Procedure VertSlideIcon(Active:Boolean)

    Active = True

    This adds the slide  bar  and  its  buttons  to  the  window's linked
    list of buttons.  The slide bar is not displayed or updated.

    Only the vertical slide bar is  added  to the list, use HorzSlideIcon
    to add the horizontal slide bar to the list.

    Active = False

    This removes the slide bar buttons from the list.