Fix bug#64152 (Minibuffer sometimes goes "modal")

In particular, when a frame has no minibuffer and is using that
of a different "normal" frame, C-x 5 o, etc., and GUI
operations fail.

Fix by partially reverting the commit from 2022-07-07 15:38:09
+0000 "Remove obscure, obsolete code from do_switch_frame".  As
a consequent change, also revert the commit from 2022-07-08
20:19:03 +0000 "Remove now unused parameter TRACK from
do_switch_frame".

* src/frame.c (do_switch_frame): Restore the TRACK parameter.
Restore the code which redirects the frame focus when a new
frame gets selected.

* src/frame.c (Fselect_frame, Fhandle_switch_frame)
(delete_frame)
* src/keyboard.c (quit_throw_to_read_char)
* src/lisp.h (do_switch_frame prototype)
* src/minibuf.c (read_minibuf_unwind)
* src/window.c (Fset_window_configuration): Restore the TRACK
argument to do_switch_frame.

* src/xterm.c (x_try_restore_frame): Add a zero TRACK argument
to do_switch_frame.

1 files changed, 46 insertions, 4 deletions

diff --git a/src/frame.c b/src/frame.c
index 38a6583605c..fc6a3459482 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -1444,6 +1444,10 @@ affects all frames on the same terminal device.  */)
    If FRAME is a switch-frame event `(switch-frame FRAME1)', use
    FRAME1 as frame.
 
+   If TRACK is non-zero and the frame that currently has the focus
+   redirects its focus to the selected frame, redirect that focused
+   frame's focus to FRAME instead.
+
    FOR_DELETION non-zero means that the selected frame is being
    deleted, which includes the possibility that the frame's terminal
    is dead.
@@ -1451,7 +1455,7 @@ affects all frames on the same terminal device.  */)
    The value of NORECORD is passed as argument to Fselect_window.  */
 
 Lisp_Object
-do_switch_frame (Lisp_Object frame, int for_deletion, Lisp_Object norecord)
+do_switch_frame (Lisp_Object frame, int track, int for_deletion, Lisp_Object norecord)
 {
   struct frame *sf = SELECTED_FRAME (), *f;
 
@@ -1473,6 +1477,44 @@ do_switch_frame (Lisp_Object frame, int for_deletion, Lisp_Object norecord)
   else if (f == sf)
     return frame;
 
+  /* If the frame with GUI focus has had it's Emacs focus redirected
+     toward the currently selected frame, we should change the
+     redirection to point to the newly selected frame.  This means
+     that if the focus is redirected from a minibufferless frame to a
+     surrogate minibuffer frame, we can use `other-window' to switch
+     between all the frames using that minibuffer frame, and the focus
+     redirection will follow us around.  This code is necessary when
+     we have a minibufferless frame using the MB in another (normal)
+     frame (bug#64152) (ACM, 2023-06-20).  */
+#ifdef HAVE_WINDOW_SYSTEM
+  if (track && FRAME_WINDOW_P (f) && FRAME_TERMINAL (f)->get_focus_frame)
+    {
+      Lisp_Object gfocus; /* The frame which still has focus on the
+			     current terminal, according to the GUI
+			     system. */
+      Lisp_Object focus;  /* The frame to which Emacs has redirected
+			     the focus from `gfocus'.  This might be a
+			     frame with a minibuffer when `gfocus'
+			     doesn't have a MB.  */
+
+      gfocus = FRAME_TERMINAL (f)->get_focus_frame (f);
+      if (FRAMEP (gfocus))
+	{
+	  focus = FRAME_FOCUS_FRAME (XFRAME (gfocus));
+	  if (FRAMEP (focus) && XFRAME (focus) == SELECTED_FRAME ())
+	      /* Redirect frame focus also when FRAME has its minibuffer
+		 window on the selected frame (see Bug#24500).
+
+		 Don't do that: It causes redirection problem with a
+		 separate minibuffer frame (Bug#24803) and problems
+		 when updating the cursor on such frames.
+	      || (NILP (focus)
+		  && EQ (FRAME_MINIBUF_WINDOW (f), sf->selected_window)))  */
+	    Fredirect_frame_focus (gfocus, frame);
+	}
+    }
+#endif /* HAVE_X_WINDOWS */
+
   if (!for_deletion && FRAME_HAS_MINIBUF_P (sf))
     resize_mini_window (XWINDOW (FRAME_MINIBUF_WINDOW (sf)), 1);
 
@@ -1574,7 +1616,7 @@ This function returns FRAME, or nil if FRAME has been deleted.  */)
     /* Do not select a tooltip frame (Bug#47207).  */
     error ("Cannot select a tooltip frame");
   else
-    return do_switch_frame (frame, 0, norecord);
+    return do_switch_frame (frame, 1, 0, norecord);
 }
 
 DEFUN ("handle-switch-frame", Fhandle_switch_frame,
@@ -1590,7 +1632,7 @@ necessarily represent user-visible input focus.  */)
   kset_prefix_arg (current_kboard, Vcurrent_prefix_arg);
   run_hook (Qmouse_leave_buffer_hook);
 
-  return do_switch_frame (event, 0, Qnil);
+  return do_switch_frame (event, 0, 0, Qnil);
 }
 
 DEFUN ("selected-frame", Fselected_frame, Sselected_frame, 0, 0, 0,
@@ -2108,7 +2150,7 @@ delete_frame (Lisp_Object frame, Lisp_Object force)
 	Fraise_frame (frame1);
 #endif
 
-      do_switch_frame (frame1, 1, Qnil);
+      do_switch_frame (frame1, 0, 1, Qnil);
       sf = SELECTED_FRAME ();
     }
   else