C# 两个API函数.[关于插入光标]

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices; //调用API,需要引用这个命名空间

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {


        /// <summary>
        /// 两个API函数,其作用是:指定窗口的指定位置插入插入符.
        /// </summary>
        /// <param name="hwnd">窗口句柄</param>
        /// <param name="hBitmap">插入符的样式,可以为NULL</param>
        /// <param name="nWidth">插入符的宽度</param>
        /// <param name="nHeight">插入符的高度</param>
        /// <returns></returns>

        [DllImport("user32.dll", EntryPoint = "CreateCaret")]
        static extern int CreateCaret(IntPtr hwnd, int hBitmap, int nWidth, int nHeight);

        /// <summary>
        /// 显示插入符
        /// </summary>
        /// <param name="hWnd">窗口句柄</param>
        /// <returns></returns>
        [DllImport("user32.dll", EntryPoint = "ShowCaret")]
        static extern bool ShowCaret(IntPtr hWnd);       
        
        
        public Form1()
        {
            InitializeComponent();
        }


        private void button2_Click(object sender, EventArgs e)
        {
            CreateCaret(this.Handle, 1, 20, 40);
            ShowCaret(this.Handle);
            
        }


    }


    

}