Today in the hidden-in-play-sight department, the CyanogenMod team uncovered a dormant feature existing in AOSP code that activates a floating notifications mode. Dubbed Heads Up, the feature is now a part of CyanogenMod 11 nightlies.

The feature has been present in the open source code of Android for a while, but it was only recently that the CyanogenMod team discovered it. We don’t know why the feature was inactive, though it’s possible that Google wanted to enable it in the next major version of Android.

Heads Up shows an actionable notification card on top of the app you were running at the moment. The feature resembles the Hover app from Paranoid Android to an extent, though it lacks the floating window multi-tasking mode.

In effect, Heads Up mode shows the notification cards you would see by swiping down the notification shade. You can interact with the cards in the same way you would with notifications in the dropdown – you can swipe to dismiss or extend the card for further actions.

The CyanogenMod team enhanced the feature by adding a Do Not Disturb function that lets you select the specific apps that you don’t want interrupted by notifications. So if you don’t want any notifications showing on top of your video or game, you can selectively disable Heads Up.

Heads Up mode has been available since last Thursday in CyanogenMod 11 nightlies, available for dozens of devices listed here. The feature will likely make it to the CM11 M8 milestone release, due to roll out in the following weeks.