title: Get state of a child component
body: <p>I am using <a href="https://github.com/mzabriskie/react-draggable" rel="nofollow">react-draggabe</a>. I like the idea of adding functionality to a child component by wrapping it into another like <code>&lt;Draggable&gt;</code> does.
  This component manages its own state which is cool. This way I dont have to care about anything.</p>
  
  <p>However: I need to get the current position of the dragged element when an event occurs (e.g. user clicks a button somewhere in another child component).
  I know I could use the onStop-handler and save the new position in the state of the parent elemet. But thats a problem: I duplicate the state of the draggable component because I also save it in the parent. I dont want to do that.</p>
  
  <p>What is the react-way of doing this?<br>
  I am new to rect and this thinking so I would be thankful for a good explanation.</p>