title: Navigation Bar and Tab Bar not showing up together
body: <p>The following code will show the navigation bar and it's navigation works as it should...But the tab bar does not show up at all. Now, if I remove the code that has to do with the navBar, the tab bar is present.</p>
  
  <p>I am a bit new to React-Native, so I bet I am missing something, but I feel I did everything correctly as the tutorial I was following said to do.
  <a href="https://i.stack.imgur.com/lNBgQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lNBgQ.png" alt="enter image description here"></a></p>
  
  <pre><code>import React from 'react';
  import {
      AppRegistry,
      Text,
      View,
      Button,
      WebView
  } from 'react-native';
  import {StackNavigator, TabNavigator} from 'react-navigation';
  
  class HomeScreen extends React.Component {
      static navigationOptions = {
          title: 'Welcome'
      };
      render() {
          const {navigate} = this.props.navigation;
          return(
              &lt;View&gt;
                  &lt;Text&gt;Hello!&lt;/Text&gt;
                  &lt;Button
                      onPress={() =&gt; navigate('Chat')}
                      title="Navigate to new screen"
                  /&gt;
              &lt;/View&gt;
          );
      }
  }
  
  class NewScreen extends React.Component {
      static navigationOptions = {
          title: 'New screen'
      };
      render() {
          return (
              &lt;View&gt;
                  &lt;Text&gt;Welcome to your new screen&lt;/Text&gt;
              &lt;/View&gt;
          );
      }
  }
  
  class WebScreen extends React.Component {
      render() {
          return &lt;Text&gt;Recents&lt;/Text&gt;
      }
  }
  
  class OtherTabScreen extends React.Component {
      render() {
          return &lt;Text&gt;Alternate screen&lt;/Text&gt;
      }
  }
  
  const TabBarNavigator = TabNavigator({
      Web: {screen: WebScreen},
      Other: {screen: OtherTabScreen}
  });
  
  const GivingTrax = StackNavigator({
      Home: {screen: HomeScreen},
      Chat: {screen: NewScreen}
  });
  
  AppRegistry.registerComponent('GivingTrax', () =&gt; GivingTrax);
  </code></pre>