ComboSample

ComboSample.java

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.concurrent.Task;
import javafx.scene.Cursor;
import javafx.scene.Scene;
import javafx.scene.control.ComboBox;
import javafx.scene.control.Label;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * Steps to reproduce issues:
 * 1. Select "DEV" from first dropdown - it will run for 20s
 * 2. Immediately select "TEST" from 2nd dropdown - it will run for 5s
 *
 * Expected result
 * 1. Cursor remains WAIT until both tasks have completed
 * 2. When both tasks have completed Cursor should remain at DEFAULT
 *    when placed over 2nd comboxbox drop down
 *
 * Actual result
 * 1. Cursor changes to DEFAULT before 1st task has completed
 * 2. (Intermittent): After both tasks have completed, clicking on 2nd combo
 *    and placing mouse pointer over dropdown list, causes cursor to change
 *    back to WAIT.
 */
public class ComboSample extends Application {
    public static void main(String[] args) { launch(args); }

    private final ExecutorService pool = Executors.newFixedThreadPool(4);
    final ObjectProperty<Cursor> CURSOR_DEFAULT = new SimpleObjectProperty<>(Cursor.DEFAULT);
    final ObjectProperty<Cursor> CURSOR_WAIT = new SimpleObjectProperty<>(Cursor.WAIT);

    @Override public void start(final Stage primaryStage) {
        primaryStage.setTitle("Combo Sample");
        Label label1 = new Label();
        Label label2 = new Label();

        ComboBox<String> from = new ComboBox<>();
        from.getItems().addAll("DEV", "TEST", "PROD");
        from.getSelectionModel().selectedItemProperty().addListener((observable, oldValue, newValue) -> {
            pool.submit(task1);
            label1.textProperty().bind(task1.messageProperty());
        });

        ComboBox<String> to = new ComboBox<>();
        to.getItems().addAll("DEV", "TEST", "PROD");
        to.getSelectionModel().selectedItemProperty().addListener((observable, oldValue, newValue) -> {
            pool.submit(task2);
            label2.textProperty().bind(task2.messageProperty());
        });

        HBox layout = new HBox(10);
        layout.getChildren().addAll(new VBox(from, label1), new VBox(to, label2));
        primaryStage.setScene(new Scene(layout));
        primaryStage.setWidth(400);
        primaryStage.setHeight(200);
        primaryStage.show();
        primaryStage.getScene().cursorProperty().bind(Bindings.when(Bindings.or(task1.runningProperty(), task2.runningProperty()))
                .then(CURSOR_WAIT).otherwise(CURSOR_DEFAULT));

        primaryStage.setOnCloseRequest(event -> {
            pool.shutdownNow();
        });
    }

    Task<Void> task1 = new Task<Void>() {
        @Override protected Void call() throws Exception {
            System.out.println("selectFrom - Start");
            for(int i=1; i<=20; i++) {
                updateMessage(String.valueOf(i));
                Thread.sleep(1000);
            }
            System.out.println("selectFrom - End");
            return null;
        }
    };

    Task<Void> task2 = new Task<Void>() {
        @Override
        protected Void call() throws Exception {
            System.out.println("selectTo - Start");
            for(int i=1; i<=5; i++) {
                updateMessage(String.valueOf(i));
                Thread.sleep(1000);
            }
            System.out.println("selectTo - End");
            return null;
        }
    };
}

Thanks for this. Note as Task is a one-shot class the selection event wont run a 2nd time - also is it possible to bind dynamically if we don't define all the tasks up front? I'm looking for a solution where I can pass any task through this Cursor.WAIT pattern.