PGP/OTR/OMEMO transfer keys
(I don't know if this feature is conveniento to be a XEP extension)
When someone starts Gajim in one computer "A" and begins to Chat contacts with encryption, client application generates keys for this encryption. Keys are saved locally in this "A" Computer and user profile. When same user starts Gajim in another computer "B" and resumes activity with its contacts with encryption, client application generates new keys for encryption, and user's contacts now see same user with different keys to trust. When user goes back to "A" with first Gajim local data there, others must trust that this is the same contact but with crazy behaviour about keys.
There should some easy (GUI) way to one Gajim instance (A) transfers profile to another Gajim instance (B), online (or export package and send). This should ease an XMPP user to keep a single identity at all. Current behavior does not allow people really trust others knowing what this implies.