I have just installed Roundcube 0.2-beta. (title prefix is wrong, there is no "0.2-beta" prefix)
It seems that it does not show new mails that are delivered in folders other than "Inbox". since I use server side filtering, I get emails directly delivered to different folders, and Roundcube does not update new mail count for folders, even if I click the "Check for new messages" button.
If I reload from the browser "reload" button, then it shows the new mail in every folder properly.
I suggest that new mail should be checked for in every folder, eventually using a configuration option.