The MENU sub-dialog
The MENU sub-dialog implements a list of choices for the user by using
action handlers.
MENU implements a list of action handlers
The following code example shows a MENU sub-dialog implementing a
                couple of action handlers with an ON ACTION clause or with a
                    COMMAND clause (action views of COMMAND can
                get the focus):
DIALOG ()
   MENU
      ON ACTION customer_view
         ...
      ON ACTION order_view
         ...
   END MENU
END DIALOG
        Control blocks in MENU
Simple
record input declared with the INPUT sub-dialog can
raise the following triggers:
In the singular MENU instruction, BEFORE MENU and AFTER
                    MENU blocks are typically used as initialization and finalization
                blocks. In an MENU sub-dialog of a DIALOG block,
                    BEFORE MENU and AFTER MENU blocks will be
                executed each time the focus goes to (BEFORE) or leaves
                    (AFTER) the action views (buttons) controlled by this
                sub-dialog.