#define BOARD_MAX    18
#define BOARD_SIZE   19

% set colors
/board_color   0 0 0 rgbcolor def          % black
/line_color    1 1 1 rgbcolor def            % white

/draw_board { % - => - (draw the playing surface)
    board_color setcolor 
    clippath fill
    line_color setcolor
    0 1 BOARD_MAX {
        dup 0 moveto 0 BOARD_MAX rlineto
        0 exch moveto BOARD_MAX 0 rlineto
    } for
    stroke
    pause
} def

/makewin { %  - => - (builds a test window)
      /GoWindow DefaultWindow                        % create a subclass
      dictbegin
           /FrameLabel ( 1st Go board ) def
      dictend
      classbegin
           /PaintClient { draw_board } def
           /PaintIcon { draw_board } def  
           /ClientPath { % x y w h => -
                4 2 roll translate
                BOARD_SIZE div exch BOARD_SIZE div exch scale
            .   5 .5 translate
                -.5 -.5 BOARD_SIZE BOARD_SIZE rectpath
        } def
        /IconPath {ClientPath} def
       classend def

       /win framebuffer /new GoWindow send def          % cliche
       /reshapefromuser win send                        % resize window
       /map win send                                        % draw it
} def

makewin