Samsung rolled out its Multi Window feature for Galaxy S3 in its new OTA update (Android 4.1.2). This has been borrowed from Galaxy Note II. Also, the newer phone in galaxy series, Galaxy Grand comes built-in with Multi window.
To enable Multi window is very simple, You can do it from notification bar right away. Scroll the bar right-to-left and at the end, you will find “Multi Window”. Refer the video embedded below.
What is Multi-Window?
Multi Window is Samsung’s signature feature for Android devices, comes built in with Note II. If it is enabled, you can use two apps simultaneously.