As Rob McDonald wrote on the user list:
"I would like to create a new (empty) database and then tell JabRef to scan my local PDF file collection, automatically creating an (mostly empty) entry for each file.
That way, I will be able to quickly ascertain which of my PDF's have been cataloged vs. which need bibliographic information entered.
Also, by opening the files through JabRef, I should be able to copy & paste this information more quickly.
Furthermore, at a later date, when I toss a few more PDF's into the collection, I would like to be able to re-scan and discover the new files.
My intent is to move to a totally JabRef-centric way of tracking my PDF collection. My current filesystem-based directory hierarchy isn't really cutting it.
So, as an added feature request for this, I would like to automatically assign 'groups' to the discovered files based on the directory names in the filesystem."
I call this feature "find unlinked files":
In scan database I can already find entries that are linked to a file that no longer exits. With this new option I could find a file that is not linked.