Having bezels on a smartphone never really bothered me -- but these days, it seems like almost every manufacturer is trying to get rid of them.

Vivo is at the center of it all, having unveiled a prototype phone with a fingerprint sensor embedded into the touchscreen at this year’s CES. Now the company has taken the bezel-less idea a step further at Mobile World Congress with a new concept phone, Apex.

The front of the phone is all screen. Not "mostly" screen, like most smartphones -- on Apex, the screen takes up the entire front of the device, meaning no space for a fingerprint sensor, speaker, or front camera.

So where did they put the front camera if it's not on the front of the phone? Vivo’s answer: Inside the phone! 

When you try to take a selfie, the camera pops up from the top of the device. Once you return to the rear camera, it retracts automatically. All of that happens smoothly, in about one second -- and it's pretty cool to see.

The selfie camera on Vivo's concept phone pops up when you need it (via GIPHY)

Another question: Where's the earpiece? That's not in the screen... instead, the screen itself is the speaker, vibrating to create sound. And it worked pretty well, with consistent volume throughout the entire screen. I didn’t have to press the phone to my face to listen clearly -- so hopefully this means no more oily screens.

Like Vivo's previous prototype at CES, the Apex concept also has a fingerprint reader built into the screen itself. But where the CES prototype could only scan a small area (about the size of a thumb), here it's much bigger, covering about a third of the screen. It’s also moved slightly higher than where the fingerprint sensor is typically located (towards the bottom of the phone). When you think about it, that’s actually a more natural place for your thumb.

The Vivo concept phone's fingerprint sensor occupies a third of the screen

It sounds great... but it doesn't quite work as well as I hoped. During my 15 minutes with Apex, it almost always required a second or third try before the phone unlocked. Even when it did work, the sensor was noticeably slower than the one I have on my iPhone. This is one element of the Apex phone that definitely isn't ready.

But that isn't something you should worry about, because you can't get your hands on the Apex phone yet -- because it's just a concept device. Vivo says there's no timeline for when it will be released as a retail product. But it's clear that phones like this are the future, and Vivo does have novel solutions to some of the issues facing bezel-free phones.