c#单击按钮时如何打开组合框

using System;
using System.Windows.Forms;

public class MainForm : Form
{
    private ComboBox comboBox;
    private Button button;

    public MainForm()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        this.comboBox = new ComboBox();
        this.button = new Button();

        // 初始化ComboBox
        this.comboBox.DropDownStyle = ComboBoxStyle.DropDownList;
        this.comboBox.Items.Add("Option 1");
        this.comboBox.Items.Add("Option 2");
        this.comboBox.Items.Add("Option 3");

        // 初始化按钮
        this.button.Text = "Toggle ComboBox";
        this.button.Click += new EventHandler(this.button_Click);

        // 设置布局
        this.SuspendLayout();
        this.comboBox.Location = new System.Drawing.Point(50, 50);
        this.button.Location = new System.Drawing.Point(50, 100);
        this.ClientSize = new System.Drawing.Size(200, 200);
        this.Controls.Add(this.comboBox);
        this.Controls.Add(this.button);
        this.ResumeLayout(false);
    }

    private void button_Click(object sender, EventArgs e)
    {
        // 切换ComboBox的展开状态
        this.comboBox.DroppedDown = !this.comboBox.DroppedDown;
    }

    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new MainForm());
    }
}