[Seaside] Advice on managing html IDs

[itsme213]

I have two SU components on the same page, and want drag/drop/sortable 
behavior between them. I believe this requires the sortable in one component 
to be parameterized (via #containment: ...) by the ID of the sortable in the 
other component.

I am currently generating this id using "html nextId".

How should I manage the ID? How / when to pass it around to the sibling 
component? Is there a better way?

Thanks!

Sophie