Blurry text appearance after some JavaFX TextArea manipulations

Question

I see a strange appearance of the text contained in a TextArea aftrer doing some changes of TextArea content and style. With the simplified code shown below I reproducibly see this when I click the button 4 times:

But this is what I expected to see:

Note: If I then click into the TextArea I see the expected result.

What can can be done to get the expected result?

Note that I need to set textarea min/max width and height to get a nice appearance of the content. Of course I could set it to a bigger value, but that would destroy the look that is required.

I tried setCache as proposed here but that did not work.

I have JavaFX-8 on Windows 8.1. I would also be interested what results are seen in newer versions.

EDIT

With JavaFX-13 the result is:

The text seems to be moved to the right instead of centered as specified in the css (and also to the bottom). I had ecpected that the text is postioned the same as on initial start of the application.

CSS:

.text-area-centered *.text {
    -fx-text-alignment: center ;
}
.text-area-centered .scroll-pane {
    -fx-hbar-policy: NEVER;
    -fx-vbar-policy: NEVER;
}

Java:

public class Main extends Application {
    private static final BackgroundFill blackBGF = new BackgroundFill(Color.BLACK, CornerRadii.EMPTY, Insets.EMPTY);
    private static final BackgroundFill whiteBGF = new BackgroundFill(Color.WHITE, CornerRadii.EMPTY, Insets.EMPTY);
    private static double textareaXY = 50; 
    private TextArea textarea = new TextArea();
    private int clickNo = 1;
    @Override
    public void start(Stage primaryStage) {

        BorderPane root = new BorderPane();
        Scene scene = new Scene(root,400,400);
        scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
        primaryStage.setScene(scene);

        VBox vb = new VBox();
        root.setCenter(vb);
        Button b = new Button("ClickMe");
        b.addEventHandler(ActionEvent.ACTION, this::OnClickButton);
        vb.getChildren().add(b);
        vb.getChildren().add(textarea);

        textarea.setEditable(false);
        textarea.getStyleClass().add("text-area-centered");
        textarea.setBackground(new Background(blackBGF));
        textarea.setMinHeight(textareaXY);
        textarea.setMaxHeight(textareaXY);
        textarea.setMinWidth(textareaXY);
        textarea.setMaxWidth(textareaXY);
        textarea.setFont(new Font("Courier New",10));

        textarea.setText("1 2 3\n4 5 6\n7 8 9");

        primaryStage.show();
    }

    private void OnClickButton(ActionEvent event)
    {
        if(clickNo == 1)
        {
            textarea.setText("7");
            textarea.setFont(new Font("Courier New Bold",24));
        }
        else if(clickNo == 2)
        {
            Region region = ( Region ) textarea.lookup( ".content" );
            region.setBackground(new Background(blackBGF));
            textarea.setStyle("-fx-text-inner-color: white;");
        }
        else if(clickNo == 3)
        {
            Region region = ( Region ) textarea.lookup( ".content" );
            region.setBackground(new Background(whiteBGF));
            textarea.setStyle("-fx-text-inner-color: black;");
        }
        else if(clickNo == 4)
        {
            textarea.setText("1 2 3\n4 5 6\n7 8 9");
            textarea.setFont(new Font("Courier New",10));
        }
        clickNo++;
    }

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