FULL PRODUCT VERSION :
java version "9.0.1"
Java(TM) SE Runtime Environment (build 9.0.1+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.1+11, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 10.0.16299.125]

EXTRA RELEVANT SYSTEM CONFIGURATION :
main / first screen:
    resolution: 1920 x 1080
    scaling: 100%

second screen:
    resolution: 3840 x 2160
    scaling: 250%

A DESCRIPTION OF THE PROBLEM :
The title bar of a window has a wrong size on the second screen (too small in case of a higher resolution and too big in case of a lower resolution).

Also, the icon in the task bar on the second screen is too small in case of a higher resolution.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. run the class "TitleBarBug"
2. move the stage from the main / first screen to the second screen

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The title bar resizes and the icon in the task bar has always the right size.
ACTUAL -
The title bar is too small or too big on the second screen.
The icon in the task bar is in some cases too small on the second screen.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class TitleBarBug extends Application {

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

@Override
public void start(Stage stage) throws Exception {
Label label = new Label(
"The title bar has a wrong size on the second screen (too small in case of a higher resolution and too big in case of a lower resolution).\n\n"
+ "Also, the icon in the task bar on the second screen is too small in case of a higher resolution.");
label.setWrapText(true);
StackPane pane = new StackPane(label);
Scene scene = new Scene(pane, 600, 400);
stage.setScene(scene);
stage.setTitle("Title bar");
stage.show();
}
}
---------- END SOURCE ----------