<oTopBar>:select(<nPosition>) --> self

        <nPosition> indicates the position in the top bar menu of the item to
        be selected.

        select() is a method of the TopBarMenu class that is used for
        changing the selected item.  Its state is typically changed when one
        of the arrow keys is pressed or the mouse's left button is pressed
        when its cursor is within the top bar menu's screen region.