Android O will mark the end of apps that draw over System UI as Google is deprecating the UI used by such apps. Instead, it will now be offering developers with a new ‘TYPE_APPLICATION_OVERLAY’ API that will only allow them to draw over other apps.
The System UI of Android consists of the status bar, keyboard, lock screen, navigation bar, and other parts of the system. The existing ‘TYPE_SYSTEM_OVERLAY’ API will be deprecated which will lead to apps like Material Status Bar, Status, Clean Status Bar, and PowerLine from working on Android O. As seen in the screenshot above, using any app that draws over the status bar/system UI in Android O leads to a garbled UI.
At the moment, there is no workaround to this problem, with even compiling apps with a lower target API level not working in the first developer preview of Android O.
Unless you use any of the apps that I mentioned above, this is not a change that will affect you greatly. However, if you use an app that draws over the system UI, you will probably have to bid them adieu once Android O drops since, without an official API, these apps are unlikely to work on the next version of Android. And with no proper API support, developers of such apps are bound to stop their development work on them.
The developers of the above apps did create an issue for the deprecated API on Google’s bug tracker, but a Googler confirmed that this was an intended change from the company’s part.