ADDITIONAL SYSTEM INFORMATION :
KDE Plasma 6.3.4
Manjaro Linux
JDK 24.0.1

A DESCRIPTION OF THE PROBLEM :
When there are two stages, each holding a SwingNode with a JTextField, and the unfocused on is selected, then neither one is able to keep focus for more than a fraction of a second.
This was also tested with JavaFX SDK 25-ea+11 instead of 24.0.1. It was the same result.

The focus listeners in the test case code is used to request focus when lost, but it doesn't help.

This issue happens always when running on Linux, however on Windows focus works as expected.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Set two Stages, each with its own Scene.
Add SwingNodes, one to each Scene.
Add JTextFields, one to each SwingNode.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
After clicking on a JTextField that isn't focused, a caret appears there and the text can be manipulated using keys and/or mouse.
ACTUAL -
After clicking on a JTextField that isn't focused, a caret blinks for a split second before disappearing and the JTextField is completely unresponsive to key/mouse input.
Clicking on the same JTextField or the other one results in the same again.

---------- BEGIN SOURCE ----------
package com.ergotech;

import javafx.application.Platform;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;
import javafx.application.Application;
import javafx.embed.swing.SwingNode;

import javax.swing.*;
import java.awt.*;
import java.awt.event.FocusListener;

public class WindowDemo extends Application {

    private Pane scenePane1, scenePane2;

    @Override
    public void start(Stage stage1) throws InterruptedException {
        scenePane1 = new Pane();
        scenePane2 = new Pane();

        Scene scene1 = new Scene(scenePane1, 200, 100);
        Scene scene2 = new Scene(scenePane2, 200, 100);

        Stage stage2 = new Stage();
        stage1.setScene(scene1);
        stage2.setScene(scene2);

        stage1.show();
        stage2.show();

        JTextField jTextField1 = new JTextField("JTextField 1");
        jTextField1.setName("JTextField 1");
        JTextField jTextField2 = new JTextField("JTextField 2");
        jTextField2.setName("JTextField 2");

        FocusListener focusListener = new FocusListener() {
            @Override
            public void focusGained(java.awt.event.FocusEvent e) {
                System.out.println("Focus gained: " + e.getComponent().getName());
            }

            @Override
            public void focusLost(java.awt.event.FocusEvent e) {
                System.out.println("Focus lost: " + e.getComponent().getName()
                        + ", new focus owner: " + KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner());
            }
        };

        jTextField1.addFocusListener(focusListener);
        jTextField2.addFocusListener(focusListener);

        SwingNode swingNode1 = new SwingNode();
        swingNode1.setId("swingNode1");
        SwingNode swingNode2 = new SwingNode();
        swingNode2.setId("swingNode2");

        Platform.runLater(() -> {
            scenePane1.getChildren().add(swingNode1);
            scenePane1.requestFocus();
            scenePane2.getChildren().add(swingNode2);
            scenePane2.requestFocus();
        });

        swingNode2.setTranslateY(50);

        SwingUtilities.invokeLater(() -> {
            swingNode1.setContent(jTextField1);
            swingNode2.setContent(jTextField2);
        });

        Platform.runLater(swingNode2::requestFocus);
        Platform.runLater(() -> {
            System.out.println("FX scene 1 focus owner: " + scenePane1.getScene().focusOwnerProperty().get().getId());
            System.out.println("FX scene 2 focus owner: " + scenePane2.getScene().focusOwnerProperty().get().getId());
        });

        Platform.runLater(swingNode1::requestFocus);
        Platform.runLater(() -> {
            System.out.println("FX scene 1 focus owner: " + scenePane1.getScene().focusOwnerProperty().get().getId());
            System.out.println("FX scene 2 focus owner: " + scenePane2.getScene().focusOwnerProperty().get().getId());
        });
    }

    public static void main(String[] args) {
        launch();
    }
}
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