Do not automatically save file immediately after loading with ctrl-o

Fix accidental switch fallthrough.

widgets/coreWidget/keyHandling.cc

@@ -605,6 +605,7 @@ void CoreWidget::coreKeyPressEvent  (QKeyEvent* _e){
 
       case Qt::Key_O :
         loadMenu();
+        return;
 
       case Qt::Key_S :
         saveMenu();