title: Can not catch event in the second click
body: <p>Hj. I have a combobox in Javafx. 
  Initially, I am in AVAILABLE. Then I press the combobox to choose 'AUXUALY' state, it will pop up a dialog to confirm 'AUXUALY' or not. The issue happens when I cancel the pop-up, I can not catch event click to 'AUXUALY' in the next click.</p>
  
  <p>Looking to the attached image, it seems we are still in 'AUXUALY' state because I can see a rectangle covering the 'AUXUALY' button. I can catch event only if I select the LOGOUT state.</p>
  
  <p>Is there anyone here suggest me to overcome this problem?</p>
  
  <p><a href="https://i.stack.imgur.com/jxOUn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jxOUn.png" alt="states"></a></p>
  
  <pre><code>class MyCombobox extends Combox{
  
   this.setOnAction(new EventHandler&lt;ActionEvent&gt;() {
                  @Override
                  public void handle(ActionEvent event) {  // can not catch event here after canceling the dialog 
  if change = 'AVAILABLE' then 
  if change = 'AUXUALY'  then PopUp.getinstance().showDialog();
  if change = 'LOGOUT' then 
  }
  }
  
  class PopUp extends Window{
  
  btOk.setOnAction(new EventHandler&lt;ActionEvent&gt;() {
              @Override
              public void handle(ActionEvent t) {
  ...
  }
  btCancel.setOnAction(new EventHandler&lt;ActionEvent&gt;() {
              @Override
              public void handle(ActionEvent t) {
  hide();
  }
  public void showDialog(){
  this.show();
  }
  }
  </code></pre>