C# 点击窗口任意位置拖动

代码：

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Runtime.InteropServices;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows.Forms;

 namespace FreeNotes
 {
     public partial class kk : Form
     {
         public kk()
         {
             InitializeComponent();
         }

         [DllImport("user32.dll")]
         public static extern bool ReleaseCapture();

         [DllImport("user32.dll")]
         public static extern bool SendMessage(IntPtr hwnd, int wMsg, int wParam, int lParam);

         private void kk_MouseDown(object sender, MouseEventArgs e)
         {
             ReleaseCapture();
             SendMessage(this.Handle, 0x0112, 0xF012, );
         }
     }
 }