我有以下几点：

import React from 'react';
import { StyleSheet, Text, View, Button } from 'react-native';
import { StackNavigator } from 'react-navigation';

class HomeScreen extends React.Component {
  render() {
    const { navigate } = this.props.navigation;
    return (
      <View>
        <Text>Hello, Chat App!</Text>
        <Button
          onPress={() => navigate('Chat')}
          title="Chat with Lucy"
        />
      </View>
    );
  }
}

class ChatScreen extends React.Component {
  render() {
    return (
      <View>
        <Text>Chat with Lucy</Text>
      </View>
    );
  }
}

const SimpleApp = StackNavigator({
  Home: {
    screen: HomeScreen,
    navigationOptions: {
      title: 'Home'
    },
  },
  Chat: {
    screen: ChatScreen,
    navigationOptions: {
      title: 'Chat with Lucy'
    }
  },
});

export default class App extends React.Component {
  render() {
    return <SimpleApp />;
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center'
  }
});

上HomeScreen有一个头，现在看起来是这样的：

如何隐藏此标题？我只想要一个空白屏幕，或者在这种情况下，只<Text>Hello, Chat App!</Text>需要显示？