JavaFX 8.0 - How can I get a MouseEventHandle at title bar - mouseevent

Question

I have implemented a EventHandler which gets the window-drag of the mouse:
public void mouseEventHandler(){
final Delta dragDelta = new Delta();
view.getScene().setOnMousePressed(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent mouseEvent) {
dragDelta.x = mainStage.getX() - mouseEvent.getScreenX();
dragDelta.y = mainStage.getY() - mouseEvent.getScreenY();
}
});
view.getScene().setOnMouseDragged(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent mouseEvent) {
mainStage.setX(mouseEvent.getScreenX() + dragDelta.x);
mainStage.setY(mouseEvent.getScreenY() + dragDelta.y);
stage.setX(mainStage.getX());
stage.setY(mainStage.getY() + view.getScene().getHeight() + 25);
}
});
}
I have two stages: mainStage and a stage, which is addicted to the coordinates of the mainStage. My problem is, that the stage only moves if I click in the window of the mainStage and drag it. But it won't move if I click the title bar of the window for removing.
How can I get the MouseEvent for the title bar?
Here is the show() method, so you can understand the Addiction:
public void show(Stage mainStage, MenuPresenter menuPresenter){
this.model = new Model();
this.view = new GameView(this.model);
this.chatWatchView = new ChatWatchView();
this.score = this.model.getScore();
this.menuPresenter = menuPresenter;
this.mainStage = mainStage;
mainStage.setScene(view.getScene());
mainStage.centerOnScreen();
stage = new Stage();
stage.setScene(chatWatchView.getScene());
stage.initStyle(StageStyle.UNDECORATED);
stage.setX(mainStage.getX());
stage.setY(mainStage.getY() + view.getScene().getHeight() + 25);
stage.show();
mainStage.show();
startTimeline();
activateEventHandler();
mouseEventHandler();
//view.setScore("Score: " + model.getScore());
}

Answer 1

Had similar problem. Consider to add listeners to xProperty() and yProperty() of your Stage, I think it will work better.
In my case I ended up with something like this
void updatePosition(double stageX, double stageY) {
//...
}
And then
stage.xProperty().addListener(((observable, oldValue, newValue) -> {
updatePosition(newValue, stage.getY())
}));
stage.yProperty().addListener(((observable, oldValue, newValue) -> {
updatePosition(stage.getX(), newValue)
}));