anchor.diff:  class SquareElement extends PElement {
     static const int _size = 80;
     static const String _textureName = "balloon.png";
  +  static const String _flagName = 'balloon_tagged_!.png';
     static const List<String> _numberMap = const["game_board_center",
                                                  "number_one", "number_two",
                                                  "number_three", "number_four",
  
positive.code:     switch(_squareState) {
        case SquareState.hidden:
          drawTextureKeyAt(ctx, _textureName);
          break;
        case SquareState.revealed:
          final adjCount = _adjacentCount;
  
negative.code: 
    Dynamic get _fillStyle {
      switch(_squareState) {
        case SquareState.mine:
          return 'red';
        case SquareState.safe:
  