set-first-visible-item in list-box%

Scrolls the list box so that the specified item is at the top of the list box display.

A list box's scroll position can be changed by the user clicking the control, and such changes do not go through this method. A program cannot detect when the scroll position changes except by polling get-first-visible-item.

• (send a-list-box set-first-visible-item n) -> void
     n : exact non-negative integer

  Shows the item indexed by n at the list box's top. List box items are indexed from 0. If n is equal to or larger than the number of choices, an exn:fail:contract exception is raised.