title: this.props.navigation.setParams() doesn't updates parameters from navigation which were passed previously
body: <p>I am using a <code>TabNavigator</code> in my react-native project, and pass some data between the screens via <code>this.props.navigation.setParams()</code>, and respectively <code>this.props.navigation.getParam()</code>. The problem is that this approach works for me, only when I send that data for the first time, second time when I try to send the data, when leaving the screen the data doesn't update in <code>navigation.state.params</code></p>
  
  <p>Here are fragments of code responsible for receiving, and sending data</p>
  
  <pre><code>import {NavigationEvents} from 'react-navigation';
  
  ...
  
  receiveData = () =&gt; {
      if (this.props.navigation.state.params.data !== null) {
          const data = this.props.navigation.getParam('data');
          this.setState({data});
      }
  }
  
  sendData = () =&gt; {
      const {data} = this.state;
      this.props.navigation.setParams({data});
  }
  
  render(){
  
  ...
  
  &lt;NavigationEvents
      onWillFocus = {this.receiveData}
      on WillBlur = {this.sendData}
  /&gt;
  
  ...
  
  }
  
  </code></pre>