master d5c1fec6ab: Improve safety of DND when Emacs is connected to multiple displays

[Po Lu]

branch: master
commit d5c1fec6abf046dad5d7318d9c6fa3a9fae13dea
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Improve safety of DND when Emacs is connected to multiple displays
    
    * src/xterm.c (x_dnd_begin_drag_and_drop): Don't check movement
    frame unless we know it comes from the right display.
---
 src/xterm.c | 203 ++++++++++++++++++++++++++++++++----------------------------
 1 file changed, 110 insertions(+), 93 deletions(-)

diff --git a/src/xterm.c b/src/xterm.c
index 80d34c114d..74dfc10044 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -10035,116 +10035,133 @@ x_dnd_begin_drag_and_drop (struct frame *f, Time 
time, Atom xaction,
       unblock_input ();
       pending_signals = signals_were_pending;
 
-      if (x_dnd_movement_frame)
-       {
-         XSETFRAME (frame_object, x_dnd_movement_frame);
-         XSETINT (x, x_dnd_movement_x);
-         XSETINT (y, x_dnd_movement_y);
-         x_dnd_movement_frame = NULL;
-
-         if (!NILP (Vx_dnd_movement_function)
-             && !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;
-
-             ref = SPECPDL_INDEX ();
-             record_unwind_protect_ptr (x_dnd_cleanup_drag_and_drop, f);
-             call2 (Vx_dnd_movement_function, frame_object,
-                    Fposn_at_x_y (x, y, frame_object, Qnil));
-             x_dnd_unwind_flag = false;
-             unbind_to (ref, Qnil);
-           }
-       }
-
-      if (hold_quit.kind != NO_EVENT)
+      /* Ignore mouse movement from displays that aren't the DND
+        display.  */
+#ifndef USE_GTK
+      if (event_display == FRAME_DISPLAY_INFO (f))
        {
-         if (hold_quit.kind == SELECTION_REQUEST_EVENT)
+#endif
+         if (x_dnd_movement_frame)
            {
-             x_dnd_old_window_attrs = root_window_attrs;
-             x_dnd_unwind_flag = true;
-
-             ref = SPECPDL_INDEX ();
-             record_unwind_protect_ptr (x_dnd_cleanup_drag_and_drop, f);
-             x_handle_selection_event ((struct selection_input_event *) 
&hold_quit);
-             x_dnd_unwind_flag = false;
-             unbind_to (ref, Qnil);
-             continue;
+             XSETFRAME (frame_object, x_dnd_movement_frame);
+             XSETINT (x, x_dnd_movement_x);
+             XSETINT (y, x_dnd_movement_y);
+             x_dnd_movement_frame = NULL;
+
+             if (!NILP (Vx_dnd_movement_function)
+                 && !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;
+
+                 ref = SPECPDL_INDEX ();
+                 record_unwind_protect_ptr (x_dnd_cleanup_drag_and_drop, f);
+                 call2 (Vx_dnd_movement_function, frame_object,
+                        Fposn_at_x_y (x, y, frame_object, Qnil));
+                 x_dnd_unwind_flag = false;
+                 unbind_to (ref, Qnil);
+               }
            }
 
-         if (x_dnd_in_progress)
+         if (hold_quit.kind != NO_EVENT)
            {
-             if (x_dnd_last_seen_window != None
-                 && x_dnd_last_protocol_version != -1)
-               x_dnd_send_leave (f, x_dnd_last_seen_window);
-             else if (x_dnd_last_seen_window != None
-                      && !XM_DRAG_STYLE_IS_DROP_ONLY (x_dnd_last_motif_style)
-                      && x_dnd_last_motif_style != XM_DRAG_STYLE_NONE
-                      && x_dnd_motif_setup_p)
+             if (hold_quit.kind == SELECTION_REQUEST_EVENT)
                {
-                 dmsg.reason = XM_DRAG_REASON (XM_DRAG_ORIGINATOR_INITIATOR,
-                                               XM_DRAG_REASON_DROP_START);
-                 dmsg.byte_order = XM_BYTE_ORDER_CUR_FIRST;
-                 dmsg.timestamp = hold_quit.timestamp;
-                 dmsg.side_effects
-                   = XM_DRAG_SIDE_EFFECT (xm_side_effect_from_action 
(FRAME_DISPLAY_INFO (f),
-                                                                      
x_dnd_wanted_action),
-                                          XM_DROP_SITE_VALID,
-                                          xm_side_effect_from_action 
(FRAME_DISPLAY_INFO (f),
-                                                                      
x_dnd_wanted_action),
-                                          XM_DROP_ACTION_DROP_CANCEL);
-                 dmsg.x = 0;
-                 dmsg.y = 0;
-                 dmsg.index_atom = FRAME_DISPLAY_INFO (f)->Xatom_XdndSelection;
-                 dmsg.source_window = FRAME_X_WINDOW (f);
-
-                 x_dnd_send_xm_leave_for_drop (FRAME_DISPLAY_INFO (f), f,
-                                               x_dnd_last_seen_window,
-                                               hold_quit.timestamp);
-                 xm_send_drop_message (FRAME_DISPLAY_INFO (f), FRAME_X_WINDOW 
(f),
-                                       x_dnd_last_seen_window, &dmsg);
+                 x_dnd_old_window_attrs = root_window_attrs;
+                 x_dnd_unwind_flag = true;
+
+                 ref = SPECPDL_INDEX ();
+                 record_unwind_protect_ptr (x_dnd_cleanup_drag_and_drop, f);
+                 x_handle_selection_event ((struct selection_input_event *) 
&hold_quit);
+                 x_dnd_unwind_flag = false;
+                 unbind_to (ref, Qnil);
+                 continue;
                }
 
