Each submenu is actually a group of TMomentaryMenuItem instances, each representing a menu command. Each TMomentaryMenuItem has an associated MMomentaryControlState that represents the functionality of that item. When the user clicks on that menu item, the framework calls the Select function of the associated control state. The Select function then initiates the operation represented by that menu item.
NOTE See Chapter 5, "GUI Application framework concepts," in Desktop Framework Concepts for more information on control states.