diff --git a/panda/src/testbed/gui_demo.cxx b/panda/src/testbed/gui_demo.cxx
index 0ffbc64b13..aa8d221edf 100644
--- a/panda/src/testbed/gui_demo.cxx
+++ b/panda/src/testbed/gui_demo.cxx
@@ -750,6 +750,8 @@ static void test13(GuiManager* mgr, Node* font) {
   lb1->add_item(s4);
   lb1->add_item(s5);
   lb1->thaw();
+  ub->manage(mgr, event_handler);
+  db->manage(mgr, event_handler);
   lb1->manage(mgr, event_handler);
   lb1->start_behavior();
 }