Hi, I saw ticket #1484764 (http://trac.roundcube.net/ticket/1484764) a while ago.
I'd like to see this feature implemented, and I'll try to come up with a patch in a few days.
However, I'm not really sure if it's secure. RC seems to store the user's password in $_SESSION['password'], and it's decrypted whenever the password's needed. Is session data stored on the server or on the client's computer?
It is stored on the server.
Great. I'll start working on it as soon as I have some spare time.