title: How to change the direction of the animation in StackNavigator?
body: <p>How to change the direction of the animation in StackNavigator?</p>
  
  <h3>Current Behavior</h3>
  
  <p>When user goes to another screen, the screen flies from <strong>bottom to top</strong>. </p>
  
  <h3>Expected Behavior</h3>
  
  <p>When user goes to another screen, the screen flies from <strong>right to left</strong>. (Like Facebook or Instagram!)</p>
  
  <h3>StackNavigator Code</h3>
  
  <pre><code>export default StackNavigator ({
      Main: {
          screen: MainScreen,
      },
      ...
  }, {
      navigationOptions: ({navigation, screenProps}) =&gt; ({
          tabBarOnPress: blahblaj
      }),
      lazy: true
      // I guess we can do something here
  });
  </code></pre>
  
  <ul>
  <li>If we can set the animation time, it will be even better! Currently it looks like the screen flies from middle of the screen to top. I want natural animation like Facebook or Instagram :)</li>
  </ul>
  
  <p>Thanks in advance, </p>