First of all, needless to say this is not the complete halo available in Paranoid. It doesn't offer you that much features but even though you can have the awesome popup window - using the Xposed Framework only! Let's see some pics:
As you can see on the pictures, Halo offers you a movable and resizable windows that can be dragger (moved), resized, or if you want - you can set its transparency. More options will be added in future, obviously.
The entire app needs the Xposed Framework (and therefore root access) so if you don't know what it is (or don't have it yet), check THIS post to get more info and a download link.
I don't have root! :(
Unfortunately, the Halo does not really work without root access. On the bright side, you can get some similar (though very usefull, too!) apps such like Floating Notifications - available for free on Google Play!