The following app hangs when launched on MacOS X with jdk8u40 as a jnlp app (netbeans project is attached):

package cft;

import javafx.application.Platform;
import javafx.embed.swing.JFXPanel;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class CFT {
         private static void initAndShowGUI() {
             JFrame frame = new JFrame("FX");
             frame.setSize(100, 100);
             final JFXPanel fxPanel = new JFXPanel();
             frame.add(fxPanel);
             frame.setVisible(true);

             Platform.runLater(new Runnable() {
                 @Override
                 public void run() {
                     initFX(fxPanel);
                 }
             });
         }

         private static void initFX(JFXPanel fxPanel) {
             Scene scene = createScene();
             fxPanel.setScene(scene);
         }

         private static Scene createScene() {
             StackPane p = new StackPane();
 	     Scene scene = new Scene(p);
             p.getChildren().add(new Button("fx button"));
             return scene;
	 }

         public static void main(String[] args) {
             SwingUtilities.invokeLater(new Runnable() {
                 @Override
                 public void run() {
                     initAndShowGUI();
                 }
             });
         }
}