title: "Plain Style unsupported in a Navigation Item" warning with my customized Bar Button Item
body: <p>I drag a Round Rect Button to the position of the right Bar Button Item, and set an image to the Round Rect Button. All works well, except the warning "Plain Style unsupported in a Navigation Item". Even if i select the style of the Bar Button Item to "Bordered", warning still be there. What's the matter with Xcode 4.2? Thanks in advance!</p>
  
  <p>Ps. I customized many Bar Button Items with Round Rect Button, some times Xcode 4.2 shows only one warning on a Bar Button Item, some times shows warnings on all Bar Button Items. </p>