Hi,
I think what roundcube needs badly is a way to quickly and temporarily hide the preview pane. I often find spam messages in my Inbox that SA has not caught (different story). When I click to drag them into the Spam folder, they are loaded in the preview pane, which bothers me.
There should be a button to quickly hide the preview pane so I can drag mail without it being loaded. I'm gonna make a ticket for this, too.
Cheers, ~Mik