Here is another example, this time from the area of graphical displays. A menu is a structure that is charged with displaying itself when the user clicks in the menu bar. A menu might be composed of menu items, which each know what to do when they are selected.
A cascading menu, sometimes called a walking menu, is a menu item that displays a new menu when it is selected. Thus, a cascading menu might be thought of as both a menu item and a menu. It would perhaps be useful to inherit behavior from both classes.