<oTopBar>:getLast() --> nPosition

        Returns a numeric value that indicates the position within the top
        bar menu of the last selectable item.  getLast() returns 0 in the
        event that the top bar menu does not contain a selectable item.

        getLast() is a method of the TopBarMenu class that is used for
        determining the position of the last selectable item in a top bar
        menu.  The term selectable is defined as a menu item that is enabled
        and whose caption, is not a menu separator.

        Note:  getLast() does not change the currently selected menu item.
        In order to change the currently selected top bar menu item, you must
        call the TopBarMenu:select() method.