bug#45556: 27.1; Unexpected behavior of `tab-bar-show' variable

[Marcel Ventosa <mve1@runbox.com>]

Hello,

I may be misunderstanding the purpose of the `tab-bar-show' variable.


Expected behavior
=================

If tab-bar-show = 1, Tab Bar is not visible when less than two tabs are
available.

If tab-bar-show = nil, Tab Bar is never visible

If tab-bar-show = t, Tab Bar is always visible

In addition, I would like to be able to change the value of
tab-bar-show to toggle the visibility of the Tab Bar (I don't want to
disable the mode, only hide the Tab Bar).


Actual behavior and recipe
==========================

Run "emacs -q", switch to *scratch* and evaluate the following, in
order:

(tab-bar-mode)
;; tab bar is shown on top of buffer
(setq tab-bar-show 1)
;; no change. Maybe we need to toggle the mode to effect changes?
(tab-bar-mode 0)
;; bar disappears
(tab-bar-mode)
;; bar still reappears with only one tab
;; expected behavior: tab bar remains hidden because only one tab exists
(tab-bar-new-tab)
;; two tabs exist and are visible
(tab-bar-close-tab)
;; only one tab is left, tab bar is hidden
(tab-bar-mode)
;; turn mode off again
(setq tab-bar-show nil)
;; no bar should be visible if I turn tab-bar-mode on again
(tab-bar-mode)
;; tab bar is still visible even with the variable set to nil


Best regards,

Marcel


In GNU Emacs 27.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.22,
cairo version 1.17.3) of 2020-08-29 built on juergen
Windowing system distributor 'The X.Org Foundation', version
11.0.12010000 System Description: Arch Linux

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --with-x-toolkit=gtk3 --with-xft --with-wide-int
 --with-modules --with-cairo --with-harfbuzz 'CFLAGS=-march=x86-64
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Configured features:
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Important settings:
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Minor modes in effect:
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Load-path shadows:
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Memory information:
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