Autohide scrollbars when not scrolling in a ListView
<p>In the new official Twitter app, the scrollbars in all the ListViews the app uses are hidden unless the user is scrolling through the list.  </p>

<p>When you start scrolling, the scrollbars appear.  When you stop, they fade out with an animation until they are gone completely.</p>

<p>I can't seem to find anything in the documentation that indicates this as being a standard feature.</p>

<p>Is this something included in the API?  If not, anyone know how this might be done?</p>
