bug#51247: 28.0.60; Insufficient documentation of tab-bar.el internal functions

[Eli Zaretskii <eliz@gnu.org>]

> From: Juri Linkov <juri@linkov.net>
> Cc: 51247@debbugs.gnu.org
> Date: Sun, 17 Oct 2021 21:29:21 +0300
> 
> >>   [ ] tab-bar-format-tabs
> >>           Show all tabs.
> >>   [X] tab-bar-format-tabs-groups
> >>           Show tabs with their groups.
> >>   [ ] tab-bar-separator
> >>           Separator between tabs.
> >>   [ ] tab-bar-format-add-tab
> >>           Button to add a new tab.
> >>   [X] tab-bar-format-align-right
> >>           Align the rest of tab bar items to the right.
> >>   [X] tab-bar-format-global
> >>           Format ‘global-mode-string’ to display it in the tab bar. More
> >>   [INS]
> >>
> >> So here its docstring explains what this option is useful for.
> >
> > Can't you provide a separate text for the Custom display?  The doc
> > string in its current form is simply misleading.
> 
> It's a feature of :options in defcustom that it takes the text
> from the docstrings.  Maybe it's possible to override this text,
> but I currently don't know how.

OK, how about the patch below?

diff --git a/lisp/tab-bar.el b/lisp/tab-bar.el
index 82ec617..3dc95c9 100644
--- a/lisp/tab-bar.el
+++ b/lisp/tab-bar.el
@@ -705,11 +705,14 @@ tab-bar-format
   "Template for displaying tab bar items.
 Every item in the list is a function that returns
 a string, or a list of menu-item elements, or nil.
-When you add more items `tab-bar-format-align-right' and
-`tab-bar-format-global' to the end, then after enabling
-`display-time-mode' (or any other mode that uses `global-mode-string')
-it will display time aligned to the right on the tab bar instead of
-the mode line.  Replacing `tab-bar-format-tabs' with
+Adding a function to the list causes the tab bar to show
+that string, or display a menu with those menu items when
+you click on the tab bar.
+If the list ends with `tab-bar-format-align-right' and
+`tab-bar-format-global', then after enabling `display-time-mode'
+(or any other mode that uses `global-mode-string'),
+it will display time aligned to the right on the tab bar instead
+of the mode line.  Replacing `tab-bar-format-tabs' with
 `tab-bar-format-tabs-groups' will group tabs on the tab bar."
   :type 'hook
   :options '(tab-bar-format-menu-global
@@ -728,7 +731,7 @@ tab-bar-format
   :version "28.1")
 
 (defun tab-bar-format-menu-global ()
-  "Show global menu on clicking the Menu button."
+  "Produce the Menu button for the tab bar that shows a global menu."
   `((add-tab menu-item (propertize "Menu" 'face 'tab-bar-tab-inactive)
              (lambda (event) (interactive "e")
                (let ((menu (make-sparse-keymap
@@ -745,7 +748,8 @@ tab-bar-format-menu-global
              :help "Global Menu")))
 
 (defun tab-bar-format-history ()
-  "Show back and forward buttons when `tab-bar-history-mode' is enabled.
+  "Produce back and forward buttons for the tab bar.
+These buttons will be shown when `tab-bar-history-mode' is enabled.
 You can hide these buttons by customizing `tab-bar-format' and removing
 `tab-bar-format-history' from it."
   (when tab-bar-history-mode
@@ -781,7 +785,7 @@ tab-bar--format-tab
         ,(alist-get 'close-binding tab))))))
 
 (defun tab-bar-format-tabs ()
-  "Show all tabs."
+  "Produce all the tabs for the tab bar."
   (let ((i 0))
     (mapcan
      (lambda (tab)
@@ -855,7 +859,7 @@ tab-bar--format-tab-group
       :help "Click to visit group"))))
 
 (defun tab-bar-format-tabs-groups ()
-  "Show tabs with their groups."
+  "Produce tabs for the tab bar grouped according to their groups."
   (let* ((tabs (funcall tab-bar-tabs-function))
          (current-group (funcall tab-bar-tab-group-function
                                  (tab-bar--current-tab-find tabs)))
@@ -899,7 +903,7 @@ tab-bar-format-align-right
     `((align-right menu-item ,str ignore))))
 
 (defun tab-bar-format-global ()
-  "Format `global-mode-string' to display it in the tab bar.
+  "Produce display of `global-mode-string' in the tab bar.
 When `tab-bar-format-global' is added to `tab-bar-format'
 (possibly appended after `tab-bar-format-align-right'),
 then modes that display information on the mode line