anchor.diff:  class SquareElement extends PElement {
     static const int _size = 80;
     static const String _textureName = "balloon.png";
  +  static const List<String> _numberMap = const["game_board_center",
  +                                               "number_one", "number_two",
  +                                               "number_three", "number_four",
  +                                               "number_five", "number_six",
  +                                               "number_seven", "number_eight"];
  +
     final int x, y;
   
     SquareElement(this.x, this.y) : super(_size, _size) {
  
positive.code:     switch(_squareState) {
        case SquareState.flagged:
          return 'orange';
        case SquareState.revealed:
          return 'white';
        case SquareState.mine:
          return 'red';
        case SquareState.safe:
          return 'green';
        case SquareState.hidden:
          return '#6666CC';
        default:
          throw 'not supported';
      }
    }
  }
  
negative.code:       ctx.strokeRect(0.5, 0.5, width, height, 1);
      }
  
  
  
    }
  
  