Why do list s:itemRenderer in sdk 4.5 need a child fx:Component

Question

If I do this
<s:List>
<s:itemRenderer>
<fx:Component>
<s:HGroup >
<s:TextArea text="{data.comment}" height="40">
I get an error  Access of undefined property data

Answer 1

however in an external file you can do this:
<?xml version="1.0" encoding="utf-8"?>
<s:ItemRenderer xmlns:fx="http://ns.adobe.com/mxml/2009"
                xmlns:s="library://ns.adobe.com/flex/spark"
                xmlns:mx="library://ns.adobe.com/flex/mx"
                autoDrawBackground="true">
    <fx:Script>
        <![CDATA[
            import utils.Formatters;
        ]]>
    </fx:Script>
    <s:HGroup width="100%" verticalAlign="middle" paddingRight="10" paddingLeft="10" paddingBottom="5" paddingTop="5">