anchor.diff:  
           // position the square
           final etx = se.addTransform();
  -        etx.setToTranslation(coords.Item1 * SquareElement._size, coords.Item2 * SquareElement._size);
  +        etx.setToTranslation(
  +            _edgeOffset + coords.Item1 * SquareElement._size,
  +            _edgeOffset + coords.Item2 * SquareElement._size);
   
           _elements[i] = se;
         }
  
positive.code: class GameElement extends ElementParentImpl {
    final bool _targetMode;
    final dartlib.EventHandle _targetChanged;
  
  
negative.code: 
    void drawOverride(CanvasRenderingContext2D ctx) {
      _updateElements();
  
      _drawBackground(ctx);
  
      // draw children via super
      super.drawOverride(ctx);
  
      // draw target element
      _drawTarget(ctx);
    }
  
    // TODO: draw this on another layer? Cache?
    void _drawBackground(CanvasRenderingContext2D ctx) {
      final rightBgLoc = SquareElement._size * (_game.field.width -1) + _edgeOffset;
      final bottomBgLoc = SquareElement._size * (_game.field.height -1) + _edgeOffset;
  
      drawTextureKeyAt(ctx, 'game_board_corner_top_left.png');
  
      drawTextureKeyAt(ctx, 'game_board_corner_top_right.png',
          new dartlib.Coordinate(rightBgLoc, 0));
  
      drawTextureKeyAt(ctx, 'game_board_corner_bottom_left.png',
                       new dartlib.Coordinate(0, bottomBgLoc));
      drawTextureKeyAt(ctx, 'game_board_corner_bottom_right.png',
          new dartlib.Coordinate(rightBgLoc, bottomBgLoc));
  
      for(var i = 1; i < _game.field.width - 1; i++) {
        final xLoc = SquareElement._size * i + _edgeOffset;
        drawTextureKeyAt(ctx, 'game_board_side_top.png',
            new dartlib.Coordinate(xLoc, 0));
        drawTextureKeyAt(ctx, 'game_board_side_bottom.png',
            new dartlib.Coordinate(xLoc, bottomBgLoc));
      }
  
      for(var i = 1; i < _game.field.height - 1; i++) {
        final yLoc = SquareElement._size * i + _edgeOffset;
        drawTextureKeyAt(ctx, 'game_board_side_left.png',
            new dartlib.Coordinate(0, yLoc));
        drawTextureKeyAt(ctx, 'game_board_side_right.png',
            new dartlib.Coordinate(rightBgLoc, yLoc));
      }
    }
  
    void _drawTarget(CanvasRenderingContext2D ctx) {
  