bug#71386: 29.1; Frame is auto-deleted even when it has multiple tabs

[Juri Linkov]

> +(defvar window-delete-frame-functions nil
> +  "A list of functions to handle the frame deletion.
>
> I'd still prefer a tab-bar specific option (like 'tab-bar-save-frame-p'
> as mentioned earlier) for two reasons.
>
> The first reason is that 'window--delete' is an internal function of
> window.el.  I wouldn't want an internal function run a hook "of its own"
> because that's difficult to explain to users.  OTOH I suppose that a
> function like 'tab-bar-save-frame-p' should be callable from any other
> function too, as soon as the need arises.
>
> The second reason is that I wouldn't want "anyone" to inhibit frame
> deletion.  Such a facility could have consequences I cannot fathom at
> the moment.  Would we want 'delete-frame' to obey it too and possibly
> spare the frame?

Ok, here is the right patch:

diff --git a/lisp/window.el b/lisp/window.el
index b7bd59bc813..872110a8321 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -4120,6 +4120,8 @@ window-deletable-p
 
   (let ((frame (window-frame window)))
     (cond
+     ((and tab-bar-mode (> (length (funcall tab-bar-tabs-function frame)) 1))
+      'tab)
      ((frame-root-window-p window)
       ;; WINDOW's frame can be deleted only if there are other frames
       ;; on the same terminal, and it does not contain the active
@@ -4979,6 +4981,9 @@ window--delete
   (unless (and dedicated-only (not (window-dedicated-p window)))
     (let ((deletable (window-deletable-p window)))
       (cond
+       ((eq deletable 'tab)
+        (tab-bar-close-tab)
+        'tab)
        ((eq deletable 'frame)
        (let ((frame (window-frame window)))
          (cond