anchor.diff:    CanvasElement canvas;
     final List<RectangleTransform> letterTiles = new List<RectangleTransform>();
     final Set<int> selectedTiles = new Set<int>();
  +  String selectedLetters = '';
   
     // Reference to the main game object.
     final Game game;
  
positive.code:           var transform = getTileRectangle(i, j);
            for (var position in touch.positions) {
              if (transform.contains(position.x, position.y)) {
                selectedTiles.add(tileIndex(i, j));
              }
            }
          }
        }
      } else {
        selectedTiles.clear();
      }
      if (selectedTiles.length > 0) {
        print(selectedTiles);
      }
    }
  
  
negative.code: 
      const int X_OFFSET = 5;
      const int Y_OFFSET = 60;
  
      for (int i = 0; i < letterTiles.length; i++) {
        int x = letterTiles[i].left;
        int y = letterTiles[i].top;
  