Scroll a CellTree if expanded?

[membersound]

Hi,

I have a CellTree with few root items and each having a lot of childs. When I expand a node, I can click "show more", which will then expand the rest of the data invisible down below.
I'm not getting any scrolling controls. Only thing I can do is tap down with the keyboard.

How can I add a ScrollPanel / scrolling ability to a expanded CellTree if data goes beyond the Panel borders?

Thanks