Using multi window on the samsung galaxy note 4 is a useful feature for opening 2 screens at once to get more done. I myself have used this feature in the past on previous galaxy devices and found it to be quite useful. To use this feature go into the setting on your galaxy note 4 and scroll down to multi window and slide it to the right to activate it. Next go back to your home screen and hold down on the back button until the multi window option appears. Once its open hold and drag any 2 applications into the middle of the screen. This will enable you to have lots of different options open on your samsung galaxy note 4 simultaneously.