Security of these new features is something that is being taken very seriously. APIs like the Full Screen API and Mouse Lock API can only be invoked manually by a user, either by clicking something on the screen or pressing a key.

It is also impossible for a website to take control of the Full Screen or Mouse Lock API without your direct knowledge. A big message appears at the top of the screen when in full screen mode and you can always exit it at any time by pressing the Esc key.