title: Drawer navigator nested inside stack navigator
body: <p>I have a Drawer nested inside of the stack. Unable to implement the back button using it. Can anyone provide a clean solution to resolve this =(</p>
  
  <p>I want to show back button on top on iOS and on android navigate to last screen using hardware back button.</p>
  
  <p><strong>Drawer Navigator</strong></p>
  
  <pre><code>/* @flow */
  
  import React from "react";
  import { DrawerNavigator } from "react-navigation";
  
  import Home from "./components/home/";
  import SplashPage from "./components/splashscreen/";
  import SideBar from "./components/sidebar";
  import Contact from "./components/Contact/";
  
  
  
  const Drawer = DrawerNavigator(
    {
     Home: { screen: Home },
      Contact: { screen: Contact},
    },
    {
      navigationOptions: {
        gesturesEnabled: false
      },
    initialRouteName: "Home",
      contentOptions: {
        activeTintColor: "#e91e63"
      },
      drawerPosition: 'right',
      contentComponent: props =&gt; &lt;SideBar {...props} /&gt;
    }
  );
  
  
  
  export default Drawer;
  </code></pre>
  
  <p><strong>Stack Navigator</strong></p>
  
  <pre><code>/* @flow */
  
  import React from "react";
  
  import { Platform } from "react-native";
  import { Root } from "native-base";
  import { StackNavigator} from "react-navigation";
  import Drawer from "./Drawer";
  import Contact from "./components/Contact"
  import Register from "./components/Register"
  import Home from "./components/home/";
  
  const AppNavigator = StackNavigator(
      {
          Drawer: {screen: Drawer},
         Home: { screen: Home },
          Register: {screen: Register},
      },
      {
          initialRouteName: "Home",
             headerMode: Platform.OS == "android" ? "none" : "float",
          header: (navigation) =&gt; ({
              left: (
                  &lt;Button
                    title="Back"
                    onPress={ () =&gt; navigation.goBack() }  
                  /&gt;
                )
            })
      }
  );
  
  export default () =&gt;
      &lt;Root&gt;
          &lt;AppNavigator /&gt;
      &lt;/Root&gt;;
  </code></pre>