Stages sometimes appear at four times the expected resolution when using retina screens. The issue occurs when a stage is shown on a retina screen while a non-retina screen is in focus.

Reproduction steps:

1) Set the retina screen as the primary screen and connect an external (non-retina) monitor
2) Run the sample code below from an IDE or console that's located on the external (non-retina) monitor.

Result: The button will show at four times the expected size (but the size of the stage is correct).

public class TestRetina extends Application {

@Override
public void start(Stage primaryStage) throws Exception {
Button button = new Button("This is a test");

StackPane stackPane = new StackPane(button);

Scene scene = new Scene(stackPane);

primaryStage.setScene(scene);

primaryStage.show();
}

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