Function render_menu 

pub fn render_menu<'a, Message, MenuId, MenuItemId, F>(
    menu: Menu<MenuId, MenuItemId>,
    on_action: &'a F,
    is_active: bool,
) -> Element<'a, Message>
where
    Message: Clone + 'a,
    MenuId: Clone + Debug + PartialEq + 'a,
    MenuItemId: Clone + Debug + 'a,
    F: Fn(MenuAction<MenuId, MenuItemId>) -> Message + 'a,

Render a single menu (header button + dropdown when active).

on_action is called for every interaction and must map the resulting MenuAction into the application’s message type. A plain function item works well here because it has a zero-sized 'static type and can be passed by reference.