Window procedure

  DECLARATION:  Window(X1, Y1, X2, Y2 : Byte);

      PURPOSE:  Defines a text window on the screen.

         UNIT:  CRT

      REMARKS:  X1 and Y1 are the coordinates of the upper left
                hand corner of the window, and X2 and Y2 are the lower
                right hand corner.  The minimum size for the text window is
                1 column by 1 row.

                WindMin and WindMax store the current window
                definition.  A Call to Window always moves the
                cursor to (1,1).