title: JavaFX popup hidden when stage is in fullscreen mode
body: <p>I am trying to popup a dialog over my fullscreen primary stage in javafx. When I create my popup, it is unexpectedly hidden behind my fullscreen primary stage until the stage is removed from fullscreen mode (via <kbd>ESC</kbd>). If I make my primary stage maximized and undecorated instead of fullscreen, then my popup will appear on top of the primary stage as expected.</p>
  
  <p>Am I missing something about how fullscreen mode is different than maximized and undecorated mode? Am I using fullscreen mode improperly?</p>
  
  <p>I am using java version 1.8.0_20 on CentOS 6.5 with Gnome.</p>
  
  <p>Here is my SSCCE:</p>
  
  <pre><code>import javafx.application.*;
  import javafx.scene.*;
  import javafx.scene.control.*;
  import javafx.stage.*;
  
  public class TestApplication extends Application {
      private Stage primaryStage;
  
      public static void main(String[] arguments) {
          launch(arguments);
      }
  
      public void start(Stage stage) {
          this.primaryStage = stage;
  
          // Create a fullscreen primary stage.    
          primaryStage.setTitle("Main Stage");
          primaryStage.setScene(new Scene(createRoot()));
          primaryStage.setFullScreen(true);
  
          primaryStage.show();
      }       
  
      private Parent createRoot() {
          Button button = new Button("Show popup");
          button.setOnAction((event) -&gt; showPopup());
  
          return button;
      }
  
      private void showPopup() {
          // Create a popup that should be on top of the primary stage.
          Stage popupStage = new Stage();
  
          popupStage.setScene(new Scene(createPopupRoot()));
          popupStage.setTitle("Popup Stage");
          popupStage.initModality(Modality.WINDOW_MODAL);
          popupStage.initOwner(primaryStage);
  
          popupStage.show();
      }
  
      private Parent createPopupRoot() {
          return new Label("This is a popup!");
      }
  }
  </code></pre>