bug#51648: 28.0.60; `tab-bar-close-button' and `tab-bar-new-button' should be documented in the manual

[Juri Linkov <juri@linkov.net>]

> Well, the request was to allow customization of the image on the tabs,
> so maybe have just the image(s) customizable?

I noticed that in addition that the button for tab-bar-format-menu-bar
is not customizable, it also has a bug:

  `((menu-bar menu-item (propertize "Menu" 'face 'tab-bar-tab-inactive)
     tab-bar-menu-bar :help "Menu Bar")))
 
i.e. the part with (propertize "Menu" 'face 'tab-bar-tab-inactive)
is inside the quoted list, but it should be unquoted with `,'.

If it's ok to leave this bug in the release branch,
then maybe this patch should be applied only to master?

diff --git a/lisp/tab-bar.el b/lisp/tab-bar.el
index d49fc2efea..4c95438bae 100644
--- a/lisp/tab-bar.el
+++ b/lisp/tab-bar.el
@@ -751,9 +751,13 @@ tab-bar-menu-bar
                 (menu-bar-keymap))
     (popup-menu menu event)))
 
+(defvar tab-bar-menu-bar-button
+  (propertize "Menu" 'face 'tab-bar-tab-inactive)
+  "Button for the menu bar.")
+
 (defun tab-bar-format-menu-bar ()
   "Produce the Menu button for the tab bar that shows the menu bar."
-  `((menu-bar menu-item (propertize "Menu" 'face 'tab-bar-tab-inactive)
+  `((menu-bar menu-item ,tab-bar-menu-bar-button
      tab-bar-menu-bar :help "Menu Bar")))
 
--