Provide new option `delete-window-set-selected' (Bug#47300)

When `delete-window' deletes its frame's selected window, this new
option allows to choose another window as replacement.

* lisp/window.el (get-lru-window, get-mru-window)
(get-largest-window): New optional argument NO-OTHER.
(window-at-pos): New function.
(delete-window-set-selected): New option.
(delete-window): Handle `delete-window-set-selected'.
* src/window.c (Fdelete_window_internal): Set the selected
window of WINDOW's frame to the first window on that frame and
let `delete-window' choose a more suitable window instead.
* doc/lispref/windows.texi (Deleting Windows): Describe new
option `delete-window-set-selected'.
(Cyclic Window Ordering): Describe new NO-OTHER argument for
`get-lru-window', `get-mru-window' and `get-largest-window'.
* etc/NEWS: Mention `delete-window-set-selected' and the NO-OTHER
argument.

1 files changed, 4 insertions, 21 deletions

diff --git a/src/window.c b/src/window.c
index 2d98ae5f156..db324effcce 100644
--- a/src/window.c
+++ b/src/window.c
@@ -5148,15 +5148,13 @@ Signal an error when WINDOW is the only window on its frame.  */)
       adjust_frame_glyphs (f);
 
       if (!WINDOW_LIVE_P (FRAME_SELECTED_WINDOW (f)))
-        /* We deleted the frame's selected window.  */
+        /* We apparently deleted the frame's selected window; use the
+           frame's first window as substitute but don't record it yet.
+           `delete-window' may have something better up its sleeves.  */
         {
           /* Use the frame's first window as fallback ...  */
           Lisp_Object new_selected_window = Fframe_first_window (frame);
-          /* ... but preferably use its most recently used window.  */
-          Lisp_Object mru_window;
 
-          /* `get-mru-window' might fail for some reason so play it safe
-          - promote the first window _without recording it_ first.  */
           if (EQ (FRAME_SELECTED_WINDOW (f), selected_window))
             Fselect_window (new_selected_window, Qt);
           else
@@ -5164,24 +5162,9 @@ Signal an error when WINDOW is the only window on its frame.  */)
                last selected window on F was an active minibuffer, we
                want to return to it on a later Fselect_frame.  */
             fset_selected_window (f, new_selected_window);
-
-          unblock_input ();
-
-          /* Now look whether `get-mru-window' gets us something.  */
-          mru_window = call1 (Qget_mru_window, frame);
-          if (WINDOW_LIVE_P (mru_window)
-              && EQ (XWINDOW (mru_window)->frame, frame))
-            new_selected_window = mru_window;
-
-          /* If all ended up well, we now promote the mru window.  */
-          if (EQ (FRAME_SELECTED_WINDOW (f), selected_window))
-            Fselect_window (new_selected_window, Qnil);
-          else
-            fset_selected_window (f, new_selected_window);
         }
-      else
-        unblock_input ();
 
+      unblock_input ();
       FRAME_WINDOW_CHANGE (f) = true;
     }
   else