Interoperability problems when using JavaFx combobox within SWT Dialog - interop

Question

JavaFx is supposed to be easily integrated in an SWT application (see here: http://docs.oracle.com/javafx/2/swt_interoperability/jfxpub-swt_interoperability.htm) and both toolkits use the same threading model.
However things get strange, when I open a dialog containing an FxCanvas which contains a JavaFx ComboBox. If I open the combo box popup menu and then close the dialog, the popup menu stays open. If I now move the mouse onto the popup a null pointer exception is thrown within javafx. When doing this within a larger application all JavaFx GUIs remain broken until the application is restarted.
Any ways to work around this?
Example code below: Close the dialog with 'Ok' or the window close button. Exit the application with 'Cancel'
package test;
import javafx.embed.swt.FXCanvas;
import javafx.geometry.Insets;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.ComboBox;
import javafx.scene.layout.StackPane;
import org.eclipse.jface.dialogs.Dialog;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
public class TestFx {
static class MyDialog extends Dialog {
Parent w;
public MyDialog(Shell parent,Parent n) {
super(parent);
this.w = n;
setShellStyle(SWT.RESIZE| SWT.BORDER | SWT.TITLE |SWT.CLOSE );
}
#Override
public void cancelPressed() {
System.exit(0);
}
#Override
protected Control createDialogArea(Composite parent) {
Composite container = (Composite) super.createDialogArea(parent);
container.setLayout(new FillLayout());
FXCanvas fxCanvas = new FXCanvas(container, SWT.NONE);
Scene scene = new Scene(w);
fxCanvas.setScene(scene);
return container;
}
}
private static Parent createScene() {
StackPane pane = new StackPane();
pane.setPadding(new Insets(10));
ComboBox<String> c = new ComboBox<String>();
c.getItems().addAll("Test1","Test2");
pane.getChildren().add(c);
return pane;
}
public static void main(String[] args) {
Display display = new Display();
Shell shell = new Shell(display);
while (true) {
MyDialog d = new MyDialog(shell,createScene());
d.open();
}
}
}
Exception:
java.lang.NullPointerException
at com.sun.javafx.tk.quantum.GlassScene.sceneChanged(GlassScene.java:290)
at com.sun.javafx.tk.quantum.ViewScene.sceneChanged(ViewScene.java:156)
at com.sun.javafx.tk.quantum.PopupScene.sceneChanged(PopupScene.java:30)
at com.sun.javafx.tk.quantum.GlassScene.markDirty(GlassScene.java:157)
at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2214)
at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:363)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:460)
at com.sun.javafx.tk.quantum.QuantumToolkit$9.run(QuantumToolkit.java:329)
at org.eclipse.swt.internal.win32.OS.DispatchMessageW(Native Method)
at org.eclipse.swt.internal.win32.OS.DispatchMessage(OS.java:2546)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3756)
at org.eclipse.jface.window.Window.runEventLoop(Window.java:825)
at org.eclipse.jface.window.Window.open(Window.java:801)
at test.TestFx.main(TestFx.java:55)

Answer 1

At work we're developing some applications using JavaFX, on top of and old Swing platform and we also have found this issue.
Apparently it is caused by some issues on JFXPanel which is not correctly propagating some window events (focus, iconifying, etc) to the FX framework. The issue affects not only the ComboBox component, but every component that uses a PopupWindow (Menu, Tooltip, etc), specially when using Swing's JInternalFrame.
So, when a Popup is displaying and the window is minimized or closed, the Popup does not hide, causing the FX thread to crash if you try subsequently to interact with it.
The workaround mentioned above works, but only for ComboBox, as Menu and Tooltip does not inherit from the Node class, so didn't work for us :(
I developed another workaround which resolved the problem for all components that display popups, which basically forces all popups to close whenever a JFXPanel loses focus:
private static void initFX(final JFXPanel jfxPanel) {
final TestFxPanel parent = new TestFxPanel();
final Scene scene = new Scene(parent);
jfxPanel.setScene(scene);
jfxPanel.addFocusListener(new FocusAdapter() {
#Override
public void focusLost(final FocusEvent e) {
System.out.println(jfxPanel.getName() + ": FocusLost");
runFocusPatch(scene);
}
});
}
static void runFocusPatch(final Scene scene) {
Platform.runLater(new Runnable() {
#Override
public void run() {
System.out.println("Running patch");
final Iterator<Window> winIter = scene.getWindow().impl_getWindows();
while (winIter.hasNext()) {
final Window t = winIter.next();
if (t instanceof PopupWindow) {
System.out.println("Got a popup");
Platform.runLater(new Runnable() {
#Override
public void run() {
((PopupWindow) t).hide();
}
});
}
}
}
});
}
I confirm that the issue is NOT present in 8.0. Sadly we are not allowed to java 8 in production software as its still in beta stage.
best regards.

Answer 2

I found a workaround when using Java7: Override the close method in Dialog to hide the combo box popups:
#Override
public boolean close() {
Set<Node> nodes = w.lookupAll("#");
for (Node n : nodes)
if (n instanceof ComboBox)
((ComboBox)n).hide();
return super.close();
}

Answer 3

The trouble is discussed here : javafx-jira.kenai.com/browse/RT-30991
Developer has said, that the issue is fixed in JavaFX-8