-             x_dnd_end_window = x_dnd_last_seen_window;
-             x_dnd_last_seen_window = None;
-             x_dnd_last_seen_toplevel = None;
-             x_dnd_in_progress = false;
-             x_dnd_frame = NULL;
-           }
+             if (x_dnd_in_progress)
+               {
+                 if (x_dnd_last_seen_window != None
+                     && x_dnd_last_protocol_version != -1)
+                   x_dnd_send_leave (f, x_dnd_last_seen_window);
+                 else if (x_dnd_last_seen_window != None
+                          && !XM_DRAG_STYLE_IS_DROP_ONLY 
(x_dnd_last_motif_style)
+                          && x_dnd_last_motif_style != XM_DRAG_STYLE_NONE
+                          && x_dnd_motif_setup_p)
+                   {
+                     dmsg.reason = XM_DRAG_REASON 
(XM_DRAG_ORIGINATOR_INITIATOR,
+                                                   XM_DRAG_REASON_DROP_START);
+                     dmsg.byte_order = XM_BYTE_ORDER_CUR_FIRST;
+                     dmsg.timestamp = hold_quit.timestamp;
+                     dmsg.side_effects
+                       = XM_DRAG_SIDE_EFFECT (xm_side_effect_from_action 
(FRAME_DISPLAY_INFO (f),
+                                                                          
x_dnd_wanted_action),
+                                              XM_DROP_SITE_VALID,
+                                              xm_side_effect_from_action 
(FRAME_DISPLAY_INFO (f),
+                                                                          
x_dnd_wanted_action),
+                                              XM_DROP_ACTION_DROP_CANCEL);
+                     dmsg.x = 0;
+                     dmsg.y = 0;
+                     dmsg.index_atom = FRAME_DISPLAY_INFO 
(f)->Xatom_XdndSelection;
+                     dmsg.source_window = FRAME_X_WINDOW (f);
+
+                     x_dnd_send_xm_leave_for_drop (FRAME_DISPLAY_INFO (f), f,
+                                                   x_dnd_last_seen_window,
+                                                   hold_quit.timestamp);
+                     xm_send_drop_message (FRAME_DISPLAY_INFO (f), 
FRAME_X_WINDOW (f),
+                                           x_dnd_last_seen_window, &dmsg);
+                   }
 
-         x_set_dnd_targets (NULL, 0);
-         x_dnd_waiting_for_finish = false;
+                 x_dnd_end_window = x_dnd_last_seen_window;
+                 x_dnd_last_seen_window = None;
+                 x_dnd_last_seen_toplevel = None;
+                 x_dnd_in_progress = false;
+                 x_dnd_frame = NULL;
+               }
 
-         if (x_dnd_use_toplevels)
-           x_dnd_free_toplevels ();
+             x_set_dnd_targets (NULL, 0);
+             x_dnd_waiting_for_finish = false;
 
-         x_dnd_return_frame_object = NULL;
-         x_dnd_movement_frame = NULL;
+             if (x_dnd_use_toplevels)
+               x_dnd_free_toplevels ();
+
+             x_dnd_return_frame_object = NULL;
+             x_dnd_movement_frame = NULL;
 
-         FRAME_DISPLAY_INFO (f)->grabbed = 0;
+             FRAME_DISPLAY_INFO (f)->grabbed = 0;
 #ifdef USE_GTK
-         current_hold_quit = NULL;
+             current_hold_quit = NULL;
 #endif
-         /* Restore the old event mask.  */
-         XSelectInput (FRAME_X_DISPLAY (f),
-                       FRAME_DISPLAY_INFO (f)->root_window,
-                       root_window_attrs.your_event_mask);
+             /* Restore the old event mask.  */
+             XSelectInput (FRAME_X_DISPLAY (f),
+                           FRAME_DISPLAY_INFO (f)->root_window,
+                           root_window_attrs.your_event_mask);
 #ifdef HAVE_XKB
-         if (FRAME_DISPLAY_INFO (f)->supports_xkb)
-           XkbSelectEvents (FRAME_X_DISPLAY (f), XkbUseCoreKbd,
-                            XkbStateNotifyMask, 0);
+             if (FRAME_DISPLAY_INFO (f)->supports_xkb)
+               XkbSelectEvents (FRAME_X_DISPLAY (f), XkbUseCoreKbd,
+                                XkbStateNotifyMask, 0);
 #endif
-         /* Delete the Motif drag initiator info if it was set up.  */
-         if (x_dnd_motif_setup_p)
-           XDeleteProperty (FRAME_X_DISPLAY (f), FRAME_X_WINDOW (f),
-                            FRAME_DISPLAY_INFO (f)->Xatom_XdndSelection);
-         quit ();
+             /* Delete the Motif drag initiator info if it was set up.  */
+             if (x_dnd_motif_setup_p)
+               XDeleteProperty (FRAME_X_DISPLAY (f), FRAME_X_WINDOW (f),
+                                FRAME_DISPLAY_INFO (f)->Xatom_XdndSelection);
+             quit ();
+           }
+#ifndef USE_GTK
+       }
+      else
+       {
+         if (x_dnd_movement_frame)
+           x_dnd_movement_frame = NULL;
+
+         if (hold_quit.kind != NO_EVENT)
+           EVENT_INIT (hold_quit);
        }
+#endif
     }
 
   x_set_dnd_targets (NULL, 0);