In attempted recursive minibuffer use, display error message in correct frame

This was problematic when minibuffer-follows-selected-frame was non-nil.
Introduce a new parameter DONT-SET-FRAME to set-window-configuration.

* doc/lispref/windows.texi (Window Configurations): Describe the new &optional
parameter to set-window-configuration.

* etc/NEWS (Lisp Changes): Note the new parameter to set-window-configuration.

* src/keyboard.c (read_char_help_form_unwind): Add a new Qnil argument to the
call of Fset_window_configuration.

* src/minibuf.c (read_minibuf): Cons up a Qt with the window configuration in
the argument to record_unwind_protect for the window configuration (twice).

* src/window.c (Fset_window_configuration): Add the new &optional parameter
and document it in the doc string.  At the final do_switch_frame operation,
restore the original frame when DONT-SET-FRAME is non-nil.
(restore_window_configuration): Handle the new parameter when the supplied
argument is a cons.

3 files changed, 20 insertions, 8 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index 49a0a8bd236..1579c007ecf 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -2122,7 +2122,7 @@ read_char_help_form_unwind (void)
   Lisp_Object window_config = XCAR (help_form_saved_window_configs);
   help_form_saved_window_configs = XCDR (help_form_saved_window_configs);
   if (!NILP (window_config))
-    Fset_window_configuration (window_config);
+    Fset_window_configuration (window_config, Qnil);
 }
 
 #define STOP_POLLING                                    \
diff --git a/src/minibuf.c b/src/minibuf.c
index c4adca15365..464e3018f7d 100644
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -501,14 +501,15 @@ read_minibuf (Lisp_Object map, Lisp_Object initial, Lisp_Object prompt,
   record_unwind_protect_void (choose_minibuf_frame);
 
   record_unwind_protect (restore_window_configuration,
-                         Fcurrent_window_configuration (Qnil));
+                         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))
     record_unwind_protect (restore_window_configuration,
-                           Fcurrent_window_configuration (mini_frame));
+                           Fcons (Qt,
+                                  Fcurrent_window_configuration (mini_frame)));
 
   /* If the minibuffer is on an iconified or invisible frame,
      make it visible now.  */
diff --git a/src/window.c b/src/window.c
index a6de34f3db6..6cd3122b43b 100644
--- a/src/window.c
+++ b/src/window.c
@@ -6824,19 +6824,25 @@ DEFUN ("window-configuration-frame", Fwindow_configuration_frame, Swindow_config
 }
 
 DEFUN ("set-window-configuration", Fset_window_configuration,
-       Sset_window_configuration, 1, 1, 0,
+       Sset_window_configuration, 1, 2, 0,
        doc: /* Set the configuration of windows and buffers as specified by CONFIGURATION.
 CONFIGURATION must be a value previously returned
 by `current-window-configuration' (which see).
+
+Normally, this function selects the frame of the CONFIGURATION, but if
+DONT-SET-FRAME is non-nil, it leaves selected the frame which was
+current at the start of the function.
+
 If CONFIGURATION was made from a frame that is now deleted,
 only frame-independent values can be restored.  In this case,
 the return value is nil.  Otherwise the value is t.  */)
-  (Lisp_Object configuration)
+  (Lisp_Object configuration, Lisp_Object dont_set_frame)
 {
   register struct save_window_data *data;
   struct Lisp_Vector *saved_windows;
   Lisp_Object new_current_buffer;
   Lisp_Object frame;
+  Lisp_Object old_frame = selected_frame;
   struct frame *f;
   ptrdiff_t old_point = -1;
   USE_SAFE_ALLOCA;
@@ -7153,7 +7159,10 @@ the return value is nil.  Otherwise the value is t.  */)
          select_window above totally superfluous; it still sets f's
          selected window.  */
       if (FRAME_LIVE_P (XFRAME (data->selected_frame)))
-        do_switch_frame (data->selected_frame, 0, 0, Qnil);
+        do_switch_frame (NILP (dont_set_frame)
+                         ? data->selected_frame
+                         : old_frame
+                         , 0, 0, Qnil);
     }
 
   FRAME_WINDOW_CHANGE (f) = true;
@@ -7187,11 +7196,13 @@ the return value is nil.  Otherwise the value is t.  */)
   return FRAME_LIVE_P (f) ? Qt : Qnil;
 }
 
-
 void
 restore_window_configuration (Lisp_Object configuration)
 {
-  Fset_window_configuration (configuration);
+  if (CONSP (configuration))
+    Fset_window_configuration (XCDR (configuration), XCAR (configuration));
+  else
+    Fset_window_configuration (configuration, Qnil);
 }