The S II employs the TouchWiz 4. 0 user interface, following the same principle as TouchWiz 3. 0 found on the Galaxy S, with new improvements, such as hardware acceleration. It also has an optional gesture-based interaction called "motion" which (among other things) allows users to zoom in and out by placing two fingers on the screen and tilting the device towards and away from themselves to zoom in and out respectively. This gesture function works on both the web browser and the images in gallery used within this device. "Panning" on TouchWiz 4. 0 allows the movement of widgets and icons shortcuts between screens, by allowing the device to be held and moved from side to side to scroll through home screens. This gesture-based management of widgets is a new optional method next to the existing method of holding and swiping between home screens. The Android 4. 1 update backports the TouchWiz Nature interface and other features from the Galaxy S III, such as Direct Call, Pop-up Play, Smart Stay, and Easy Mode.