anchor.diff:  
       Panel = wxPanel:new(Frame, []),
       Bitmap = wxBitmap:new(16 * Cols, 16 * Rows),
  +    Board = create_and_draw_board(Config, Bitmap),
   
       wxPanel:connect(Panel, left_up, [{userData, dummy}]),
       wxPanel:connect(Panel, middle_up, [{userData, dummy}]),
       wxPanel:connect(Panel, right_up, [{userData, dummy}]),
       wxPanel:connect(Panel, paint, [callback]),
       wxPanel:connect(Panel, key_up),
  -
  -    Board = board:new(Rows, Cols, Mines),
  -    [draw_icon(Bitmap, covered, {Px, Py}) || Px <- lists:seq(0, Rows-1),
  -                                             Py <- lists:seq(0, Cols-1)],
   
       wxFrame:centerOnScreen(Frame),
       wxFrame:show(Frame),
  
positive.code: -behaviour(wx_object).
  
  %% Client API
  -export([ start_link/3
          , stop/1
          ]).
  
  
negative.code:               {wxBitmap:getWidth(Bitmap), wxBitmap:getHeight(Bitmap)},
                MemoryDC, {0,0}),
      wxMemoryDC:destroy(MemoryDC).
  
  refresh(#state{mode=screensaver, bitmap=Bitmap}) ->
      DC = wxScreenDC:new(),
      redraw(DC, Bitmap),
      wxScreenDC:destroy(DC);
  refresh(#state{mode=interactive, frame=Frame}) ->
      wxPanel:refresh(Frame).
  