> So overall you will need to understand how the runtimes work and if particular pieces can be mixed and matched...

Hm... really?

I was under the impression that it was more correct to say that mixing runtimes is undefined behaviour?

It may work, but just like mutable aliasing using unsafe may not cause memory corruption; it just happens to work in the current implementation, on the current platform, on the current version of rust.

There is no guarantee it will continue to work in the future.

Maybe I misunderstood, but I thought it was a lot more complicated than just starting multiple events loops and you’re fine.