Describe the bug
The title text (aka mouse over text) starts with "undefined", e.g. "undefined This user can send messages in this groupchat". I think it's supposed to be the JID, but that's unavailable in semi-anonymous groupchats.

To Reproduce
Steps to reproduce the behavior:

1. Join a semi-anonymous room as a non-moderator
2. Point at someone in the participant list
3. Wait for

It’d be useful for users to know which version they’re running on.

For the feature Private key transfer #1090 you use Barcodes for verification.
Would it be a good idea to use the same way to verify Public key of contacts and mark this verificated users in contactlist with a green Icon or somewhat (similar to Threema )?

Maybe:
-yellow for "I'm not sure but I trust the key anyway and will verify it by our next beer."
-green for "I have scanned the code of m