Procedure Open(NX1,NY1,NX2,NY2:Word;Forg,Back,ShadForg,ShadBack:Byte;
                   LStyle:LineStyles;SStyle:ShadowStyles)

    This opens a  window  from  NX1,NY1  (top  left)  to  NX2,NY2 (bottom
    right) using  foreground  colour  Forg  and  background  colour Back.
    The shadow (if SStyle is  not  NoShade)  will  have foreground colour
    ShadForg and background  colour  ShadBack.   Note  that for the solid
    shadow, only one colour is used.  The  window is surrounded in either
    no line, a single line or a double line, determined by LStyle.

    This should be the first procedure  you call for the window.  It must
    never be called again until a Close is called.

    The window initializes its own personal buttons (to NIL).

    It is up to the  programmer  to  ensure  there  is  sufficient memory
    available for the procedure to save the background.