title: How to use backBehavior: 'history' on my bottomtabnaviagor
body: <p>I have a BottomTabNavigator in my Expo app as the initial page. Whenever I navigator to another screen and go back I want to have the last opened tab on the tabnavigator open. I have read that: 'backBehavior: 'history' does just that, but it doesn't work for me, it instead goes to the initialtab. This is my Tabnavigator code: </p>
  
  <pre><code>class MainTabNavigator extends React.Component {
  
  const DiscoverStack = createStackNavigator(
      {
          Discover: DiscoverScreen
      },
      { backBehavior: 'history' }
  );
  
  DiscoverStack.navigationOptions = {
      tabBarLabel: 'Ontdek',
      backBehavior: 'history',
      tabBarIcon: ({ focused }) =&gt; (
          &lt;TabBarIcon
              focused={focused}
              name={`${focused ? 'md-bulb' : 'ios-bulb'}`}
          /&gt;
      )
  };
  
  const TodoStack = createStackNavigator(
      {
          Todo: TodoScreen
      },
      { backBehavior: 'history' }
  );
  
  TodoStack.navigationOptions = {
      tabBarLabel: 'Wat te doen',
      backBehavior: 'history',
      tabBarIcon: ({ focused }) =&gt; (
          &lt;TabBarIcon focused={focused} name={'md-calendar'} /&gt;
      )
  };
  
  const ShopStack = createStackNavigator(
      {
          Shop: ShopScreen
      },
      { backBehavior: 'history' }
  );
  
  ShopStack.navigationOptions = {
      tabBarLabel: 'Shop',
      backBehavior: 'history',
      tabBarIcon: ({ focused }) =&gt; (
          &lt;TabBarIcon focused={focused} name={'md-cart'} /&gt;
      )
  };
  
  const WinStack = createStackNavigator(
      {
          Win: WinScreen
      },
      { backBehavior: 'history' }
  );
  
  WinStack.navigationOptions = {
      tabBarLabel: 'Win',
      backBehavior: 'history',
      tabBarIcon: ({ focused }) =&gt; (
          &lt;Icon2
              focused={focused}
              size={26}
              style={{ marginBottom: -3 }}
              color={focused ? Colors.tabIconSelected : Colors.tabIconDefault}
              name={'ticket'}
          /&gt;
      )
  };
  
  const UserStack = createStackNavigator(
      {
          User: UserScreen
      },
      { backBehavior: 'history' }
  );
  
  UserStack.navigationOptions = {
      tabBarLabel: 'Account',
      backBehavior: 'history',
      tabBarIcon: ({ focused }) =&gt; (
          &lt;TabBarIcon focused={focused} name={'md-person'} /&gt;
      )
  };
  
  export default createBottomTabNavigator(
      {
          DiscoverStack,
          TodoStack,
          ShopStack,
          WinStack,
          UserStack
      },
      { backBehavior: 'history' }
  );
  </code></pre>