ADDITIONAL SYSTEM INFORMATION :
Ubuntu 24.04
jdk-21.0.5+11
javafx-sdk-21.0.5


A DESCRIPTION OF THE PROBLEM :
I am experiencing issues when porting a JavaFX application from version 17 to 21. Specifically, I'm having trouble setting the location of a Stage. While javaJDK/javaFX versions 11 and 17 work correctly for me, version 21.0.5 on Ubuntu 24.04 (which also works fine on Windows 11) sets the window to location (0,0) in 8 out of 10 times.

REGRESSION : Last worked in version 17.0.13

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Reproduce by running the following:

import javafx.application.Application;
//import javafx.stage.Modality;
import javafx.stage.Stage;

public class App extends Application {
    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) {
          Stage stage = new Stage();
        //stage.initModality(Modality.APPLICATION_MODAL);
        //stage.initModality(Modality.WINDOW_MODAL);
        //stage.initModality(Modality.NONE);
        stage.initOwner(primaryStage);
        stage.setTitle("Test App");

        stage.setX(500);
        stage.setY(500);
        stage.setWidth(200);
        stage.setHeight(100);

        stage.showAndWait();
    }
}


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Window set at location (500,500)
ACTUAL -
Window set at location (0,0)

CUSTOMER SUBMITTED WORKAROUND :
None found yet

FREQUENCY : always