Drag and Drop fails with JDK 7u6 in Linux

Question

Hi,
I'm face with a strange bug on JavaFX 2.2 (JDK 7u6, Ubuntu 12); I implemented drag & drop feature of labels in a stage; first time, I open the stage, the drag & drop works well; when I close the stage and reopen it, it fails : I can drag the label but I cannot drop it on the target (the target events are not fired); I can reproduce the bug easily with the class below, you have just to instantiate the class TestDragAndDrop in an application class.
On window 7, it works well, I cannot reproduce the bug.
Thank you for your help,
David
public class TestDragAndDrop {
    public TestDragAndDrop() {
        Stage stage = new Stage();
        stage.setTitle("Hello Drag And Drop");
        Group root = new Group();
        Scene scene = new Scene(root, 400, 200);
        scene.setFill(Color.LIGHTGREEN);
        final Text source = new Text(50, 100, "DRAG ME");
        source.setScaleX(2.0);
        source.setScaleY(2.0);
        final Text target = new Text(250, 100, "DROP HERE");
        target.setScaleX(2.0);
        target.setScaleY(2.0);
        source.setOnDragDetected(new EventHandler <MouseEvent>() {
            public void handle(MouseEvent event) {
                /* drag was detected, start drag-and-drop gesture*/
                System.out.println("onDragDetected");
                /* allow any transfer mode */
                Dragboard db = source.startDragAndDrop(TransferMode.ANY);
                /* put a string on dragboard */
                ClipboardContent content = new ClipboardContent();
                content.putString(source.getText());
                db.setContent(content);
                event.consume();
        target.setOnDragOver(new EventHandler <DragEvent>() {
            public void handle(DragEvent event) {
                /* data is dragged over the target */
                System.out.println("onDragOver");
                /* accept it only if it is  not dragged from the same node
                 * and if it has a string data */
                if (event.getGestureSource() != target &&
                        event.getDragboard().hasString()) {
                    /* allow for both copying and moving, whatever user chooses */
                    event.acceptTransferModes(TransferMode.COPY_OR_MOVE);
                event.consume();
        target.setOnDragEntered(new EventHandler <DragEvent>() {
            public void handle(DragEvent event) {
                /* the drag-and-drop gesture entered the target */
                System.out.println("onDragEntered");
                /* show to the user that it is an actual gesture target */
                if (event.getGestureSource() != target &&
                        event.getDragboard().hasString()) {
                    target.setFill(Color.GREEN);
                event.consume();
        target.setOnDragExited(new EventHandler <DragEvent>() {
            public void handle(DragEvent event) {
                /* mouse moved away, remove the graphical cues */
                target.setFill(Color.BLACK);
                event.consume();
        target.setOnDragDropped(new EventHandler <DragEvent>() {
            public void handle(DragEvent event) {
                /* data dropped */
                System.out.println("onDragDropped");
                /* if there is a string data on dragboard, read it and use it */
                Dragboard db = event.getDragboard();
                boolean success = false;
                if (db.hasString()) {
                    target.setText(db.getString());
                    success = true;
                /* let the source know whether the string was successfully
                 * transferred and used */
                event.setDropCompleted(success);
                event.consume();
        source.setOnDragDone(new EventHandler <DragEvent>() {
            public void handle(DragEvent event) {
                /* the drag-and-drop gesture ended */
                System.out.println("onDragDone");
                /* if the data was successfully moved, clear it */
                if (event.getTransferMode() == TransferMode.MOVE) {
                    source.setText("");
                event.consume();
        root.getChildren().add(source);
        root.getChildren().add(target);
        stage.setScene(scene);
        stage.show();
    public static void main(String[] args) {
        Application.launch(args);

Answer 1

DUUUUUUUDE! IT'S WORKING NOW!!!!
When you originally asked, "What happens if you click on an image and move it to another folder?", I didn't really understand what you were talking about because I almost never have my workspace set up in a way that the folders are showing. I always hide them. So I didn't really understand what you were saying. Just a few minutes ago, I realized that that is what you were asking so I opened up the folder area and tried dragging thumbs into different folders and saw that it does work.
So then, because of you mentioning that blue line and me know that I did see the blue line on occasion. I went back over into the thumbnails to find out if I always got the blue line or if it was a hit or miss thing. I couldn't believe my eyes when all of the sudden I saw that I no longer was getting that circle with the line through it, and low and behold, the thumbnail dropped right into position like it is supposed to!!!!
The thing is, I don't know what I've learned from this. I thought, "well, what is different?" The only thing that I can think of is that I now have the folders showing in my workspace so I wondered if that was the secret but I just now hid the folders again like I usually do and the drag and drop into position is STILL WORKING!!!
All I can figure is that somehow, dragging and dropping a thumbnail into a folder like that for the first time, triggered something so that I can now drag and drop among the thumbnail positions? Not sure. All I know is that for some reason, IT'S WORKING NOW!
Now, for the second important part, I wonder if I drag and drop everything into the order that I want and then select all of the files and drag them into a new folder, will they stay in that order? I need to go experiment with that.
If you hadn't kept at it and in turn had me keep trying stuff, it would have never happened because I had pretty much given up.
Thanks Curt!
You da man!!!