Samsung Galaxy S6 User Manual page 51

Note: Only applications that support Multi window have the
Multi window icon.
Window Controls
Tap Window controls in the middle of the window border.
Switch windows: Switch locations between Multi window
apps.
Drag and drop content: Move items between the app
windows. Drag an item to share from one window to another.
Not all applications support this feature.
Minimize window: Minimize the selected app window. This
turns the app into a circular, movable icon that can be opened
by tapping on it.
Maximize window: Open the selected app window in full
screen view.
Close app: Close the selected app.
Know Your Device 39 Multi Window