glutAddMenuEntry( "Sub menu B3 (06)", 16 );
glutAddSubMenu( "Going to sub menu A", subMenuA );
glutMenuDestroyFunc ( MenuDestroy ); /* callback specific to this menu */
glutAddMenuEntry( "Sub menu B3 (06)", 16 );
glutAddSubMenu( "Going to sub menu A", subMenuA );
glutMenuDestroyFunc ( MenuDestroy ); /* callback specific to this menu */