title: In Flutter how to effect parent screen state?
body: <p>Here is I wanna do. When MenuScreen's checkboxListTile selected, parent screen navigation button change state to switch some text.</p>
  
  <p>multipule selection , there is no navigation pop return.</p>
  
  <p>no async function, InheritedWidget seems not any update event.</p>
  
  <p>I never found global variable onChange Listener, May be I should know.</p>
  
  <pre><code>import 'package:flutter/material.dart';
  
  class SandBoxScreen extends StatefulWidget {
      @override
      SandBoxState createState() =&gt; SandBoxState();
  }
  
  class SandBoxState extends State&lt;SandBoxScreen&gt; with TickerProviderStateMixin {
      @override
      void initState() {
          super.initState();
      }
      bool isSelected = false;
      @override
      Widget build(BuildContext context) {
          String nextText = isSelected ? 'next' : 'plz select';
          return new Scaffold(
              appBar: AppBar(),
              body: new Container(
                  child:Column(children: &lt;Widget&gt;[
                      _MenuSelection(),
                      Row(
                          mainAxisAlignment: MainAxisAlignment.spaceAround,
                          children: &lt;Widget&gt;[
                              RaisedButton(child:Text('prev')),
                              RaisedButton(child:Text(nextText)),
                          ],
                      )
                  ],)
              )
          );
      }
  }
  
  
  class _MenuSelection extends StatefulWidget{
      @override
      _MenuState createState() =&gt; _MenuState();
  }
  class _MenuState extends State&lt;_MenuSelection&gt;{
      List&lt;bool&gt; selection = [false,false,false,false];
      @override
      Widget build(BuildContext context) {
          return Container(child:Column(
              children: &lt;Widget&gt;[
                  CheckboxListTile(value: selection[0], onChanged: (a){setState(() { selection[0] = a; });} , title: Text('item1'),),
                  CheckboxListTile(value: selection[1], onChanged: (a){setState(() { selection[1] = a; });} , title: Text('item2'),),
                  CheckboxListTile(value: selection[2], onChanged: (a){setState(() { selection[2] = a; });} , title: Text('item3'),),
                  CheckboxListTile(value: selection[3], onChanged: (a){setState(() { selection[3] = a; });} , title: Text('item4'),),
              ],
          ));
      }
  }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/EMbXV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EMbXV.png" alt="enter image description here"></a></p>