How to get clickable UMG in the VR Spectator Camera?

Hi there,
That’s kinda interresting, any infos from Epic would be fine… It’s written in the doc “Additionally, enabling Spectator Mode means that you can observe (or, in certain scenarios, interact) with the VR experience while a player uses a HMD in a VR environment.” It would be nice to know these “certain scenarios” !
Actually I only get success in adding some keyboard interaction (without UMG), but it’s pretty restricted.