GraphWindow              Sets Graphics Window for Clipping Purposes

GraphWindow(X1,Y1,X2,Y2 : Integer);     [TP]

    Defines a graphics window with (X1,Y1) as the upper-left corner and
    (X2,Y2) as the lower-right corner. Any pixels drawn outside this
    window are ignored.

           X1,Y1    Screen coordinates (column, row); upper-left corner of
                    graphics window in pixels.

           X2,Y2    Screen coordinates (column, row); lower-right corner
                    of graphics window in pixels.

          Notes:    The default graphics window is (0,0),(319, 199) for
                    320 x 200 graphics modes and (0,0),(639,199) for 640 x
                    200 graphics modes. Notice that this is the entire
                    screen.

                    Setting the mode using GraphMode, GraphColorMode, or
                    HiRes also changes the graphics window to the entire
                    screen. Hence be careful to change the GraphWindow
                    AFTER the graphics mode has been set.

  -------------------------------- Example ---------------------------------

           GraphMode;                  { Currently entire screen is window }
           GraphWindow(80,0,160,30);   { Define graphics window }
           Draw(0,25,319,25,1);        { only portion in window shows }