Subject: bug#45072: 28.0.50; Emacs switches other buffer back uncontrollably, if other window's buffer is changed by user during minibuffer editing

From: martin rudalics <[email-masked]>
Date: Wed, 9 Dec 2020 10:33:26 +0100

> Yes.  But maybe read-from-minibuffer-restore-windows would be even
 > better.

And `read-minibuffer-restore-windows' would be even shorter.  Attached.

martin
--- a/doc/lispref/minibuf.texi
+++ b/doc/lispref/minibuf.texi
@@ -458,6 +458,19 @@ Text from Minibuffer
 list is used in the prompt.
 @end defun

+@defvar read-minibuffer-restore-windows
+If this option is non-@code{nil} (the default), getting input from the
+minibuffer will restore, on exit, the window configurations of the frame
+where the minibuffer was entered from and, if it is different, the frame
+that owns the minibuffer window.  This means that if, for example, a
+user splits a window while getting input from the minibuffer on the same
+frame, that split will be undone when exiting the minibuffer.
+
+If this option is @code{nil}, no such restorations are done.  Hence, the
+window split mentioned above will persist after exiting the minibuffer.
+@end defvar
+
+
 @node Object from Minibuffer
 @section Reading Lisp Objects with the Minibuffer
 @cindex minibuffer input, reading lisp objects
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -500,19 +500,21 @@ read_minibuf (Lisp_Object map, Lisp_Object initial, Lisp_Object prompt,

   record_unwind_protect_void (choose_minibuf_frame);

-  record_unwind_protect (restore_window_configuration,
-                         Fcons (Qt, Fcurrent_window_configuration (Qnil)));
+  if (read_minibuffer_restore_windows)
+    record_unwind_protect (restore_window_configuration,
+			   Fcons (Qt, Fcurrent_window_configuration (Qnil)));

   /* If the minibuffer window is on a different frame, save that
      frame's configuration too.  */
   mini_frame = WINDOW_FRAME (XWINDOW (minibuf_window));
-  if (!EQ (mini_frame, selected_frame))
+
+  if (read_minibuffer_restore_windows && !EQ (mini_frame, selected_frame))
     record_unwind_protect (restore_window_configuration,
 			   Fcons (/* Arrange for the frame later to be
-                                     switched back to the calling
-                                     frame. */
-                                  Qnil,
-                                  Fcurrent_window_configuration (mini_frame)));
+				     switched back to the calling
+				     frame. */
+				  Qnil,
+				  Fcurrent_window_configuration (mini_frame)));

   /* If the minibuffer is on an iconified or invisible frame,
      make it visible now.  */
@@ -2186,6 +2188,15 @@ syms_of_minibuf (void)
 uses to hide passwords.  */);
   Vread_hide_char = Qnil;

+  DEFVAR_BOOL ("read-minibuffer-restore-windows", read_minibuffer_restore_windows,
+	       doc: /* Non-nil means restore window configurations on exit from minibuffer.
+If this is non-nil (the default), reading input with the minibuffer will
+restore, on exit, the window configurations of the frame where the
+minibuffer was entered from and, if it is different, the frame that owns
+the associated minibuffer window.  If this is nil, no such restorations
+are done.  */);
+  read_minibuffer_restore_windows = true;
+
   defsubr (&Sactive_minibuffer_window);
   defsubr (&Sset_minibuffer_window);
   defsubr (&Sread_from_minibuffer);