KVM: cross cluster migration - hidden feature?

[ingox]

I have two cluster running KVM and I have multiple storages (NFS) where some are zone wide and some are cluster wide.

By using the CloudStack UI I cannot migrate across cluster. I'm not able to select the host(s) on the other cluster.
The documentation says that is not possible: https://docs.cloudstack.apache.org/en/latest/adminguide/virtual_machines.html#moving-instances-between-hosts-manual-live-migration

By using cloudmonkey I can migrate between clusters online. In case of cluster wide storage I need to migrate the storage too. No issues here.

It sounds like a UI bug but documentation would also need to change.

What is your experience?