someone will get
an idea how to handle it, this could be reopened.

bug#58862: 29.0.50; tab-bar-mode doesn't display after display-time-mode with format option

[Stefan Kangas]

Juri Linkov <juri@linkov.net> writes:

> I really have no idea how to display an empty tab-bar.
> Fortunately, this is not a frequent problem, just need
> to be careful not to enable tab-bar-mode when
> the tab-bar is empty.  But when someone will get
> an idea how to handle it, this could be reopened.

Sounds good to me, and thanks for taking the time to explain things.