Oh and one other thing. If you use RC away from home and Thunderbird at home you might want to be aware of this:
https://bugzilla.mozilla.org/show_bug.cgi?id=220064
It's a Thunderbird bug/feature that's going to look like a Roundcube bug to a lot of people. If you feel inclined vote for it as a bug and leave a comment that it exhibits itself as buggy behavior in webmail clients.
-Charles