still..

http://abload.de/thumb/squirrelmail8rplh.png

With Win7 + Firefox 33 and also Debian sid + Chromium.

Roundcube works, but not perfect. I can open a specific mail and delete it, but the preview (bottom window) won't load nor mass selection and delete of mails. Roundcube tries to load the mail in the preview window but didn't finish. Open the mail with doubleclick works like a charm.

Edit: Option menu in roundcube also won't load. Same effect.