The ASUS Cover has its own Quick View panel which saves yout time on looking for applicaiton.Quick View panel shows up when you swipe around or long-press onits edges so you can quickly check and switch any applications by icons of panel.
ASUS Cover for ZenFone 2:
ASUS Cover for ZenFone 3:
These icons are also shortcuts for the apps currently enabled on ASUS Cover.
Note: If you use a non-official cover accessory, some function may not work properly. Check out the official ASUS website to see the latest ASUS official cover accessory.