Flex component - vbox vs group why does one compile, other does not?

Trying to understand why when creating a component in flex (flash builder 4) I am unable to create a component from file->new component and reference "data.", but a slightly different sample works. This component is going to be used as an advanced data grid renderer.

This one compiles fine:

<mx:VBox xmlns:fx="http://ns.adobe.com/mxml/2009" 
     xmlns:s="library://ns.adobe.com/flex/spark" 
     xmlns:mx="library://ns.adobe.com/flex/mx" height="100%" width="100%" >
    <s:RichText text="{data.presentingProblemNotes}"/>
</mx:VBox>

This one does not compile, does not like the data.presentingProblemNotes

<?xml version="1.0" encoding="utf-8"?>
<s:Group xmlns:fx="http://ns.adobe.com/mxml/2009" 
         xmlns:s="library://ns.adobe.com/flex/spark" 
         xmlns:mx="library://ns.adobe.com/flex/mx" width="100%" height="100%">
    <s:RichText text="{data.presentingProblemNotes}"/>
</s:Group>

The error is on t开发者_开发技巧he "data" variable - that it does not exist.

In mx components, all UIComponent had a 'data' property which was used for item renderers, but that has been removed in Spark components because not all of them needed it. They now need to extend DataRenderer for it to work. In your particular case, you could do this instead:

<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" width="100%" height="100%">
    <s:RichText text="{data.presentingProblemNotes}"/>
</s:ItemRenderer>