No virtual folder Unread Messages

Since the completely revised version there is no longer the virtual folder Unread Messages. Up to version 5.6 I could see all unread messages with it, regardless of the folder in which they were stored. Since I have messages delivered directly to various folders and not just to my inbox, this is an indispensable function for me and one of the main reasons for using K-9 at all.
Can that be built in again?