title: showModalBottomSheet() not opening a bottom modal in flutter
body: <p>The showModalBottomSheet does not pop up a modal. I am new to flutter and dart but I think this is a problem, I would not any help. The simple page to pop a bottom sheet modal below.. did not work.</p>
  
  <pre><code>```
    import 'package:flutter/material.dart';
  
      void main() =&gt; runApp(new MyApp());
  
     class MyApp extends StatelessWidget {
       @override
        Widget build(BuildContext context) {
  
          return new MaterialApp(
             home: new Scaffold(
               appBar: new AppBar(title: const Text('Modal bottom sheet')),
               body: new Center(
                 child: new RaisedButton(
                  child: const Text('SHOW BOTTOM SHEET'),
                 onPressed: () {
                   showModalBottomSheet&lt;void&gt;(context: context, builder: (BuildContext context) 
                 {
              return new Container(
                child: new Padding(
                  padding: const EdgeInsets.all(32.0),
                  child: new Text('This is the modal bottom sheet. Click anywhere to dismiss.',
                    textAlign: TextAlign.center,
                    style: new TextStyle(
                      color: Theme.of(context).accentColor,
                      fontSize: 24.0
                    )
                  )
                )
              );
            });
          }
        )
      )
    )
  );
  </code></pre>
  
  <p>}
  }
      ```</p>
  
  <p>I cannot seem to figure out what the probl</p>