title: NativeSelect wait until I choose an option
body: <p>I'm using a framework named Vaadin, in it I use a NativeSelect, that works like an HTML select. And I want to setVisible(true) when one option is chosen. </p>
  
  <p>Here is my code :</p>
  
  <pre><code>List&lt;String&gt; behaviourData = new ArrayList&lt;&gt;();
  behaviourData.add(new String("end"));
  behaviourData.add(new String("end-dx6"));
  NativeSelect behaviour1 = new NativeSelect("Select", behaviourData);
  behaviour1.addValueChangeListener(event -&gt; Notification.show("Value changed:",    String.valueOf(behaviour1.getValue()), Notification.Type.TRAY_NOTIFICATION));
  if (behaviour1.getValue().equals("end-dx6")) {
      System.out.print("else if");
      hop1.setVisible(true);
      out1.setVisible(true);
      nextHop.setVisible(true);
      outGoing.setVisible(true);
   }
  </code></pre>
  
  <p>But when I launch my page, I have an error because behaviour1 is empty, I understand I try to surrender by try/catch but after, when I change the value of the select it doesn't enter into my if condition. Do you have any idea?</p>