anchor.diff:          )
         ),
         appBarBehavior: AppBarBehavior.under,
  +      // The block's padding just exists to occupy the space behind the flexible app bar.
  +      // As the block's padded region is scrolled upwards, the app bar's height will
  +      // shrink keep it above the block content's and over the padded region.
         body: new Block(
          scrollableKey: _scrollableKey,
  +       padding: new EdgeInsets.only(top: _kFlexibleSpaceMaxHeight + statusBarHeight),
          children: _listItems
         )
       );
  
positive.code: 
    @override
    Widget build(BuildContext context) {
      return new Scaffold(
        key: _homeKey,
        scrollableKey: _scrollableKey,
  
negative.code:   void initState() {
      super.initState();
  
      final ThemeData themeData = Theme.of(context);
      final TextStyle headerStyle = themeData.textTheme.body2.copyWith(color: themeData.accentColor);
      String category;
  