anchor.diff:    void initState() {
       super.initState();
   
  -    // The first item in the list just exists to occupy the space behind
  -    // the flexible app bar. As it's scrolled out of the way, the app bar's
  -    // height will shrink.
  -    final double statusBarHeight = (MediaQuery.of(context)?.padding ?? EdgeInsets.zero).top;
  -    _listItems.add(new SizedBox(height: _kFlexibleSpaceMaxHeight + statusBarHeight));
  -
       final ThemeData themeData = Theme.of(context);
       final TextStyle headerStyle = themeData.textTheme.body2.copyWith(color: themeData.accentColor);
       String category;
  
positive.code:         )
        ),
        appBarBehavior: AppBarBehavior.under,
        body: new Block(
         scrollableKey: _scrollableKey,
         children: _listItems
        )
      );
  
negative.code: 
    @override
    Widget build(BuildContext context) {
      final double statusBarHeight = MediaQuery.of(context).padding.top;
      return new Scaffold(
        key: _homeKey,
        scrollableKey: _scrollableKey,
  