title: valuenotifier not updating the widget on udating the list
body: <pre><code>import 'package:flutter/material.dart';
  import '../../Data/Globalvariable.dart' as global;
  
  class MenuBar extends StatefulWidget {
    final key = UniqueKey();
    // final pin;
    // MenuBar({this.pin='112'});
    @override
    _MenuBarState createState() {
      return _MenuBarState();
    }
  }
  
  class _MenuBarState extends State&lt;MenuBar&gt; {
    ValueNotifier&lt;List&lt;String&gt;&gt; st = ValueNotifier(global.pincode);
    Widget total() {
      return ListView.builder(
        itemCount: global.pincode.length,
        itemBuilder: (context, index) {
          final item = global.pincode[index];
          return Dismissible(
            key: UniqueKey(),
            onDismissed: (direction) {
              setState(() {
                global.pincode.removeAt(index);
              });
              ScaffoldMessenger.of(context)
                  .showSnackBar(SnackBar(content: Text('$item Removed')));
            },
            background: Container(color: Colors.red),
            child: ListTile(
              title: Text(item),
            ),
          );
        },
      );
    }
  
    @override
    Widget build(BuildContext context) {
      return ValueListenableBuilder(
        builder: (context, n, menu) {
          print(global.pincode);
          return total();
        },
        child: total(),
        valueListenable: st,
      );
    }
  }
  </code></pre>
  <p>this is my main file  i have a global file
  and all of my working variables are there</p>
  <pre><code>Globalvariable.dart
  
  library project.globals;
  List&lt;String&gt; pincode = ['Select Pin','110084','110088'];
  </code></pre>
  <p>now as i am adding data into pincode valuenotifier should listen to it and update the widget automatically but it is not doing so i verified that using debug console it gets updated when i call setstate which is ok but i want to update widget as i add data to my list</p>
  <p><a href="https://i.stack.imgur.com/6E2hv.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6E2hv.jpg" alt="enter image description here" /></a></p>
  <p>this is to demonstrate what i said above that wigdet is updating on removal but not for addition</p>