bring up the system folder.
Now, you should have multi-window enabled.
To activate it, open a couple of apps, and then tap the multitasking button.
Simply tap this icon and choose where youd like that app to go.
The previous app in your list will fill in the other side.
Right now, this feature isnt very robust, which makes sense.
Its not supposed to be activated by anyone outside Google.
However, its there if youd like to fiddle around with it.
How to Unlock the Hidden Multi-Window Mode in Android 6.0 Marshmallow| WonderHowTo
