title: react-navigation drawer open issue
body: <p>I have tried this </p>
  
  <pre><code>this.props.navigation.dispatch(DrawerActions.openDrawer());
  
  this.props.navigation.navigate("toggleDrawer");
  </code></pre>
  
  <p>and </p>
  
  <pre><code>this.props.navigation.navigate("DrawerOpen");
  </code></pre>
  
  <p>but still unable to open drawer from button click which is working from swipe left to right.</p>
  
  <p><a href="https://i.stack.imgur.com/UnFLT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UnFLT.png" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/3w4Xn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3w4Xn.png" alt="enter image description here"></a></p>
  
  <p>and in click event I tried these options.</p>
  
  <p><a href="https://i.stack.imgur.com/KUFEy.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KUFEy.png" alt="enter image description here"></a></p>