title: How should the new context api work with React Native navigator?
body: <p>I created a multiscreen app using React Navigator following this example:</p>
  
  <pre><code>import {
    createStackNavigator,
  } from 'react-navigation';
  
  const App = createStackNavigator({
    Home: { screen: HomeScreen },
    Profile: { screen: ProfileScreen },
  });
  
  export default App;
  </code></pre>
  
  <p>Now I'd like to add a global configuration state using <a href="https://reactjs.org/docs/context.html" rel="noreferrer">the new builtin context api</a>, so I can have some common data which can be manipulated and displayed from multiple screens.</p>
  
  <p>The problem is context apparently requires components having a common parent component, so that context can be passed down to child components.</p>
  
  <p>How can I implement this using screens which do not share a common parent as far as I know, because they are managed by react navigator?</p>