title: Android - How to make activity or layout over other apps?
body: <p>I want to show message to user. But I want to do that like MusiXMatch. I don't know what is component's name. </p>
  
  <p>MusixMatch shows lyrics over the other apps till user close the app or click hide button. I can explain what I want with 2 Images.  </p>
  
  <p><img src="https://i.stack.imgur.com/onINL.png" alt="When app starts, this mini icon will show always. If user clicks on it icon will expanded to Image 2:"></p>
  
  <p><img src="https://i.stack.imgur.com/ObvGB.png" alt="The app shows user to music."></p>
  
  <p>I hope that I can explain what I want. </p>