anchor.diff:  
   create_and_draw_board({Rows, Cols, Mines}, Bitmap) ->
       Board = board:new(Rows, Cols, Mines),
  -    [draw_icon(Bitmap, covered, {Px, Py}) || Px <- lists:seq(0, Rows-1),
  -                                             Py <- lists:seq(0, Cols-1)],
  +    draw_grid(Bitmap, Rows, Cols),
       Board.
   
   newgame(#state{bitmap=Bitmap, config=Config} = State) ->
  
positive.code:     wxScreenDC:destroy(DC);
  refresh(#state{mode=interactive, frame=Frame}) ->
      wxPanel:refresh(Frame).
  
negative.code:     io:format("config: ~p~n", [Config]),
      Bitmap = wxBitmap:new(16 * Cols, 16 * Rows),
      Board = create_and_draw_board(Config, Bitmap),
      State = #state{config=Config, bitmap=Bitmap, board=Board, mode=screensaver},
      Frame = wxFrame:new(Server, ?wxID_ANY, "MinesweepErl", []),
      refresh(State),
      timer:send_interval(?MOVE_INTERVAL, move),
      {Frame, State#state{frame=Frame}};
  do_init([Server, {Rows, Cols, _Mines}=Config]) ->
      Frame = wxFrame:new(Server, ?wxID_ANY, "MinesweepErl",
                          [{style,
  