master 55e9d729ca: Fix Motif DND after atom ownership is lost due to frame destruction

[Po Lu]

branch: master
commit 55e9d729ca34c4dd05bfb0d606425b8fc27d53ca
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix Motif DND after atom ownership is lost due to frame destruction
    
    * src/xterm.c (xm_get_drag_atom_1): Record owner.
    (x_free_frame_resources): Clear drag atom if owner was freed.
    * src/xterm.h (struct x_display_info): New field
    `motif_drag_atom_owner'.
---
 src/xterm.c | 7 +++++++
 src/xterm.h | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/src/xterm.c b/src/xterm.c
index cc47427a9d..04e3223478 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -2281,6 +2281,7 @@ xm_get_drag_atom_1 (struct x_display_info *dpyinfo,
     }
 
   dpyinfo->motif_drag_atom_time = dpyinfo->last_user_time;
+  dpyinfo->motif_drag_atom_owner = source_frame;
 
   XUngrabServer (dpyinfo->display);
   return atom;
@@ -25310,6 +25311,12 @@ x_free_frame_resources (struct frame *f)
     g_object_unref (FRAME_OUTPUT_DATA (f)->scrollbar_foreground_css_provider);
 #endif
 
+  if (f == dpyinfo->motif_drag_atom_owner)
+    {
+      dpyinfo->motif_drag_atom_owner = NULL;
+      dpyinfo->motif_drag_atom = None;
+    }
+
   if (f == dpyinfo->x_focus_frame)
     dpyinfo->x_focus_frame = 0;
   if (f == dpyinfo->x_focus_event_frame)
diff --git a/src/xterm.h b/src/xterm.h
index 119382c73c..ad0df6bff9 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -576,6 +576,9 @@ struct x_display_info
   /* When it was owned.  */
   Time motif_drag_atom_time;
 
+  /* The frame that currently owns `motif_drag_atom'.  */
+  struct frame *motif_drag_atom_owner;
+
   /* Extended window manager hints, Atoms supported by the window manager and
      atoms for setting the window type.  */
   Atom Xatom_net_supported, Xatom_net_supporting_wm_check;