Head Up notifications is one of these upcoming features that Android developers hid deep in the Android KitKat source code. It was discovered by the custom ROM community not too long ago, and nearly simultaneously ported to the majority of popular ROMs. This method of notifications has also been introduced as a standalone application and an Xposed Framework module.

One of the most interesting alternatives to this built in hidden code was recently released by XDA Recognized Developer AChep. HeadsUp is a fork of the quite popular AcDisplay application. The developer made quite a few improvements to make it a very nice looking and--even more importantly--functional application.

With HeadsUp, you can decide what kind of notifications should be displayed. They can be filtered by priority. For example, the app could be set to display only missed calls as a notification. You can disable notifications for selected applications, so it's much easier for you to which of them should use Heads Up as a default type of notification.

The application will run with every Android version starting from Jelly Bean 4.1. This application doesn't require root access, so it can be used on every device without voiding your warranty or tripping the Knox flag. You can also verify the source code, because this project is fully open-sourced and licensed under the GPL.

This new type of notification is just one click away. All you need to do is visiting the HeadsUp application thread.