title: How to set minimum height of SliverAppBar within NestedScrollView in Flutter
body: <p>I'd like to use SliverAppBar within NestedScrollView in an ordinary Scaffold app. I also would like to have some minimum height of the app bar when user scrolls down. </p>
  
  <p>I can't figure out how to use either PreferredSize widget nor any other solution found online e.g. <a href="https://stackoverflow.com/questions/52933076/minimum-height-in-sliverappbar-flutter">this</a>.</p>
  
  <p>Here is my current simplified solution:</p>
  
  <pre class="lang-dart prettyprint-override"><code>import 'package:flutter/material.dart';
  
  void main() =&gt; runApp(MyApp());
  
  class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(primarySwatch: Colors.blue, fontFamily: 'Oswald'),
        home: SliverHome(),
      );
    }
  }
  
  class SliverHome extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return Container(
        child: testHome(),
      );
    }
  
    Widget testHome() {
      return Scaffold(
        body: NestedScrollView(
          headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
            return &lt;Widget&gt;[
              SliverAppBar( // this is where I would like to set some minimum constraint
                expandedHeight: 300,
                floating: false,
                pinned: true,
                flexibleSpace: Container(
                  padding: EdgeInsets.all(10),
                  height: 340,
                  width: double.infinity,
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.end,
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: &lt;Widget&gt;[
                      Container(
                        height: 40,
                      ),
                      Container(
                        height: 60,
                      ),
                      Expanded(child: Container()),
                      Text('TEST'),
                    ],
                  ),
                  decoration: BoxDecoration(
                      image: DecorationImage(
                          image: NetworkImage('https://picsum.photos/400/400'),
                          fit: BoxFit.cover)),
                ),
              )
            ];
          },
          body: Container(),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () =&gt; {},
          tooltip: '+',
          child: Icon(Icons.accessibility_new),
        ),
      );
    }
  }
  </code></pre>
  
  <p>I'd like to stop shrinking of the app bar somewhere near 60 dp </p>
  
  <p><img src="https://i.imgur.com/yVXxsXv.png" alt="screenshot"></p>