Window结构体有一个 方法，它允许更新菜单项：menu_handle

fn main() {
  let menu = Menu::new(); // configure the menu
  tauri::Builder::default()
    .menu(menu)
    .setup(|app| {
      let main_window = app.get_window("main").unwrap();
      let menu_handle = main_window.menu_handle();
      std::thread::spawn(move || {
        // you can also `set_selected`, `set_enabled` and `set_native_image` (macOS only).
        menu_handle.get_item("item_id").set_title("New title");
      });
      Ok(())
    })
}