Build menu trees.
Menus are a way to arrange many actions in groups of more manageable size.
A menu can be seen as a
MenuTree. It has a list of children:
- Leaf nodes are made of a label and a callback
- Sub-trees are made of a label, and another
- Delimiters are just there to separate groups of related children.
The menubar is the main way to show menus.
Root of a menu tree.
Node in the menu tree.