title: ShowDialog using children is deprecated how to use it the other way?
body: <p>I am trying to use showDialog in the following manner</p>
  
  <pre><code>showDialog(context: context,child:new Text("Hello Dialgo"));
  </code></pre>
  
  <p>The above works fine however it states that <code>child</code> parameter has been deprecated and the alternative way is to :</p>
  
  <blockquote>
    <p>'Instead of using the "child" argument, return the child from a
    closure '
        'provided to the "builder" argument. This will ensure that the BuildContext '
        'is appropriate for widgets built in the dialog.'</p>
  </blockquote>
  
  <p>I am not sure what that means. Any simple example here would be appreciated.</p>