The navigator takes all the available space and therefore blocks it by tapping on the red block. Is it possible to make the navigator adapt to the size of the child?

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Home(),
    );
  }
}


class Home extends StatefulWidget {
  Home({Key key}) : super(key: key);

  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  final GlobalKey<NavigatorState> _navigatorKey = new GlobalKey<NavigatorState>();
  int _count = 0;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      body: Stack(
        children: [
          Positioned.fill(
            child: GestureDetector(
              onTap: () {
                setState(() => _count++);
              },
              child: Container(
                decoration: BoxDecoration(color: Colors.red),
                child: Center(
                  child: Text('Tap anywhere to increment $_count')
                )
              )
            )
          ),
          Positioned(
            width: MediaQuery.of(context).size.width * 1,
            bottom: 0,
            child: ConstrainedBox(
              constraints: BoxConstraints(
                maxHeight: MediaQuery.of(context).size.height,
                maxWidth: MediaQuery.of(context).size.width
              ),
              child: navigator(),
            )
          )
        ],
      )
    );
  }

  navigator() {
    return Navigator(
      key: _navigatorKey,
      initialRoute: 'home/one',
      onGenerateRoute: (settings) {
        Widget view;
        switch (settings.name) {
          case 'home/one':
            view = ViewOne();
            break;
          case 'home/two':
            view = ViewTwo();
            break;
          case 'home/three':
            view = ViewThree();
            break;
          default:
        }
        var builder = (BuildContext _) {
          return view;
        };
        return MaterialPageRoute(builder: builder, settings: settings);
      },
    );
  }
}


class ViewOne extends StatelessWidget {
  const ViewOne({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return DraggableScrollableSheet(
      initialChildSize: 0.2,
      maxChildSize: 0.6,
      minChildSize: 0.2,
      builder: (context, scrollController) {
        return SingleChildScrollView(
          controller: scrollController,
          child: Container(
            decoration: BoxDecoration(color: Colors.cyan),
            height: MediaQuery.of(context).size.height * 0.6,
            width: MediaQuery.of(context).size.width,
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                Text('ViewOne', style: TextStyle(color: Colors.black, fontSize: 17)),
                RaisedButton(
                  onPressed: () => Navigator.of(context).pushNamed('home/two'),
                  child: Text('Push view two'),
                )
              ],
            ),
          )
        );
      },
    );
  }
}

class ViewTwo extends StatelessWidget {
  const ViewTwo({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ConstrainedBox(
      constraints: BoxConstraints(maxHeight: 300),
      child: SafeArea(
        child: Container(
          padding: EdgeInsets.all(20),
          height: 300,
          decoration: BoxDecoration(color: Colors.green),
          width: MediaQuery.of(context).size.width,
          child: Column(
            children: [
              Text('ViewTwo', style: TextStyle(color: Colors.black, fontSize: 17)),
              RaisedButton(
                onPressed: () => Navigator.of(context).pushNamed('home/three'),
                child: Text('Push view three'),
              ),
              RaisedButton(
                onPressed: () => Navigator.of(context).pop(),
                child: Text('Pop this view'),
              ),
              SizedBox(height: 50),
              Text('Here, ConstrainedBox and container height does not work')
            ],
          ),
        ),
      ),
    );
  }
}


class ViewThree extends StatelessWidget {
    const ViewThree({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 300,
      width: MediaQuery.of(context).size.width,
      child: Column(
        children: [
          Text('ViewThree', style: TextStyle(color: Colors.black, fontSize: 17)),
          RaisedButton(
            onPressed: () => Navigator.of(context).pop(),
            child: Text('Pop this view'),
          )
        ]
      )
    );
  }
}