[flexcomponents] Using itemRenderer having Dynamic height, in a TileList

[souravwelcomesyou]

I want to use a TileList having an itemRenderer of Dynamic height.

The itemRenderer is a vBox containing a text component. The text 
component gets data from xml using HttpService.

I am getting the textHeight of the text component which is varying 
according to the data from xml, 

       BUT cannot set the value as the rowHeight of the TileList.
Neither can I set the value as the height of vBox..
 

Please Help.