1 files changed, 4 insertions, 0 deletions
diff --git a/dnd.py b/dnd.py
index 996a961..9f94a02 100644
--- a/dnd.py
+++ b/dnd.py
@@ -77,6 +77,10 @@ class DragDropHooks:
         return False
 
     def onCopyOrDrag(self, event, trans):
+        if not event:
+            logging.warning('DragDropHooks.onCopyOrDrag: no event received.')
+            return True
+
         mouse_event = event.queryInterface(interfaces.nsIDOMMouseEvent)
         event_target = mouse_event.target
         target_node = event_target.queryInterface(interfaces.nsIDOMNode)