JavaFX misreports my screen sizes on Linux. Is this a bug?

Question

The following code uses java.awt.GraphicsDevice and javafx.stage.Screen to get the screen sizes in pixels. JavaFX seems to get it wrong under Linux, as shown below (but correct under Windows 7). I would be interested to know if anyone else has experienced the same apparent bug.

import javafx.application.Application;
import javafx.stage.*;
import java.awt.*;

public class DisplayCheck extends Application {

    static int getScreenWidthViaAWT(int screenNum) {
        GraphicsDevice gd = GraphicsEnvironment.getLocalGraphicsEnvironment().getScreenDevices()[screenNum];
        return gd.getDisplayMode().getWidth();
    }

    static int getScreenHeightViaAWT(int screenNum) {
        GraphicsDevice gd = GraphicsEnvironment.getLocalGraphicsEnvironment().getScreenDevices()[screenNum];
        return gd.getDisplayMode().getHeight();
    }

    static int getScreenWidthViaJavaFX(int screenNum) {
        return (int)Screen.getScreens().get(screenNum).getVisualBounds().getWidth();
    }

    static int getScreenHeightViaJavaFX(int screenNum) {
        return (int)Screen.getScreens().get(screenNum).getVisualBounds().getHeight();
    }

    public static void main(String[] args) {

        int w0 = getScreenWidthViaAWT(0);
        int h0 = getScreenHeightViaAWT(0);
        int w1 = getScreenWidthViaAWT(1);
        int h1 = getScreenHeightViaAWT(1);

        System.out.println ("\n\nScreen sizes from java.awt.GraphicsDevice:\n\nScreen 0: " + w0 + " x " + h0 + "\nScreen 1: " + w1 + " x " + h1);

        w0 = getScreenWidthViaJavaFX(0);
        h0 = getScreenHeightViaJavaFX(0);
        w1 = getScreenWidthViaJavaFX(1);
        h1 = getScreenHeightViaJavaFX(1);

        System.out.println ("\n\nScreen sizes from javafx.stage.Screen:\n\nScreen 0: " + w0 + " x " + h0 + "\nScreen 1: " + w1 + " x " + h1);

        launch(args);
    }

    public void start (Stage stage) {
        System.exit(0);     
    }
 } 

On my system (Ubuntu MATE), JavaFX misreports the heights of both my laptop screen and my external monitor as 718 pixels. AWT gets it right. The results are as follows:

john@jlaptop2:/java$ javac DisplayCheck.java
john@jlaptop2:/java$ java DisplayCheck


Screen sizes from java.awt.GraphicsDevice:

Screen 0: 1024 x 768
Screen 1: 1920 x 1080


Screen sizes from javafx.stage.Screen:

Screen 0: 1920 x 718
Screen 1: 1024 x 718
john@jlaptop2:/java$

Answer 1

You are using Screen.getVisualBounds instead of Screen.getBounds. The visual bounds exclude the area occupied by task bars, ect.

From the javadoc of Screen.getVisualBounds:

These bounds account for objects in the native windowing system such as task bars and menu bars.