Corey Johnson's <a href="https://medium.com/android-news/android-viewoverlays-simple-layering-aa513e28fb81">Android ViewOverlays — Simple Layering</a>
Suneet Agrawal's <a href="https://agrawalsuneet.medium.com/viewoverlay-in-android-c12e43ed4a98">ViewOverlay in Android</a>
Flavien Laurent's <a href="http://old.flavienlaurent.com/blog/2013/08/14/viewoverlay-when-how-and-for-what-purpose/">ViewOverlay: When, How and for What Purpose?</a>
Chet Haase's <a href="http://graphics-geek.blogspot.com/2013/07/new-in-android-43-viewoverlay.html">New in Android 4.3: ViewOverlay</a>

One small bit of android development at a time.