GRAPHWINDOW            Define Active Graphics Window                 pp 169

 Syntax:  GraphWindow (X1,Y1,X2,Y2) ;

 Type:    Integer

 Form:    Graphics Procedure

 Purpose: Define active graphics display window for any graphics mode.

 Notes:   X1,Y1 are the absolute coordinates of the upper left corner.
          X2,Y2 are the absolute coordinates of the lower right corner.
          Defaults:  320x200 = 0,0,319,199   and   640x200 = 0,0,639,199

          Any graphics plotted outside the window will be clipped and not
          displayed.

          All coordinates are relative to the window, not the actual screen.


 Usage:
       BEGIN
          GraphColorMode               ;   { Set 320x200 color graphics mode }
          GraphWindow (50,100,200,180) ;   { Set new window coordinates      }
          GotoXY (0,0)                 ;   { Locate at 50,100 absolute       }
       END.