Permanent view with navigation bar in Flutter

You can use the same approach here. Parent widget can have two parts: Navigator and PermanentView. By pushing routes you will change only Navigator widget. Demo:

import 'package:flutter/material.dart';class MyApp extends StatefulWidget {  @override  _MyAppState createState() => new _MyAppState();}class _MyAppState extends State<MyApp> {  Route _onRoute(RouteSettings settings) {    final str = settings.name.split("/")[1];    final index = int.parse(str, onError: (s) => 0);    return new MaterialPageRoute(        builder: (BuildContext context) => new Home(index: index));  }  @override  Widget build(BuildContext context) {    return new Column(      children: <Widget>[        new Expanded(          child: new MaterialApp(            title: 'Flutter Demo',            onGenerateRoute: _onRoute,          ),        ),        new Container(          height: 44.0,          color: Colors.blueAccent,          child: new Center(            child: new Text("permanent view"),          ),        )      ],    );  }}class Home extends StatelessWidget {  Home({Key key, this.index}) : super(key: key);  final int index;  @override  Widget build(BuildContext context) => new Scaffold(        appBar: new AppBar(          title: new Text("View ${index}"),        ),        body: new Center(          child: new Column(            mainAxisSize: MainAxisSize.min,            children: <Widget>[              new Text("View ${index}"),              new FlatButton(                  onPressed: () =>                      Navigator.of(context).pushNamed("/${index + 1}"),                  child: new Text("Push"))            ],          ),        ),      );}void main() {  runApp(    new MyApp(),  );}