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

[Juri Linkov]

>> Sorry, I don't understand what I should do in tab-bar-mode
>> for quit-restore-window.  I expected that changes should be
>> in window.el.
>
> Provide an option, say 'tab-bar-save-frame', that allows users to
> customize whether a frame should be deleted when "other tabs are
> available for that frame".  And provide a function, say
> 'tab-bar-save-frame-p', 'window--delete' could call thusly

Ok, here is a better patch:

diff --git a/lisp/window.el b/lisp/window.el
index 2208346ec8c..abc9f1b4011 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -4968,6 +4968,10 @@ frame-auto-hide-function
   :group 'frames
   :version "26.1")
 
+(defvar window-delete-frame-predicate-functions nil
+  "Don't delete frame when one of functions returns t.
+Called with two arguments: FRAME and KILL.")
+
 (defun window--delete (&optional window dedicated-only kill)
   "Delete WINDOW if possible.
 WINDOW must be a live window and defaults to the selected one.
@@ -4982,6 +4986,10 @@ window--delete
        ((eq deletable 'frame)
        (let ((frame (window-frame window)))
          (cond
+          ((run-hook-with-args-until-success
+            'window-delete-frame-predicate-functions
+            frame kill)
+           nil)
           (kill
            (delete-frame frame))
            ((functionp (frame-parameter frame 'auto-hide-function))
diff --git a/lisp/tab-bar.el b/lisp/tab-bar.el
index dac57ce2070..25bfefbc205 100644
--- a/lisp/tab-bar.el
+++ b/lisp/tab-bar.el
@@ -2631,6 +2631,14 @@ tab-switcher-mouse-select
   (goto-char (posn-point (event-end event)))
   (tab-switcher-select))
 
+
+(defun tab-bar-window-delete-frame-p (frame _kill)
+  "Whether FRAME should be deleted when other tabs are available for that 
frame.
+Used via `window-delete-frame-predicate-functions' by `window--delete'."
+  (and tab-bar-mode (> (length (funcall tab-bar-tabs-function frame)) 1)))
+
+(add-hook 'window-delete-frame-predicate-functions 
#'tab-bar-window-delete-frame-p)
+
 
 (defun tab-bar--reusable-frames (all-frames)
   (cond