SlideOver Messaging
This is Jacob Klinker and I's SlideOver Messaging app. It is a part of our Sliding Messaging Project, but we have decided to open source this part of our and put it on the play store for free so that other people can contribute and see how things are done.
The app isn't really being maintained anymore. With Android 5.0+, it won't work at all, because I never updated it to give it the permission to draw over other apps.