title: How can I capture the value of a React-Bootstrap dropdown list?
body: <p>I figured out how to use react-bootstrap to display a dropdown list:</p>
  
  <pre><code>&lt;DropdownButton bsStyle="success" title="Choose" onSelect={this.handleSelect} &gt;
      &lt;MenuItem key="1"&gt;Action&lt;/MenuItem&gt;
      &lt;MenuItem key="2"&gt;Another action&lt;/MenuItem&gt;
      &lt;MenuItem key="3"&gt;Something else here&lt;/MenuItem&gt;
  &lt;/DropdownButton&gt;
  </code></pre>
  
  <p>But how am I suppose to write the handler for onSelect to capture the option being selected? I tried this but don't know what to write inside:</p>
  
  <pre><code>handleSelect: function () {
      // what am I suppose to write in there to get the value?
  },
  </code></pre>
  
  <p>Also, is there a way to set an option to be selected by default?</p>
  
  <p>Thank you!</p>