title: NavigationExperimental Can't render overlay
body: <p>Is it possible to render overlay with NavigationTransitioner ? </p>
  
  <pre><code>&lt;NavigationTransitioner
      navigationState={this.props.navigationState}
      configureTransition={this.configureTransition}
  </code></pre>
  
  <blockquote>
    <p>renderOverlay={this.renderOverlay}</p>
  </blockquote>
  
  <pre><code>    render={() =&gt; (
        &lt;NavigationCard
          navigationState={this.props.navigationState}
          renderScene={this.renderScene}
          cardStyle={styles.container}
          onNavigateBack={this.routeBack}
        /&gt;
      )}
    /&gt;
  </code></pre>