The IMenuItemRenderer interface defines the interface
that a menu item renderer for a Menu control must implement.
The menu item renderers are often recycled. Once they are created,
they may be used again simply by being given new data.
Therefore, in individual implementations, component developers must
make sure that component properties are not assumed to contain
specific initial, or default values.
To implement this interface, a component developer must define a
setter and getter method that implements the menu property.
Typically, the setter method writes the value of the data property
to an internal variable, and the getter method returns the current
value of the internal variable, as the following example shows:
// Internal variable for the property value.
private var _menu:Menu;
// Define the getter method.
public function get menu():Menu
// Define the setter method.
public function set menu(value:Menu):void
_menu = value;