title: How should I customize DropdownButtons and DropdownMenuItems in Flutter?
body: <p>The default <a href="https://docs.flutter.io/flutter/material/DropdownButton-class.html" rel="noreferrer">DropdownButton</a> with DropdownMenuItems returns a light-grey dropdown. How should I customize the dropdown (e.g. background color, dropdown width)? I can change the <code>style</code> property in both DropdownButton and DropdownMenuItem, like this:</p>
  
  <pre><code>return new DropdownButton(
        value: ...,
        items: ...,
        onChanged: ...,
        style: new TextStyle(
          color: Colors.white,
        ),
      );
  </code></pre>
  
  <p>but this doesn't change the dropdown's background color.</p>
  
  <p>Should I copy DropdownMenu and extend it? Does Flutter plan to add customization for this widget in the near future?</p>