From f45a776fe3c9160c49fdf21a96d37d2ed780836c Mon Sep 17 00:00:00 2001
From: shipmints <shipmints@gmail.com>
Date: Thu, 30 Jan 2025 12:57:00 -0500
Subject: [PATCH] Add new variable tab-bar-format-tab-help-text-function

* lisp/tab-bar.el (tab-bar--format-tab):
Add new variable 'tab-bar-format-tab-help-text-function' and a default
function 'tab-bar-format-tab-help-text-default'.  'tab-bar--format-tab'
respects this new variable when producing a tab's help text, normally
shown in the echo area or via tooltips (bug#75950).
---
 etc/NEWS        |  7 +++++++
 lisp/tab-bar.el | 15 +++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 7f6084490d8..2b1951c7b0b 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -256,6 +256,13 @@ This is useful to avoid key binding conflicts, such as when folding in
 outline mode using TAB keys, or when a user wants to define her own
 tab-bar keys without first having to remove the defaults.
 
+---
+*** New variable 'tab-bar-format-tab-help-text-function'.
+This variable may be overridden with a user-provided function to
+customize help text for tabs displayed on the tab-bar.  Help text is
+normally shown in the echo area or via tooltips.  See the variable's
+docstring for arguments passed to a help-text function.
+
 ** Project
 
 ---
diff --git a/lisp/tab-bar.el b/lisp/tab-bar.el
index 85a1bb59dc8..4b676ca89da 100644
--- a/lisp/tab-bar.el
+++ b/lisp/tab-bar.el
@@ -992,6 +992,17 @@ You can hide these buttons by customizing `tab-bar-format' and removing
        menu-item ,tab-bar-forward-button tab-bar-history-forward
        :help "Click to go forward in tab history"))))
 
+(defun tab-bar-format-tab-help-text-default (tab _i)
+  (alist-get 'name tab))
+
+(defvar tab-bar-format-tab-help-text-function #'tab-bar-format-tab-help-text-default
+  "Function to produce help text for tabs displayed in the tab bar.
+This function should accept two arguments: the tab, and the one-based
+tab's number.
+
+The function should produce a string, which may be propertized.  By
+default, use function `tab-bar-format-tab-help-text-default.")
+
 (defun tab-bar--format-tab (tab i)
   "Format TAB using its index I and return the result as a keymap."
   (append
@@ -1002,13 +1013,13 @@ You can hide these buttons by customizing `tab-bar-format' and removing
         menu-item
         ,(funcall tab-bar-tab-name-format-function tab i)
         ignore
-        :help ,(alist-get 'name tab))))
+        :help ,(funcall tab-bar-format-tab-help-text-function tab i))))
     (t
      `((,(intern (format "tab-%i" i))
         menu-item
         ,(funcall tab-bar-tab-name-format-function tab i)
         ,(alist-get 'binding tab)
-        :help ,(alist-get 'name tab)))))
+        :help ,(funcall tab-bar-format-tab-help-text-function tab i)))))
    (when (alist-get 'close-binding tab)
      `((,(if (eq (car tab) 'current-tab) 'C-current-tab
            (intern (format "C-tab-%i" i)))