In an app that I am working on, running on a dual monitor setup, I notice that the main window can switch from one screen to the other when minimized and maximized (at least on Windows 7). I reduced this to the following minimal test case (read the comments in the code for instructions):

import javafx.application.Application;
import javafx.collections.ObservableList;
import javafx.geometry.Rectangle2D;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.stage.Screen;
import javafx.stage.Stage;

/**
 * This is a minimal test app for an issue I am seeing in a much larger application that I am working on
 * related to a dual monitor setup.
 *
 * This program reproduces an issue for me on Windows 7, and JDK 8u40 b09. Run the program and the app window
 * should be maximised on the *secondary* screen. Click the icon in the Windows taskbar to minimise the app,
 * then click again to maximise. The app is now maximised but has switched to the primary screen.
 *
 * Note the line stage.setMaximized(true) - if you comment this out, the issue goes away.
 */
public class DualMonitorTest extends Application {
   
    public static void main(String[] args) {
        launch(args);
    }
 
    @Override
    public void start(Stage stage) {
        stage.setTitle("Dual Monitor Test");
        stage.setResizable(true);
        stage.setMaximized(true); // comment out this line and there is no issue

        BorderPane bp = new BorderPane();
        bp.setCenter(new Button("Imagine that clicking this button gives pay increases to the JavaFX team ... in fact, it does nothing."));
        Scene scene = new Scene(bp);
        stage.setScene(scene);
        stage.show();
        ObservableList<Screen> screens = Screen.getScreens();
        Rectangle2D bounds = screens.get(1).getVisualBounds();
        stage.setX(bounds.getMinX());
        stage.setY(bounds.getMinY());
        stage.setWidth(bounds.getWidth());
        stage.setHeight(bounds.getHeight());
    }

}