CSS style class rendering bug

[adam at adamish.com]

(https://stackoverflow.com/questions/45440102/javafx-css-class-not-removed-when-node-disconnected)

I appeared to have discovered a case in JavaFX (8u144, running on
Windows 7) where a TextField is rendered using the wrong style class. 

This only appears to happen in the following situation

 * style class removed whilst Node not attached to Scene AND
 * parent `GridPane` has a style-class assigned, even if that class
doesn't have content.

I've separated the issue from a larger application into the following
contrived example:

    public class RenderBug extends Application {
    
        private static final String ERROR = "error";
    
        public static void main(String[] args) {
            launch(args);
        }
    
        @Override
        public void start(Stage primaryStage) throws Exception
{
            TextField field = new TextField();
            GridPane grid = new GridPane();
            grid.getStyleClass().add("some-random-class");
            grid.add(field, 0, 0);
    
            StackPane stack = new StackPane(grid);
    
            Scene scene = new Scene(stack);
            scene.getStylesheets().add("/foo.css");
            primaryStage.setWidth(300);
            primaryStage.setHeight(300);
            primaryStage.setScene(scene);
            primaryStage.show();
    
            Timeline line = new Timeline();
    
            line.getKeyFrames().add(new
KeyFrame(Duration.seconds(4), event -> {
                field.getStyleClass().add(ERROR);
            }));
            line.getKeyFrames().add(new
KeyFrame(Duration.seconds(5), event -> {
                stack.getChildren().remove(grid);
            }));
            line.getKeyFrames().add(new
KeyFrame(Duration.seconds(6), event -> {
                field.getStyleClass().remove(ERROR);
            }));
            line.getKeyFrames().add(new
KeyFrame(Duration.seconds(7), event -> {
                stack.getChildren().add(grid);
               
System.out.println(field.getStyleClass());
            }));
    
            line.play();
        }
    
    }

foo.css

    .text-field.error {
        -fx-background-color: red;
    }
    
    .some-random-class {
        /** no content required */
    }

Screenshot. At this point TextField is red, even though the class
"error" has been removed. Even interacting with the field, resizing
window etc. does not fix the issue.

[![TextField shown with red][1]][1]

Is this a genuine bug? or am I doing something wrong? I can't find any
documentation to hint that style-classes cannot or shouldn't be
updated "offline"

  [1]: https://i.stack.imgur.com/ZPEYi.png