title: Update validator
body: <p>I'm using this code to validate TextField for network port.</p>
  
  <pre><code>fieldNport.textProperty().addListener(new ChangeListener&lt;String&gt;()
  {
      @Override
      public void changed(ObservableValue&lt;? extends String&gt; observable, String oldValue, String newValue)
      {
          IpAddressNameValidator.hide();
          if (!newValue.matches("-?\\d+(\\.\\d+)?"))
          {
              MenuItem cc = new MenuItem(newValue + " is not correct network port");
              cc.getStyleClass().add("validator-item");
              IpAddressNameValidator.getItems().clear();
              IpAddressNameValidator.getItems().add(cc);
              IpAddressNameValidator.show(fieldNport, Side.RIGHT, 10, 0);
          }
      }
  });
  </code></pre>
  
  <p>I noticed that the validator is not updated when I delete the old value with backspace. The only solution that I found is this IpAddressNameValidator.hide(); and then show the validator message again.</p>
  
  <p>I there other way to refresh the validator message when I add or remove values? This solution works but the message is blinking when I add new values.</p>