Add menu code, adapted from iced_aw

src/widget/menu.rs

@@ -0,0 +1,67 @@
+// From iced_aw, license MIT
+
+//! A [`MenuBar`] widget for displaying [`MenuTree`]s
+//!
+//! *This API requires the following crate features to be activated: `menu`*
+//!
+//! # Example
+//!
+//! ```ignore
+//! use iced::widget::button;
+//! use iced_aw::menu::{MenuTree, MenuBar};
+//!
+//! let sub_2 = MenuTree::with_children(
+//!     button("Sub Menu 2"),
+//!     vec![
+//!         MenuTree::new(button("item_1")),
+//!         MenuTree::new(button("item_2")),
+//!         MenuTree::new(button("item_3")),
+//!     ]
+//! );
+//!
+//! let sub_1 = MenuTree::with_children(
+//!     button("Sub Menu 1"),
+//!     vec![
+//!         MenuTree::new(button("item_1")),
+//!         sub_2,
+//!         MenuTree::new(button("item_2")),
+//!         MenuTree::new(button("item_3")),
+//!     ]
+//! );
+//!
+//!
+//! let root_1 = MenuTree::with_children(
+//!     button("Menu 1"),
+//!     vec![
+//!         MenuTree::new(button("item_1")),
+//!         MenuTree::new(button("item_2")),
+//!         sub_1,
+//!         MenuTree::new(button("item_3")),
+//!     ]
+//! );
+//!
+//! let root_2 = MenuTree::with_children(
+//!     button("Menu 2"),
+//!     vec![
+//!         MenuTree::new(button("item_1")),
+//!         MenuTree::new(button("item_2")),
+//!         MenuTree::new(button("item_3")),
+//!     ]
+//! );
+//!
+//! let menu_bar = MenuBar::new(vec![root_1, root_2]);
+//!
+//! ```
+//!
+
+mod flex;
+pub mod menu_bar;
+mod menu_inner;
+pub mod menu_tree;
+
+pub use crate::style::menu_bar::{Appearance, StyleSheet};
+/// A `MenuBar` collects `MenuTree`s and handles
+pub type MenuBar<'a, Message, Renderer> = menu_bar::MenuBar<'a, Message, Renderer>;
+pub use menu_inner::{CloseCondition, ItemHeight, ItemWidth, PathHighlight};
+/// Nested menu is essentially a tree of items, a menu is a collection of items
+pub type MenuTree<'a, Message, Renderer> = menu_tree::MenuTree<'a, Message, Renderer>;