title: Can't show rounded corners on custom panel skin
body: <p>I'm fairly new to Flex 4.0. I wanted to change the background color of my Panel title area and  I discovered that I needed to create custom skin or skin extender to accomplish this.  So I created a skin called myPanelSkin based upon the Spark.PanelSkin.  My background color works fine but it will no longer show the cornerRadius defined either on the component or in a style.  </p>
  
  <p>I then tried another approach and simply created a new skin as an exact copy of the Spark.PanelSkin. It also looses the cornerRadius.  </p>
  
  <p>Any ideas on how to solve this problem.  It seemed so much easier in Flex 3.  Thanks.  </p>