the CHANGELOG for Roundcube Webmail says there is support for IMAP MOVE extension [RFC 6851] since 1.0.0-beta. So how do I setup Roundcube in order to move some messages from one account to another?
You need share destination mailbox (SETACL) and move as usual.
"While
not fully understand a software, don't try to adapt this software to
the way you work, but rather yourself to the way the software works"
(myself)