BuildContext scoping in flutter

example.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: MyHomePage(),
    );
  }
}

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

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            Center(
              child: Builder(
                builder: (context) => FlatButton(
                  onPressed: () {
                    Scaffold.of(context)
                        .showSnackBar(SnackBar(content: Text('Hello 1')));
                  },
                  child: Text('Show snackbar (works)'),
                ),
              ),
            ),
            Center(
              child: FlatButton(
                onPressed: () {
                  Scaffold.of(context)
                      .showSnackBar(SnackBar(content: Text('Hello 2')));
                },
                child: Text('Show snackbar (does not work)'),
              ),
            )
          ],
        ),
      ),
    );
  }
}