anchor.diff:          double drawStart = scrollOffset + alignmentDelta;
           itemNumber = math.max(0, (drawStart / _itemHeight).floor());
   
  -        transformStyle =
  -            'transform: translateY(${(alignmentDelta).toStringAsFixed(2)}px)';
  +        transform.translate(0.0, alignmentDelta);
         }
       }
   
  -    return new Container(
  -      style: _style,
  +    // TODO(abarth): Add a clip.
  +    return new BlockContainer(
         children: [
  -        new Container(
  -          style: _scrollAreaStyle,
  -          inlineStyle: transformStyle,
  -          children: buildItems(itemNumber, drawCount)
  +        new Transform(
  +          transform: transform,
  +          child: new BlockContainer(children: buildItems(itemNumber, drawCount))
           )
         ]
       );
  
positive.code: // found in the LICENSE file.
  
  import '../animation/scroll_behavior.dart';
  import '../debug/tracing.dart';
  import '../fn2.dart';
  import 'dart:math' as math;
  import 'dart:async';
  import 'scrollable.dart';
  
  abstract class FixedHeightScrollable extends Scrollable {
    static final Style _style = new Style('''
      overflow: hidden;
      position: relative;
      will-change: transform;'''
    );
  
    static final Style _scrollAreaStyle = new Style('''
      position:relative;
      will-change: transform;'''
    );
  
    FixedHeightScrollable({
      Object key
    }) : super(key: key);
  
    ScrollBehavior createScrollBehavior() => new OverscrollBehavior();
    OverscrollBehavior get scrollBehavior => super.scrollBehavior as OverscrollBehavior;
  
negative.code:   }
  
    void _measureHeights() {
      if (_itemHeight != null)
        return;
      setState(() {
        // TODO(abarth): Actually measure these heights.
        _height = 500.0; // root.height;
        assert(_height > 0);
        _itemHeight = 100.0; // item.height;
        assert(_itemHeight > 0);
        scrollBehavior.containerHeight = _height;
        scrollBehavior.contentsHeight = _itemHeight * _itemCount;
      });
    }
  
  