Update menu_bar.rs

src/widget/menu/menu_bar.rs

@@ -211,6 +211,7 @@ where
         self.height
     }
 
+    #[allow(invalid_reference_casting)]
     fn diff(&mut self, tree: &mut Tree) {
         if tree.children.len() > self.menu_roots.len() {
             tree.children.truncate(self.menu_roots.len());