Is Android getting multi-window support in time for Google I/O?

Android 5.1 is now out in the wild, but it might be holding a few secrets. The diligent folks at Phandroid have dug up something interesting in the code: references to apps running in multiple windows. The change could be announced at Google I/O in May.There's not much detail to go on here - it's essentially just a couple of lines referring to "multiwindows" hidden inside the software - and as yet Google hasn't said anything about what's going to be on show at its developer conference