Since 8u40 there is a problem with app scaling on Retina Displays, when stage.show() is done while the initialize-method of a Component. 

Steps to reproduce:
.) Connect external display to macbook
.) Set external display as mainpanel.
.) set "parentStage.setX(0);" in FxmlComponent.java
.) Startup RetinaTest.java
.) JavaFX app should be displayed on external display and everything should be fine
.) close JavaFX app
.) set "parentStage.setX(.....);" to a value that the app will be displayed on retina display
.) wrong scaling

Also tried it with 8u31 and 8u25 => everything is fine.
Anyways this stage.show() in initialize method was a ugly hack in our app, so we won't this anymore. 





***********************************
RetinaTest.java
***********************************

package sample;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class RetinaTest extends Application {
    public static void main(String[] args) {
        launch(args);
    }
    @Override
    public void start(Stage stage) throws Exception {
        FxmlComponent root = new FxmlComponent(stage);
        stage.setScene(new Scene(root));
    }
}



***********************************
FxmlComponent.java
***********************************

package sample;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;

import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;

public class FxmlComponent extends AnchorPane implements Initializable {

    private Stage parentStage;

    @FXML
    private Label label;

    public FxmlComponent(Stage parentStage) {
        this.parentStage = parentStage;

        FXMLLoader fxmlLoader = new FXMLLoader();
        fxmlLoader.setLocation(getClass().getResource("FxmlComponent.fxml"));
        fxmlLoader.setRoot(this);
        fxmlLoader.setController(this);
        try {
            fxmlLoader.load();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @FXML
    private void handleButtonAction(ActionEvent event) {
        System.out.println("You clicked me!");
        label.setText("Hello World!");
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        
        //set X to a value, that it will be moved to retina screen
        parentStage.setX(3000);
        parentStage.setY(100);

        parentStage.setWidth(150);
        parentStage.setHeight(70);
        parentStage.show();
    }
}



***********************************
FxmlComponent.fxml
***********************************

<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<fx:root xmlns:fx="http://javafx.com/fxml"
         type="sample.FxmlComponent">
    <children>
        <Button id="button" layoutX="5" layoutY="5" text="Click Me!" onAction="#handleButtonAction" fx:id="button" />
        <Label id="label" layoutX="5" layoutY="35" minHeight="16" minWidth="70" prefHeight="16" prefWidth="70" fx:id="label" />
    </children>
</fx:root>