better global state structure?

core/src/widget/like.rs

@@ -19,7 +19,7 @@ pub trait WidgetLike<State: 'static + HasUi, Tag>: Sized {
     }
 
     fn set_root(self, state: &mut State) {
-        state.ui().root = Some(self.add(state));
+        state.get_mut().root = Some(self.add(state));
     }
 
     fn handles(self, state: &mut State) -> WidgetHandles<Self::Widget> {