Use WindowManager to Create Floating Apps
We’ve seen much in the way of floating apps recently: Facebook’s Chat Heads, the revolutionary Halo interface by the Paranoid Android team, and all of the various floating mini apps that we’ve covered in the past. How would you like to incorporate similar functionality into your own app?
XDA Senior Member EatHeat presents a way to do so with an additional service that runs over all apps using WindowManager. He does so with a fully open source sample application. The example’s floating blob can be tweaked and its location can be changed to anywhere below the status bar. While the sample application targets API 10+ (Gingerbread MR1), EatHeat says that this should work just fine with older Android versions.
While you’re at it, make sure to check out EatHeat’s other guides on Robotium and auto-testing apps, as well as his Simple GridLayout library.. If you’re learning app development or would just like to hone your skills further, they’re more than worth a look.