text-list does not need it, even if it accepts if specified. Other faces accept it too, but not all are showing scrollers. And those which are showing (e.g.
text) need to specify
on-scroll actor, and how to manipulate scroller face with its specific facets is undocumented too. So, I think for those we need to wait some explanation.
drop-down it works out of the box. (On W10 at least. I have no info on other platforms.)