Panel caused page background image disappear

Panel caused page background image disappear

Hi - I'm not sure if this is a bug on 1.3-beta.1 on iOS UIWebView html page. I'm using the following simple page:
 
.ui-page { background: url(myimage.jpg) no-repeat; background-size: 1024px 800px};
 
The page:
 
<div data-role="page">
       <div data-role="header">
                sample app
      </div>
       <div data-role="content">
              hello
       </div>
</div>
 
It works fine with proper background image. However, once I added a panel definition:
 
<div data-role="page">
             <div data-role="header">
                      sample app
            </div>
             <div data-role="content">
                    hello
             </div>
 
             <div data-role="panel">
            </div>
</div>
 
the page background is gone and now it shows a full white page. I tried to put something inside the panel but it doesn't change the behavior.
 
All helps are appreciated.