Folders with special characters, especially accents (like éèà), are listed correctly in the files folder tree of roundcubemail. However when selecting such a folder, it will not be retrieved and roundcubemail will rescan the full folder tree. This does not happen in the chwala interface. Modifying the Base64.decode function in /usr/share/roundcubemail/public_html/assets/program/js/common.js to return atob(Input) instead of utf8_decode(atob(input)) appears to work as a work-around, although I'm not sure it is fully correct.