title: Multiple SliverAppBar in a CustomScrollView
body: <p>I require to have multiple SliverAppBar, each with its own SliverList in a single view.  Currently only the first SliverAppBar is responding correctly.</p>
  
  <p>I have of course, done extended searching on SO and Google, but have not found a solution yet!</p>
  
  <pre><code>  @override
    Widget build(BuildContext context) {
       return Scaffold(
          appBar: AppBar(
            title: Text('Details'),
          ),
          body: CustomScrollView(
            slivers: &lt;Widget&gt;[
              new SliverAppBar(
                floating: true,
                automaticallyImplyLeading: false,
                title: Text('1'),
              ),
              new SliverList(
                delegate: SliverChildBuilderDelegate(
                  (context, index) =&gt; ListTile(title: Text('Text 1')),
                  childCount: 20,
                ),
              ),
              new SliverAppBar(
                automaticallyImplyLeading: false,
                title: Text('2'),
                floating: true,
              ),
              new SliverList(
                delegate: SliverChildBuilderDelegate(
                  (context, index) =&gt; ListTile(title: Text('Text 2')),
                  childCount: 20,
                ),
              ),
            ],
          ),
        );
    }
  </code></pre>
  
  <p>If you do scroll, I expect to see the title "2" floating as well, when you are scrolling the list.</p>