It's based on hz-v3.9.2. https://github.com/NeXTHorizon/hz-source/releases/tag/hz-v3.9.2 (announcement coming soon)
HZng - Horizon core with a Nxt GUI - is a personal project. It's not an official hz client, but is correctly recognized by the node bounty program of HZ.
You will get payments for running a hallmarked public HZng node.
Please report bugs related to HZng on bitbucket:
https://bitbucket.org/MattWo/hz-nxtgui/issues?status=new&status=open
Please keep working on this personal project. It's 100x better than the official client.
In fact, the official gui will change with 4.0
You can get a preview on our public node at http://api.nhzcrypto.org:7776