It was a bug. Fixed in 3.2.1 CR5
I have downloaded 3.2.1CR5
Problem is still there.
If the scroller and table are inside an <a4j:outputPanel ajaxRendered="true"
it does not scroll.
remove the outputPanel and it works OK.
I need the panel and don't understand why this does not work.
so, removing a4j:outputPanel is a good idea. Why you need to duplicated one ajax with other one?
Because there are other components that need ajax support in the panel.
just get todays build and checked by wrapping example demo page to ajax-rendered outputPanel. Works for me fine.