Or you could just push F11...
I get the feeling it's intended more for presenting than for actual browsing.
Btw, this PlainView app appears to be 2 years old. How is this getting upvoted?
And there is a "Kiosk mode" which would prevent me from doing an alt+tab. To come out of kiosk mode I would have to type my password once. When the password prompt comes up I would ask myself once if I need to really go to some other app now, or if I should continue concentrating on reading this for more time. This process makes me concentrate longer on what I'm reading.