master 510eb1d401 2/2: Fix error when calling DND movement tracking function

[Po Lu]

branch: master
commit 510eb1d401b5708657819913a52a3d8ba2dc0f3f
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix error when calling DND movement tracking function
    
    * src/xterm.c (x_dnd_begin_drag_and_drop): Verify
    x_dnd_movement_x and x_dnd_movement_y are wholenums before
    caling posn-at-x-y.
---
 src/xterm.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/xterm.c b/src/xterm.c
index f5770ad7e7..57a64cb5d1 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -9540,7 +9540,12 @@ x_dnd_begin_drag_and_drop (struct frame *f, Time time, 
Atom xaction,
          x_dnd_movement_frame = NULL;
 
          if (!NILP (Vx_dnd_movement_function)
-             && !FRAME_TOOLTIP_P (XFRAME (frame_object)))
+             && !FRAME_TOOLTIP_P (XFRAME (frame_object))
+             && x_dnd_movement_x >= 0
+             && x_dnd_movement_y >= 0
+             && x_dnd_frame
+             && (XFRAME (frame_object) != x_dnd_frame
+                 || x_dnd_allow_current_frame))
            {
              x_dnd_old_window_attrs = root_window_attrs;
              x_dnd_unwind_flag = true;