Drawing over other applications in Android [closed]
问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed last year . There is an interesting application called Twilight which appears to simply draw over all applications with a reddish filter to remove blue light during nighttime hours (presumably to help sleep). I'm interested in doing something similar, but not necessarily for sleep purposes. I'd