title: React Native call function from navigation
body: <p>I'm using React native navigation. (Stack Navigation).
  But I can't call function in navigationOptions. Not working.</p>
  
  <pre><code>import React, { Component } from 'react';
  import { StyleSheet, View, Text, TouchableHighlight, AsyncStorage, Alert } from 'react-native';
  import { Button } from 'react-native-elements';
  import Icon from 'react-native-vector-icons/FontAwesome';
  import HandleBack from '../../HandleBack';
  
  export default class Dashboard extends Component {
      constructor(props) {
          super(props);
      }
  
      static navigationOptions = ({ navigation }) =&gt; {
          return {
              title: 'Dasboard',
              headerLeft: null,
              headerRight: (
                  &lt;TouchableHighlight underlayColor='transparent' onPress={this.login.bind(this)} style={{marginRight: 10}}&gt;
                      &lt;Icon
                          name="power-off"
                          size={25}
                          color="white"
                      /&gt;
                  &lt;/TouchableHighlight&gt;
              )
          };
      };
  
      login() {
          alert('Button clicked!');
      }
  
      onBack = () =&gt; {
          this.props.navigation.navigate('Screen3');
      };    
  
      render() {        
          return(
              &lt;HandleBack onBack={ this.onBack }&gt;
                  &lt;View&gt;
                      &lt;Text&gt; This is screen 2 &lt;/Text&gt;
                      &lt;TouchableHighlight onPress={() =&gt; this.props.navigation.navigate('Screen3')}&gt; 
                          &lt;Text&gt; Go to Screen 3 &lt;/Text&gt;
                      &lt;/TouchableHighlight&gt;
                  &lt;/View&gt;
              &lt;/HandleBack&gt;
          )
      }
  }
  </code></pre>
  
  <p>When I'm using <code>onPress={this.login.bind(this)}</code> get error </p>
  
  <p><em>"TypeError: TypeError: undefined is not an object (evaluatinh '_class.login.bind')"</em></p>
  
  <p>When I'm using  <code>onPress={this.login}</code> no reaction.</p>
  
  <p>When I'm using <code>onPress={this.login()}</code> get error</p>
  
  <p>TypeError: TypeError: _class.login is not a function.</p>
  
  <p><strong>But</strong></p>
  
  <p>I'm using <code>onPress={() =&gt; alert('test')}</code> is working.</p>