<oPopUp>:getNext() --> nPosition

        Returns a numeric value that indicates the position within the pop-up
        menu of the next selectable item.  getNext() returns 0 in the event
        that the current item is the last selectable item or the pop-up menu
        does not contain a selectable item.

        getNext() is a method of the PopUpMenu class that is used for
        determining the position of the next selectable item in a pop-up
        menu.  getNext() searches for the next selectable item starting at
        the item immediately after the current item.  The term selectable is
        defined as a menu item that is enabled and whose caption, is not a
        menu separator.

        Note:  getNext() does not change the currently selected menu
        item.  In order to change the currently selected pop-up menu item,
        you must call the PopUpMenu:select() method.