Allow minibuffer to stay in its original frame. Tidy up this area.

* doc/emacs/mini.texi (Basic Minibuffer): Add an entry for
minibuffer-follows-selected-frame.

* doc/lispref/minibuf.texi (Minibuffer Misc): Describe the new parameter to
minibufferp, LIVE.

* etc/NEWS: Add an entry describing the new minibuffer strategy.

* lisp/cus-start.el (minibuffer-prompt-properties--setter): Add an entry for
minibuffer-follows-selected-frame.

* lisp/minibuffer.el (minibuffer-message): Check for the current buffer being
an _active_ minibuffer rather than merely a minibuffer.

* src/frame.c (do_switch_frame): Call move_minibuffer_onto_frame.

* src/lisp.h (Top level): Add prototypes for move_minibuffer_onto_frame and
is_minibuffer.

* src/minibuf.c (minibuf_follows_frame): New function which ignores local and
let-bound values of minibuffer-follows-selected-frame.
(choose_minibuf_frame): Reformulate this function to reuse a minibuffer window
where possible, and to ensure no other frame has its minibuffer current, but
only when `minibuffer-follows-selected-frame'.
(move_minibuffer_onto_frame): New function.
(live_minibuffer_p): New function.
(Fminibufferp): Add a new &optional parameter LIVE.  Reformulate, possibly
calling live_minibuffer_p.
(read_minibuf): move the incrementation of minibuf_level to before the call of
choose_minibuf_frame.  Empty the miniwindows of frames without an active
minibuffer, rather than of all but the current frame.
(is_minibuffer): New function.
(read_minibuf_unwind): Note the miniwindow being restored and resize all other
miniwindows to zero size.
(minibuffer-follows-selected-frame): New configuration variable.

* src/window.c (candidate_window_p): In some scenarios, check the miniwindow
holds an active minibuffer.

* src/xdisp.c (get_window_cursor_type): Suppress the cursor for non-active
miniwindows, regardless of minibuf_level.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/window.c b/src/window.c
index e7433969d29..a6de34f3db6 100644
--- a/src/window.c
+++ b/src/window.c
@@ -2643,8 +2643,10 @@ candidate_window_p (Lisp_Object window, Lisp_Object owindow,
     /* 	To qualify as candidate, it's not sufficient for WINDOW's frame
 	to just share the minibuffer window - it must be active as well
 	(see Bug#24500).  */
-    candidate_p = (EQ (XWINDOW (all_frames)->frame, w->frame)
-		   || EQ (XWINDOW (all_frames)->frame, FRAME_FOCUS_FRAME (f)));
+    candidate_p = ((EQ (XWINDOW (all_frames)->frame, w->frame)
+                    || (EQ (f->minibuffer_window, all_frames)
+                        && EQ (XWINDOW (all_frames)->frame, FRAME_FOCUS_FRAME (f))))
+                   && !is_minibuffer (0, XWINDOW (all_frames)->contents));
   else if (FRAMEP (all_frames))
     candidate_p = EQ (all_frames, w->frame);