How To Use Screen Pinning - Android Lollipop

You can enable your device to only show a certain app's screen using screen pinning. Screen pinning can be handy if you want to play a game without accidentally minimizing the app if you touch the Home button. Some apps may ask you if you want to use screen pinning.
When a screen is unpinned, you can choose to return to the screen where you enter your password or PIN.
To pin a screen:
- Go to Settings > Security > Screen pinning and turn screen pinning on.
- Open an app.
- Touch OvervieworRecent on your device. Swipe up the first screen on the bottom to bring it into view.
- Touch the pin. Here, you can select an option to return to the lock screen after a screen is unpinned.
- To exit from the pinned screen, touch and hold Back and Overview or Recent at the same time.