How can I add a swingNode to a specific pane?
I'm actually trying to add a JPanel that loads an applet to the transparent area of the following and I'm not sure how to do it.

SwingNode is a javafx scene node and can be added to any javafx scene layouts.
To add a JPanel to a Pane and display it on JavaFX stage:
A very simple code sample to show how you can add it to a Pane is (from SwingNode Javadoc):
public class SwingNodeExample extends Application {
     @Override
     public void start(Stage stage) {
         final SwingNode swingNode = new SwingNode();
         createAndSetSwingContent(swingNode);
         Pane pane = new Pane();
         pane.getChildren().add(swingNode); // Adding swing node
         stage.setScene(new Scene(pane, 100, 50));
         stage.show();
     }
     private void createAndSetSwingContent(final SwingNode swingNode) {
         SwingUtilities.invokeLater(new Runnable() {
             @Override
             public void run() {
                 JPanel panel = new JPanel();
                 panel.add(new JButton("Click me!"));
                 swingNode.setContent(panel);
             }
         });
     }
     public static void main(String[] args) {
         launch(args);
     }
 }