master 5480d02cc5: Preserve echo area message when running DND mouse movement function

[Po Lu]

branch: master
commit 5480d02cc56bb787f6cd1f81bb1626793f6e1247
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Preserve echo area message when running DND mouse movement function
    
    * lisp/term/x-win.el (x-dnd-movement): Stop redisplaying here.
    * src/xterm.c (x_dnd_begin_drag_and_drop): Redisplay with the
    echo area preserved.
---
 lisp/term/x-win.el | 3 +--
 src/xterm.c        | 5 +++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/lisp/term/x-win.el b/lisp/term/x-win.el
index 3a0bd65f29..55fe11a097 100644
--- a/lisp/term/x-win.el
+++ b/lisp/term/x-win.el
@@ -1568,8 +1568,7 @@ frames on all displays."
 
 (defun x-dnd-movement (_frame position)
   "Handle movement to POSITION during drag-and-drop."
-  (dnd-handle-movement position)
-  (redisplay))
+  (dnd-handle-movement position))
 
 (defun x-device-class (name)
   "Return the device class of NAME.
diff --git a/src/xterm.c b/src/xterm.c
index 53c640ca6c..0436d3c00c 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -11779,6 +11779,11 @@ x_dnd_begin_drag_and_drop (struct frame *f, Time time, 
Atom xaction,
                         Fposn_at_x_y (x, y, frame_object, Qnil));
                  x_dnd_unwind_flag = false;
                  unbind_to (ref, Qnil);
+
+                 /* Redisplay this way to preserve the echo area.
+                    Otherwise, the contents will abruptly disappear
+                    when the mouse moves over a frame.  */
+                 redisplay_preserve_echo_area (33);
                }
            }