anchor.diff:  
     Widget build(BuildContext context) {
       return new Scaffold(
  -      toolBar: new ToolBar(
  -        center: new Text('Usage Example')
  +      appBar: new AppBar(
  +        title: new Text('Usage Example')
         ),
         body: new Column(
           children: <Widget>[
  
positive.code:   runApp(new MaterialApp(
      title: 'Usage Example',
      theme: new ThemeData.dark(),
      routes: <String, RouteBuilder>{
        '/': (RouteArguments args) => new FlutterDemo(ga)
      }
    ));
  }
  
  class FlutterDemo extends StatefulComponent {
    FlutterDemo(this.ga);
    Analytics ga;
    State createState() => new _FlutterDemoState();
  
negative.code:           ),
            new ListItem(
              onTap: () => _handleOptIn(!config.ga.optIn),
              leading: new Checkbox(
                value: config.ga.optIn,
                onChanged: _handleOptIn
              ),
              title: new Text("Opt in to analytics")
            )
          ],
          mainAxisAlignment: MainAxisAlignment.spaceAround
        ),
        floatingActionButton: new FloatingActionButton(
          child: new Icon(icon: Icons.add),
  