Returns #t if the position-specified item is selected, #f otherwise.
Returns #t if the nth item is selected. List box choices are numbered from 0.
![[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}