ChoiceBox不会下拉

Question

我正在尝试为时区选择创建一个简单的选择框。一切似乎都工作正常，但是choicebox并未下降。

注意：我知道从未调用过某些变量（主要是大多数TimeZones）。我只打了5看看是否是间距问题。

import javafx.stage.*;
import javafx.scene.*;
import javafx.scene.layout.*;
import javafx.scene.control.*;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.TimeZone;

import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.*;

public class SetupPageTwo {

    static String name = null;

    public static void display(String title) {
        Stage window = new Stage();
        VBox layout = new VBox(10);
        Scene scene = new Scene(layout);

        ChoiceBox<String> timeSelect = new ChoiceBox<>();

        TimeZone EST = TimeZone.getTimeZone("EST");
        TimeZone HST = TimeZone.getTimeZone("HST");
        TimeZone MST = TimeZone.getTimeZone("MST");
        TimeZone ACT = TimeZone.getTimeZone("ACT");
        TimeZone AET = TimeZone.getTimeZone("AET");
        TimeZone AGT = TimeZone.getTimeZone("AGT");
        TimeZone ART = TimeZone.getTimeZone("ART");
        TimeZone AST = TimeZone.getTimeZone("AST");
        TimeZone BET = TimeZone.getTimeZone("BET");
        TimeZone BST = TimeZone.getTimeZone("BST");
        TimeZone CAT = TimeZone.getTimeZone("CAT");
        TimeZone CNT = TimeZone.getTimeZone("CNT");
        TimeZone CST = TimeZone.getTimeZone("CST");
        TimeZone CTT = TimeZone.getTimeZone("CTT");
        TimeZone EAT = TimeZone.getTimeZone("EAT");
        TimeZone ECT = TimeZone.getTimeZone("ECT");
        TimeZone IET = TimeZone.getTimeZone("IET");
        TimeZone IST = TimeZone.getTimeZone("IST");
        TimeZone JST = TimeZone.getTimeZone("JST");
        TimeZone MIT = TimeZone.getTimeZone("MIT");
        TimeZone NET = TimeZone.getTimeZone("NET");
        TimeZone NST = TimeZone.getTimeZone("NST");
        TimeZone PLT = TimeZone.getTimeZone("PLT");
        TimeZone PNT = TimeZone.getTimeZone("PNT");
        TimeZone PRT = TimeZone.getTimeZone("PRT");
        TimeZone PST = TimeZone.getTimeZone("PST");
        TimeZone SST = TimeZone.getTimeZone("SST");
        TimeZone VST = TimeZone.getTimeZone("VST");


        ObservableList<String> items = FXCollections.observableArrayList();
        timeSelect.setItems(items);
        items.addAll("EST", "HST", "MST", "ACT", "AET");
        timeSelect.show();

        timeSelect.setOnAction(e -> {

        });

        layout.getChildren().add(timeSelect);
        layout.setAlignment(Pos.CENTER);

        window.setScene(scene);
        window.showAndWait();


    }

}

我希望ChoiceBox显示所有时区变量。

谢谢！