title: Flex list control itemrenderer issue
body: <p>I am working on a small photo Gallery. I create a xml file and try to link it to my List control with itemrenderer. However, when I tried to save the file, I got access of undefined property "data" error. I thought we are suppose to use "data" to refer the current row of the data object. Here is my code...and thanks a lot!</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600"&gt;
   &lt;fx:Declarations&gt;
    &lt;fx:Model id="pictureXML" source="data/pictures.xml"/&gt;
    &lt;s:ArrayList id="pictureArray" source="{pictureXML.picture}"/&gt;
   &lt;/fx:Declarations&gt;
  
  
  
   &lt;s:List id="pictureGrid" dataProvider="{pictureArray}" 
     horizontalCenter="0" top="20"&gt;
    &lt;s:itemRenderer&gt;
     &lt;fx:Component&gt;
      &lt;s:HGroup&gt;
       &lt;mx:Image source="images/big/{data.source}" /&gt; // where the error happen
       &lt;s:Label text="{data.caption}"/&gt; // where the error happen
      &lt;/s:HGroup&gt;   
  
     &lt;/fx:Component&gt;
    &lt;/s:itemRenderer&gt;
   &lt;/s:List&gt;
  
  
  &lt;/s:Application&gt;
  </code></pre>
  
  <p>My xml </p>
  
  <pre><code>&lt;?xml version="1.0"?&gt;
  &lt;album&gt;
     &lt;picture&gt;
     &lt;source&gt;city1.jpg &lt;/source&gt;
     &lt;caption&gt;City View 1&lt;/caption&gt;
     &lt;/picture&gt;
      &lt;picture&gt;
     &lt;source&gt;city2.jpg &lt;/source&gt;
     &lt;caption&gt;City View 2&lt;/caption&gt;
     &lt;/picture&gt;
       &lt;picture&gt;
     &lt;source&gt;city3.jpg &lt;/source&gt;
     &lt;caption&gt;City View 3&lt;/caption&gt;
     &lt;/picture&gt;
      &lt;picture&gt;
     &lt;source&gt;city4.jpg &lt;/source&gt;
     &lt;caption&gt;City View 4&lt;/caption&gt;
     &lt;/picture&gt;
      &lt;picture&gt;
     &lt;source&gt;city5.jpg &lt;/source&gt;
     &lt;caption&gt;City View 5&lt;/caption&gt;
     &lt;/picture&gt;
      &lt;picture&gt;
     &lt;source&gt;city6.jpg &lt;/source&gt;
     &lt;caption&gt;City View 6&lt;/caption&gt;
     &lt;/picture&gt;
      &lt;picture&gt;
     &lt;source&gt;city7.jpg &lt;/source&gt;
     &lt;caption&gt;City View 7&lt;/caption&gt;
     &lt;/picture&gt;
      &lt;picture&gt;
     &lt;source&gt;city8.jpg &lt;/source&gt;
     &lt;caption&gt;City View 8&lt;/caption&gt;
     &lt;/picture&gt;
      &lt;picture&gt;
     &lt;source&gt;city9.jpg &lt;/source&gt;
     &lt;caption&gt;City View 9&lt;/caption&gt;
     &lt;/picture&gt;
      &lt;picture&gt;
     &lt;source&gt;city10.jpg &lt;/source&gt;
     &lt;caption&gt;City View 10&lt;/caption&gt;
     &lt;/picture&gt;
  &lt;/album&gt;
  </code></pre>
  
  <p>I appreciate any helps!!!</p>