How to enable Android M's coolest secret feature

One feature we were hoping Google would show off with Android M on Thursday was the inclusion of multi-window functionality that would let you have multiple apps open at once on the same screen. While that sadly didn’t come to pass, Android Authority has done some fine detective work and has discovered a hidden multi-window feature in the Android M developer preview that Google never mentioned during its big Google I/O presentation. Even better, the website has put together a guide for enablin...