Add scoped overlay hosts

examples/message_list.rs

@@ -79,7 +79,7 @@ impl DefaultAppState for State {
             .masked()
             .background(rect(PaintId::WHITE))
             .add_strong(rsc);
-        ui_state.set_root(root.any());
+        ui_state.set_root(rsc, root.any());
 
         Self { ui_state }
     }