How to use the Multi Window Feature on Samsung Galaxy S9/S9+?
The Multi Window mode on your Samsung Galaxy S9 and S9+ lets you view two apps side by side on a split screen. You can adjust the size of the individual screens and copy information from one app to the other.
With the new One UI (Android 9.0), it is now even easier to be a multi-tasking champion!
• Only applications that supports the Multi Window feature will have option displayed.
Another selection screen will appear for you to choose the second application that you want to multi-task with.