title: React Native React Navigation Header Button Event
body: <p>Hello I 'm trying to bind a function in my Navigator Right Button,</p>
  
  <p>But It gives error. </p>
  
  <p>This is my code:</p>
  
  <pre class="lang-js prettyprint-override"><code>import React, { Component } from 'react';
  import Icon from 'react-native-vector-icons/FontAwesome';
  import Modal from 'react-native-modalbox';
  import { StackNavigator } from 'react-navigation';
  import {
     Text,
     View,
     Alert,
     StyleSheet,
     TextInput,
     Button,
     TouchableHighlight
  } from 'react-native';
  
  import NewsTab from './tabs/news-tab';
  import CustomTabBar from './tabs/custom-tab-bar';
  
  export default class MainPage extends Component {
      constructor(props) {
          super(props);  
      }
  
      alertMe(){
          Alert.alert("sss");
      }
  
      static navigationOptions = {
          title: 'Anasayfa',
          headerRight: 
              (&lt;TouchableHighlight onPress={this.alertMe.bind(this)} &gt;
                  &lt;Text&gt;asd&lt;/Text&gt;
               &lt;/TouchableHighlight&gt;)        
      };
  
      render() {
          return(
              &lt;View&gt;
  
              &lt;/View&gt;
          );
      }
  }
  </code></pre>
  
  <p>And Get error like this:</p>
  
  <p>undefined is not an object (evaluating 'this.alertMe.bind')</p>
  
  <p>When I use this method in render function it is working great but in NavigatonOption I cant get handled it. what can I do for this problem. </p>