Check Out Hans’s Article on Spark Viewports and Scrolling
Just a quick note that Hans Muller has started a seriese of articles regarding Flex on his blog. His spiffy article here has some very good info about the Spark Viewports and Scrolling 
Also you can check out how little I had to do to implement scrolling support in a custom layout here.
Enjoy!
I think i’ve seen this somewhere before…but it’s not bad at all