With 0.1.1 and PHP 5.2.6 search was never finding anything.
PHP Warning: join() Invalid arguments passed in roundcubemail-0.1.1/program/include/rcube_imap.inc on line 673
$msgs is already a string from the is_array() test earlier in _list_header_set(). The join in the _fetch_headers() call breaks search for me and its not needed.
$this->_fetch_headers($mailbox, $msgs, $a_msg_headers, NULL)
Johh Capo Tuffmail.com
List info: http://lists.roundcube.net/dev/