title: How to add an element to the pull down notification bar of an existing app?
body: <p>I want to add a mark as read option to the pull down notification bar of Gmail but I don't have the slightest clue about where to start. If somebody can tell me how to do it or point me in the direction of the right docs to pull it off it would be much appreciated.</p>
  
  <p>I know it is possible because it <a href="https://play.google.com/store/apps/details?id=com.samay.markasread2&amp;hl=en" rel="nofollow">has already been done</a>, but I want to do it by myself.</p>