Multiple root items

[LeviticusMaximus]

If I have multiple root items, is there a way to use vertical placement style (eg top) and then stack the trees also vertically? Currently I have two trees A and B that are being laid out side by side

   A               B
a0 - a1         b0 - b1

And I would like to display as such

   A
a0 - a1   

   B
b0 - b1

[BasicPrimitives]

It is possible. Create invisible root item and set its children into vertical formation. Unfortunately there is minor layout bug, the last hierarchy is gonna be shifted to the left.
Look at the matrix layout of the root items: https://www.basicprimitives.com/usecases/multiplerootitemsinchart
Change formation of the root's children into vertical.