Ubuntu 16.04 (Unity) + HiDPI + JDK9b122.

Please run the following sample:

import javafx.application.Application;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.ChoiceBox;
import javafx.stage.Stage;

public class ChoiceBoxApp extends Application {

    public Parent createContent() {
        ChoiceBox cb = new ChoiceBox();
        cb.getItems().addAll("One", "Two", "Three");
        cb.getSelectionModel().selectFirst();
        return cb;
    }

    @Override public void start(Stage primaryStage) throws Exception {
        primaryStage.setScene(new Scene(createContent()));
        primaryStage.show();
    }

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

the ChoiceBox is broken: can't list the items or select one of them.