The application does not have to worry about handling the menu display.
The menus are simply submitted to Intuition and the application waits for
Intuition to send messages about the selection of menu items.  These
messages, along with the data in the menu structures, give the application
all the information required for the processing of the user actions.

Menus can be set up with the GadTools library on systems running Release 2
or a later version of the OS.  Since GadTools makes menu set up easier and
handles much of the detail work of menu processing (including adjusting to
the current font selection), it should be used whenever possible.

Under 1.3 (V34) and older versions of the OS, GadTools is not available.
To set up menus that work with these older systems, you use the menu and
menuitem structures.  in general, for each menu in the menu bar, you
declare one instance of the Menu structure.  For each item or sub-item
within a menu, you declare one instance of the MenuItem structure.
Text-based menus like the kind used in this chapter require an additional
intuitext structure for each menu, menu item and sub-item.  all these
structures are defined in <intuition/intuition.h>.

The data structures used for menus are linked together to form a list
known as a menu strip.  For all the details of how the structures are
linked and for listings of menu and menuitem, see the menu data structures"
section later in this chapter.

 submitting and removing menu strips 
 simple menu example 
 disabling menu operations 
 changing menu strips 
 sharing menu strips 
 menu selection messages 
 menu numbers 
 help key processing in menus 
 menu layout 
 about menu item boxes 
 attribute items and the checkmark 
 toggle selection 
 mutual exclusion 
 managing the state of checkmarks 
 command key sequences 
 enabling and disabling menus and menu items 
 intercepting normal menu operations