ADDITIONAL SYSTEM INFORMATION :
Debian 9.6 xfce
liberica jre-11.0.9.1

A DESCRIPTION OF THE PROBLEM :
I am using the input method fcitx on linux to input Chinese. The candidate window is at the lower-left to the window. The correct behavior should be following the caret.
This also happens on Windows 10 but not on Windows 7. I solved the problem on Windows 10 by using another input method: https://pinyin.sogou.com/zhihui/

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Try to input Chinese in any input control.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
A candidate window appears near the caret
ACTUAL -
A candidate window appears below the window

---------- BEGIN SOURCE ----------
mport javafx.application.Application;
import javafx.geometry.Insets;
import javafx.stage.Stage;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import javafx.scene.layout.GridPane;


public class Test extends Application {
        @Override
        public void start(Stage primaryStage) {
                try {
                         Scene scene = new Scene(new Group(), 450, 250);

                            TextArea notification = new TextArea ();
                            notification.setText("Label");

                            notification.clear();

                            GridPane grid = new GridPane();
                            grid.setVgap(4);
                            grid.setHgap(10);
                            grid.setPadding(new Insets(5, 5, 5, 5));
                            grid.add(new Label("To: "), 0, 0);
                            grid.add(notification, 1, 0);

                            Group root = (Group) scene.getRoot();
                            root.getChildren().add(grid);
                            primaryStage.setScene(scene);
                            primaryStage.show();
                } catch(Exception e) {
                        e.printStackTrace();
                }
        }

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