Procedure VertSlideBar(CurPos,MaxPos:LongInt;Patrn,PatClr:Word)

    A window may have a  slide  bar.    On  the  slide bar is a slide bar
    button and an up arrow and a down arrow.

    (Horizontal slide  bars  are  similar  except  they  lie horizontally
    and have a left and right arrow.)

    This is usually used for text in a  window.  The user can either drag
    the button up and down (say to  scroll  the text), or click on the up
    arrow (to move up 1 line) or the down arrow (to move down 1 line).

    The user may also click anywhere on the bar to move the button there.
    There is a similar system in the Turbo Pascal 6 IDE.

    The slide bar on a window is used as follows:

    There is a current position  and  a  maximum  position.   The current
    position is  a  value  from  0  to  MaxPos.   That  is,  when  CurPos
    is 0, the button is at  the  top  (horizontal  left)  and  when it is
    MaxPos it is at the bottom (horizontal right).

    Patrn and  PatClr  specify  the  pattern  and  pattern  colour of the
    slide bar.