title: Flutter how to bring front widget
body: <p>is there anyway that we can bring the widget front of the screen and let other widget behind the screen?, tried <code>Stack</code> widget but not working, I'm implementing a Google Maps using flutter <code>google_maps_flutter</code> library, see code below:</p>
  
  <pre><code>import 'dart:ui' as ui;
  import 'package:google_maps_flutter/google_maps_flutter.dart';
  import 'package:flutter/material.dart';
  
  final size = MediaQueryData.fromWindow(ui.window).size;
  final GoogleMapOverlayController controller =
      GoogleMapOverlayController.fromSize(
    width: size.width,
    height: size.height,
  );
  
  class GoogleMapView extends StatefulWidget {
    _GoogleMapViewState createState() =&gt; _GoogleMapViewState();
  }
  
  class _GoogleMapViewState extends State&lt;GoogleMapView&gt; {
    final mapController = controller.mapController;
    final Widget mapWidget = GoogleMapOverlay(controller: controller);
  
    @override
    void initState() {
      super.initState();
      GoogleMapController.init();
    }
  
    @override
    Widget build(BuildContext context) {
      return new MaterialApp(
        home: new Container(
          alignment: Alignment.center,
          height: size.height,
          width: size.width,
          child: new Stack(
            children: &lt;Widget&gt;[
              mapWidget,
              new Container(
                height: 100.0,
                alignment: Alignment.topCenter,
                child: new Text('Hey there!'),
              )
            ],
          ),
        ),
        navigatorObservers: &lt;NavigatorObserver&gt;[controller.overlayController],
      );
    }
  }
  </code></pre>
  
  <p>See the <a href="https://i.stack.imgur.com/GvwWO.png" rel="nofollow noreferrer">screenshot</a> which it should have a red color on top of the google map aligned in the top corner of the screen.  How to implement this using flutter <code>Stack</code> widget, I'm having problem with this since yesterday and couldn't find any solution, can anyone help me with this? thanks!</p>