Only ask for gpg-key's password when needed
Currently gajim asks for the passwords of all gpg-keys on startup and again everytime the configured TTL ends - regardless if there is something to decrypt/sign or not. Furthermore these dialogs are accumualting over time (ie. after the TTL has expired x times you have x password dialogs for each key).
I suggest to only ask for the password iff gajim also needs to use it.
In the meanwhile it is possible to mitigate this problem by setting a very high time to live for the passwords. This may compromise security though.