Fix for javafx clipboard issue.

package sample;

import com.sun.glass.ui.ClipboardAssistance;
import javafx.application.Application;
import javafx.embed.swing.SwingFXUtils;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.ColorPicker;
import javafx.scene.control.Label;
import javafx.scene.effect.BlendMode;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.Clipboard;
import javafx.scene.layout.*;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

import java.awt.*;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.IOException;

/**
 * A program to test out the differences between the AWT Java Clipboard and the JavaFX Clipboard.
 * <p>
 * Based on the code by crusam: https://stackoverflow.com/q/48932575/5432315
 */
public class ClipBoardFxAwtComparison extends Application {

    @Override
    public void start(final Stage primaryStage) {
        final BorderPane root = new BorderPane();
        final Group group = new Group();

        final Button awtButton = new Button("AWT");
        awtButton.setOnAction(event -> loadImageFromAWTClipboard(group));

        final Button javaFXButton = new Button("JavaFX");
        javaFXButton.setOnAction(event -> loadImageFromJavaFXClipboard(group));

        root.setCenter(group);

        final BorderPane buttonPane = new BorderPane();
        buttonPane.setLeft(awtButton);
        buttonPane.setCenter(new Label("Copy and image then click a button to paste it."));
        buttonPane.setRight(javaFXButton);
        root.setBottom(buttonPane);

        final ColorPicker colorPicker = new ColorPicker();
        colorPicker.setOnAction(event -> {
            root.setBackground(
                    new Background(
                            new BackgroundFill(
                                    colorPicker.getValue(),
                                    CornerRadii.EMPTY,
                                    Insets.EMPTY)
                    )
            );
        });

        BorderPane.setAlignment(colorPicker, Pos.CENTER);
        root.setTop(colorPicker);

        final Scene scene = new Scene(root, 400, 400);
        primaryStage.setScene(scene);
        primaryStage.show();

        listenToClipboard();
    }

    /**
     * This little bit of magic comes courtesy of Александр Савостьянов: https://stackoverflow.com/a/47550034/5432315
     */
    private void listenToClipboard() {
        Clipboard clipboard = Clipboard.getSystemClipboard();
        new ClipboardAssistance(com.sun.glass.ui.Clipboard.SYSTEM) {
            @Override
            public void contentChanged() {
                System.out.println("System clipboard content changed.");
                System.out.println("Clipboard content types: ");
                clipboard.getContentTypes().forEach(System.out::println);
                System.out.println();
            }
        };
    }

    private void loadImageFromAWTClipboard(final Group group) {
        System.out.println("Adding an image from the JavaFX Clipboard...");
        final Clipboard clipboard = Clipboard.getSystemClipboard();

        try {
            final Transferable t = Toolkit.getDefaultToolkit().getSystemClipboard().getContents(null);

            if (t != null && t.isDataFlavorSupported(DataFlavor.imageFlavor)) {
                final java.awt.image.BufferedImage img = (java.awt.image.BufferedImage) t.getTransferData(DataFlavor.imageFlavor);

                final Image image = SwingFXUtils.toFXImage(img, null);

                setupImageFixingGroup(group, image);
            } else {
                new Alert(Alert.AlertType.INFORMATION, "No image detected on the Clipboard!").show();
                group.getChildren().clear();
            }
        } catch (final UnsupportedFlavorException | IOException e) {
            e.printStackTrace();
        }
    }

    private void loadImageFromJavaFXClipboard(final Group group) {
        System.out.println("Adding an image from the JavaFX Clipboard...");
        final Clipboard clipboard = Clipboard.getSystemClipboard();

        if (clipboard.hasImage()) {
            final Image image = clipboard.getImage();

            setupImageFixingGroup(group, image);
        } else {
            new Alert(Alert.AlertType.INFORMATION, "No image detected on the Clipboard!").show();
            group.getChildren().clear();
        }
    }

    private void setupImageFixingGroup(Group group, Image image) {
        final ImageView view = new ImageView(image);
        view.setBlendMode(BlendMode.LIGHTEN);

        final Rectangle blend = new Rectangle(image.getWidth(), image.getHeight(), Color.BLACK);
        blend.widthProperty().bind(image.widthProperty());
        blend.heightProperty().bind(image.heightProperty());

        group.getChildren().clear();
        group.getChildren().addAll(blend, view);
    }

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