I found another small glitch.
To reproduce the problem open the account registration wizard window (for an XMPP account) and select the Security tab. Then click on the advanced settings label to open the panel with advanced encryption settings. I attached a screenshot to show what I see before and after the last step (notice the empty zone above the "enable support to encrypt calls" checkbox and the too short cipher suites box).
If I follow the same steps for a SIP account and then do that again for the XMPP account without restarting Jitsi I cannot see the glitch anymore.
I'm on openSUSE 12.1 with KDE 4.9 and openjdk 1.6.