This method is called when the default action of the item is taken.
This defaultly calls the list-box callback item with
![[previous]](../icons/left.gif){kind=icon}
![[up]](../icons/up.gif){kind=icon}
![[next]](../icons/right.gif){kind=icon}
![[contents]](../icons/contents.gif){kind=icon}
![[index]](../icons/index.gif){kind=icon}