How to best handle chat type displays

Using a main layout with toolbar at top and having the main layout child as a verticallayout (full size).

How best to handle the case, like a chat application, where many components are added to a view overlaying the child.

It seems I need to set the child layout scrollable with css overlay:auto or the toolbar scrolls up when the components are added. But in my case this is not working as expected.

I am somewhat restricted as I am using OSGi and compatability mode as many features of V14 cannot be used in compatability mode.

I have been thinking of using a single column grid with rows added but this seems a bit of overkill.