title: Not able to Listen New Value From Bloc Flutter
body: <p>I'm using flutter_bloc library to manage the state of the app, as I press a button in a different class state changes in bloc class but not able to listen in BlocProvider in build method.</p>
  
  <pre><code>BlocBuilder&lt;AppBarBloc, bool&gt;(
            builder: (context, isEnabled) {
              print('state detected');
              return Container();
            },)
  
  //in main.dart were providing the Blocs
  
  
  MultiBlocProvider(
        providers: [
          BlocProvider&lt;PagesBloc&gt;(
            builder: (BuildContext context) =&gt; PagesBloc(),
          ),
          BlocProvider&lt;AppBarBloc&gt;(
            builder: (BuildContext context) =&gt; AppBarBloc(),
          ),
        ],
        child: Column(
          children: &lt;Widget&gt;[
            Expanded(
              child: MaterialApp(
                title: 'Flutter Demo',
                initialRoute: '/',
                onGenerateRoute: RouteGenerator.generateRoute,
                theme: ThemeData(
                  primarySwatch: Colors.blue,
                ),
              ),
            ),
          ],
        ),
      );
  </code></pre>