Avoid MoveEvent action in Drag&Drop

Close #2672
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/qt4/main_interface.cpp

@@ -1095,6 +1095,10 @@ void MainInterface::dropEvent(QDropEvent *event)
 
 void MainInterface::dropEventPlay( QDropEvent *event, bool b_play )
 {
+     event->setDropAction( Qt::CopyAction );
+     if( !event->possibleActions() & Qt::CopyAction )
+         return;
+
      const QMimeData *mimeData = event->mimeData();
 
      /* D&D of a subtitles file, add it on the fly */
@@ -1107,7 +1111,7 @@ void MainInterface::dropEventPlay( QDropEvent *event, bool b_play )
                                          mimeData->urls()[0].toLocalFile() ) ),
                                     true ) )
             {
-                event->acceptProposedAction();
+                event->accept();
                 return;
             }
         }
@@ -1125,7 +1129,7 @@ void MainInterface::dropEventPlay( QDropEvent *event, bool b_play )
             RecentsMRL::getInstance( p_intf )->addRecent( s );
         }
      }
-     event->acceptProposedAction();
+     event->accept();
 }
 void MainInterface::dragEnterEvent(QDragEnterEvent *event)
 {