vScroll                                        (Assignable)

        Contains an optional ScrollBar object whose orientation must be
        vertical.  The scroll bar thumb position reflects the relationship
        between the current first visible item on the screen and the total
        number of possible top items (total number of items - number of
        visible items - 1).

        When present, the scroll bar is automatically integrated within the
        behaviors of the following ListBox object methods:  addItem(),
        display(), delItem(), hitTest(), insItem(), nextItem(), prevItem(),
        and select().