Yes I've seen that movie already. And it is clear, but not for above situation.
The 'Has items' condition only can be chosen with queries.
Look at my code above: the repeater takes data from the query (q_tsoparents) (and receives data, so it has items!).
But then the repeater itself has a filter: .where(`obo_obopties`, oo_id, "=="
This filter sometimes returns data, sometimes not.
And here I want to use the show or hide dynamic attributes. But that seems not to be possible, since it is not the query that contains no items, but the repeater.