Facebook is exploring tabbed UI, perhaps because publishers no longer “like” Stories. First spotted by 9to5Google, Facebook prototype FF811 displays both Most Recent and Seen Facebook stories on a single feed.

By default, Most Recent is featured at the top of your News Feed, but you can either switch to “Most Recent” or be given a pop-up icon to pin it there. See Facebook stories feature Most Recent which shows Stories you might have missed or You Are There.

Those icons also control what Facebook makes visible in your Right Profile picture section, so you’ll have to set Your profile to see Less (Most Recent) or Most Recent content. It’s just a mockup, so it could lead to changes to algorithmically surface stories from the likes of publishing partners.

See stories from others that you might have missed or those you shared when you made the Top News button accessible via thumb down when you most recently shared a story to give yourself a quota of it. But when you see a News Feed story, it won’t be as prominent as Posts and Comments, so you’ll have to click or tap it to add it to your profile. But if you then Like it, your profile will be overloaded with stories from the Like button.

It’s important to remember that Facebook has plenty of data on how people view content. So while this is Facebook poking around, it may not look the same as its existing News Feed layout. We’ve reached out to Facebook and will update if we hear back.

Most Recent sounds like Facebook is searching for another way to get content to appear in your feed. If clicked, the Top Stories button would be a powerful new way to see messages from friends and what’s been shared to Pages, driving page traffic from likes. It could make it easier to discover what others are loving and to get suggested content.

Lastly, seeing Story previews would make sure you see the ones you liked more before viewing them when you swiped through the full story. If it worked in the Facebook you used to see, it would make discovering content easier. And it could get publishers to produce their most-liked content — one of the ways Facebook drives subscriber acquisition.

Still, this image looks like it could end up being an experimental design. Instead of pushing it to the top of the News Feed, Facebook’s Design team may opt to make it an option to display in the Right Profile pictures section.

A top priority is less annoying engagement buttons that prompt a key in or out gesture to access them. Facebook’s “peek view” is its best effort, and features You Are There which sees your Timeline and People icons only a notch below those to the right. But that layout needs to be smooth and intuitive.

For example, it’s already been rumored that Facebook may be testing videos with inline graphic overlays in its feed, giving you a look at the most recent clips but not replacing the placement of the top. There’s probably room for an F8 announcement to clean that up and make it a more accommodating experience.

Either way, the full screenshot seems like it would be an immersive way to find out what’s popular, which is likely what FB wants. And at its annual F8 conference in March, Facebook could present possible new uses for this design to get publishers interested.

Here’s the image found on 9to5Google’s F8 Facebook prototype page that was made available on a placeholder.