Android 7.0 Nougat will bring multi-window support to Android phones and tablets. But there are already a few custom versions of Android with multi-window capabilities, including Phoenix OS and Jide’s Remix OS.
While Remix OS was initially only available to folks who bought a device with the OS pre-loaded, these days you can download the operating system and run it on a wide range of notebook or desktop PCs with Intel or AMD chips. And you’ve also been able to install it as a custom ROM for some Nexus devices.
Now Remix OS 3.0 is also available for the Google Pixel C and Nexus 9 tablets, which means that Jide is bringing multi-window support to those tablets slightly sooner than Google (which is probably going to release Android 7.0 later this month).
Remix OS 3.0 is the first version of Jide’s operating system to be based on Android 6.0 Marshmallow and also includes some stability enhancements as well as a handful of new features including tools that make it easier to resize windows.
Jide has also added an experimental “Gaming Toolkit” that lets you enable key mapping for playing games in Remix OS.
via xda-developers