how to create Floating window in android
<p>I saw some android applications that has floating window like something in windows OS (or like picture below).I had searched but i could not find any thing.Is any api or library needed or this is just styling?</p>

<p><a href="https://i.stack.imgur.com/SAD94.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SAD94.jpg" alt="Floating window in android"></a></p>