title: react-navigation Drawer lock dynamically
body: <p>How to lock the drawer dynamically ? I have a modal use from <a href="https://github.com/maxs15/react-native-modalbox" rel="nofollow noreferrer">react-native-modalbox</a>. When I open up the modal, I  call this <code>this.refs.modal.open();</code> and locked the drawer. I only know that <code>drawerLockMode</code> can set in <code>navigationOptions</code>. But modal is not a screen in <code>DrawerNavigator</code></p>
  
  <pre><code>const MainDrawer = DrawerNavigator({
      Event: { screen: EventScreen },
      Wallet: { screen: WalletScreen},
      Profile: { screen: ProfileScreen},
      Contact: { screen: MemberContactScreen},
      Reward: { 
        screen: MemberRewardScreen,
        navigationOptions:{
          drawerLockMode :'locked-closed'
        }},
  },{
    contentComponent: props =&gt; &lt;DrawerScreen {...props} /&gt;
  });
  </code></pre>