refactor: popups for nav bar / segmented buttons

src/widget/menu.rs

@@ -72,6 +72,7 @@ mod menu_inner;
 mod menu_tree;
 pub use menu_tree::{
     MenuItem as Item, MenuTree as Tree, menu_button, menu_items as items, menu_root as root,
+    nav_context,
 };
 
 pub use crate::style::menu_bar::{Appearance, StyleSheet};