Marshmallow now include support for Multi-Window interface but, it's disabled by default. You need a little bit of tinkering to get it to work. -First, you will need to have a rooted device, so make sure you flashed SuperSU 2.62 (older version won't work on Marshmallow). -Then, you will need to edit a single line inside build.prop (located in /system folder), I did this with Root Browser because many other file browsing apps have trouble getting root access with Marshmallow. Root Browser is working perfectly as long as you have the right version of SuperSU. -Once you open build.prop with Root Browser, you need to look for the line "ro.build.type=user", then you will need to change this line to "ro.build.type=userdebug", once it's done, reboot your phone . -Now, you need to enable Developer settings by going in Parameters/About phone and tap on "Build number" seven time. -You will now see the Developer settings in Parameters, open...