Add check to key_press_event for keyname returning None

deluge/ui/gtkui/files_tab.py

@@ -522,12 +522,11 @@ class FilesTab(Tab):
 
     def _on_key_press_event(self, widget, event):
         keyname = gtk.gdk.keyval_name(event.keyval)
+        if keyname is not None:
             func = getattr(self, 'keypress_' + keyname, None)
             selected_rows = self.listview.get_selection().get_selected_rows()[1]
             if func and selected_rows:
                 return func(event)
-        else:
-            return
 
     def keypress_Menu(self, event):
         self.file_menu.popup(None, None, None, 3, event.time)