ADDITIONAL SYSTEM INFORMATION :
Win8.1, JDK12, JavaFX 16ea+1

A DESCRIPTION OF THE PROBLEM :
This issue has always existed as far as I know and exists on the latest JavaFX 16ea+1.
 
Because the private method `javafx.stage.Screen.updateConfiguration`
uses
```
            Screen.screens.clear();
            Screen.screens.addAll(newScreens);
```
instead of
```
            Screen.screens.setAll(newScreens);
```
changes in the list produce 2 change events, resulting in an invalid intermediate state (empty list after `clear()`). Even worse, list of screens can be empty, provided there is no screen available.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Plug/unplug screen from the system

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Single list change when screen is pluged/unplugged.
ACTUAL -
Multiple list changes when screen is plugged/unplugged.

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.collections.ListChangeListener.Change;
import javafx.scene.Scene;
import javafx.scene.layout.StackPane;
import javafx.stage.Screen;
import javafx.stage.Stage;

class ScreenEvents extends Application {

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

@Override
public void start(Stage stage) {

Screen.getScreens().addListener((Change<?> event) -> {
System.out.println("");
                        System.out.println(Screen.getPrimary());
System.out.println(Screen.getScreens().size());
});

final StackPane background = new StackPane(); final Scene scene = new Scene(background, 600, 500);
stage.show();
}

}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Ignore every second list change event

FREQUENCY : always