title: Unmount or re-render screen in drawer navigator
body: <p>I just added drawer navigator recently and wrapped my screens in <code>createDrawerNavigator()</code></p>
  
  <p>These are my current routes:</p>
  
  <ul>
  <li>Home.js</li>
  <li>Post.js</li>
  <li>Settings.js</li>
  </ul>
  
  <p>When a user navigates from <strong>Home</strong> to <strong>Post</strong> I pass a param that has the post data.</p>
  
  <pre><code>onPress={() =&gt; this.props.navigation.navigate('Post', {postData: postData})}
  </code></pre>
  
  <p>When ever the user goes back to <strong>Home</strong> from <strong>Post</strong>, then post will be unmounted. and mounted back again with fresh data when another post is clicked.</p>
  
  <p>My issue is that with implementing the drawer, the <strong>Post</strong> screen does not get unmounted when navigating back to <strong>home</strong>, I keep gettings the same props and screen of the first post opened, over and over again.</p>
  
  <p>This is my route setup:</p>
  
  <pre class="lang-js prettyprint-override"><code>import React from "react";
  import { createDrawerNavigator, createStackNavigator, createAppContainer } from 'react-navigation';
  import Home from './screens/Home';
  import Post from './screens/Post';
  import Settings from './screens/Settings';
  import SideBar from './screens/sidebar';
  
  const Drawer = createDrawerNavigator(
  {
      Home: {screen: Home},
      Post: {screen: Post},
      Settings: {screen: Settings}
  },
  {
      initialRouteName: "Home",
      backBehavior: 'initialRoute',
      contentOptions: {
      activeTintColor: "#e91e63"
      },
      contentComponent: props =&gt; &lt;SideBar {...props} /&gt;,
  }
  );
  
  const AppNavigator = createStackNavigator(
      {
      Drawer: {screen: Drawer},
      },
      {
      initialRouteName: "Drawer",
          headerMode: "none",
      }
  );
  
  export default createAppContainer(AppNavigator);
  </code></pre>
  
  <p>What am I doing wrong?</p>
  
  <p>I want each post screen to open and re render as new when navigating to it from Home.</p>