Flex 4 ~ align center

<s:Group horizontalCenter="0" verticalCenter="0"> 
<s:layout>     
<s:HorizontalLayout/> 
</s:layout> 
<s:Button />   
<s:Button />
<s:Button />
</s:Group>


reference
http://stackoverflow.com/questions/1779479/centering-content-in-flex-4