Window resizing s7

[AC Question]

I have an s7. I went to pull down the notification bar and it made the current app go into a smaller mode where I could move it around the screen same as when you're doing split screen. Happened when I was using Chrome as well as the messages app, couldn't figure out how to do it again. Anyone know how to do this?

 

[chanchan05]

Pull downward diagonally from the upper corner of the app near the notification bar.