一、

在最前面：
using System.Runtime.InteropServices;
在定义部分引入下面两个函数：
[DllImport( "user32 ")]
private static extern IntPtr FindWindow(string lpClassName,string lpWindowName);
[DllImport( "user32 ")]
private static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
在窗体On_Load事件中添加（Santos的代码）：
IntPtr hDeskTop=FindWindow( "Progman ", "Program Manager ");
SetParent(this.Handle,hDeskTop);
另一个方法可以修改桌面壁纸实现
经测试，win2000--win2003 、xp下嵌入桌面，不支持vista和win7以上系统

二、

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; namespace ShowInDesk { publicpartialclass Form1 : Form { IntPtr hDesktop; publicconstint GW_CHILD =5; public Form1() { InitializeComponent(); this.hDesktop = GetDesktopHandle(DesktopLayer.Progman); EmbedDesktop(this, this.Handle, this.hDesktop); isMouseDown =false; } public IntPtr GetDesktopHandle(DesktopLayer layer) { //hWnd = new HandleRef(); HandleRef hWnd; IntPtr hDesktop =new IntPtr(); switch (layer) { case DesktopLayer.Progman: hDesktop = Win32Support.FindWindow("Progman", null);//第一层桌面 break; case DesktopLayer.SHELLDLL: hDesktop = Win32Support.FindWindow("Progman", null);//第一层桌面 hWnd =new HandleRef(this, hDesktop); hDesktop = Win32Support.GetWindow(hWnd, GW_CHILD);//第2层桌面 break; case DesktopLayer.FolderView: hDesktop = Win32Support.FindWindow("Progman", null);//第一层桌面 hWnd =new HandleRef(this, hDesktop); hDesktop = Win32Support.GetWindow(hWnd, GW_CHILD);//第2层桌面 hWnd =new HandleRef(this, hDesktop); hDesktop = Win32Support.GetWindow(hWnd, GW_CHILD);//第3层桌面 break; } return hDesktop; } publicvoid EmbedDesktop(Object embeddedWindow, IntPtr childWindow, IntPtr parentWindow) { Form window = (Form)embeddedWindow; HandleRef HWND_BOTTOM =new HandleRef(embeddedWindow, new IntPtr(1)); constint SWP_FRAMECHANGED =0x0020;//发送窗口大小改变消息 Win32Support.SetParent(childWindow, parentWindow); Win32Support.SetWindowPos(new HandleRef(window, childWindow), HWND_BOTTOM, 300, 300, window.Width, window.Height, SWP_FRAMECHANGED); } } }

2、

using System; using System.Collections.Generic; using System.Text; using System.Runtime.InteropServices; namespace ShowInDesk { class Win32Support { [DllImport("user32.dll", CharSet = CharSet.Auto)] publicstaticextern IntPtr FindWindow(string className, string windowName); [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling =true)] publicstaticextern IntPtr GetWindow(HandleRef hWnd, int nCmd); [DllImport("user32.dll")] publicstaticextern IntPtr SetParent(IntPtr child, IntPtr parent); [DllImport("user32.dll", EntryPoint ="GetDCEx", CharSet = CharSet.Auto, ExactSpelling =true)] publicstaticextern IntPtr GetDCEx(IntPtr hWnd, IntPtr hrgnClip, int flags); [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling =true)] publicstaticexternbool SetWindowPos(HandleRef hWnd, HandleRef hWndInsertAfter, int x, int y, int cx, int cy, int flags); [DllImport("user32.dll")] publicstaticexternint ReleaseDC(IntPtr window, IntPtr handle); } }

3、

namespace ShowInDesk { publicenum DesktopLayer { Progman =0, SHELLDLL =1, FolderView =2 } }

三、
入桌面窗口最底层，并提供详细的实现代码供参考。
此类将窗体永远置于窗口最底层。
首先, 调用一些User32.dll的WinAPI函数。

internal class User32 { public const int SE_SHUTDOWN_PRIVILEGE =0x13; [DllImport("user32.dll")] public static extern IntPtr FindWindow(string lpClassName, string lpWindowName); [DllImport("user32.dll")] public static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent); [DllImport("user32.dll")] public static externbool SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags); }

然后, 在WinForm里面：

public MainForm(){InitializeComponent();try{if (Environment.OSVersion.Version.Major <6){base.SendToBack();IntPtr hWndNewParent = User32.FindWindow("Progman", null);User32.SetParent(base.Handle, hWndNewParent);}else{User32.SetWindowPos(base.Handle, 1, 0, 0, 0, 0, User32.SE_SHUTDOWN_PRIVILEGE);}}catch (ApplicationException exx){MessageBox.Show(this, exx.Message, "Pin to Desktop");}}private void MainForm_Activated(object sender, EventArgs e){if (Environment.OSVersion.Version.Major >=6){User32.SetWindowPos(base.Handle, 1, 0, 0, 0, 0, User32.SE_SHUTDOWN_PRIVILEGE);}}private void MainForm_Paint(object sender, PaintEventArgs e){if (Environment.OSVersion.Version.Major >=6){User32.SetWindowPos(base.Handle, 1, 0, 0, 0, 0, User32.SE_SHUTDOWN_PRIVILEGE);}}

以上介绍的就是C#如何让WinForm嵌入桌面窗口最底层，希望对你有所帮助。