此时希望用户不能通过键盘alt+F4来结束程序及通过Win的组合键对窗口进行操作。我在网上搜索了一下，采用全局键盘钩子的方法可以做到屏蔽用户对键盘的操作。。以下为相关代码，用到了Form1_load事件和Form1_FormClosing事件：
代码如下：

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;
using System.Reflection;
namespace WindowsApplication10
{
public partial class Form1 : Form
{
// 安装钩子
[DllImport("user32.dll")]
public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);
// 卸载钩子
[DllImport("user32.dll")]
public static extern bool UnhookWindowsHookEx(int idHook);
// 继续下一个钩子
[DllImport("user32.dll")]
public static extern int CallNextHookEx(int idHook, int nCode, Int32 wParam, IntPtr lParam);
//声明定义
public delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);
static int hKeyboardHook = 0;
HookProc KeyboardHookProcedure;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
HookStart();
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
HookStop();
}
// 安装钩子
public void HookStart()
{
if (hKeyboardHook == 0)
{
// 创建HookProc实例
KeyboardHookProcedure = new HookProc(KeyboardHookProc);
//定义全局钩子
hKeyboardHook = SetWindowsHookEx(13, KeyboardHookProcedure, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);
if (hKeyboardHook == 0)
{
HookStop();
throw new Exception("SetWindowsHookEx failed.");
}
}
}
//钩子子程就是钩子所要做的事情。
private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam)
{
//这里可以添加别的功能的代码
return 1;
}
// 卸载钩子
public void HookStop()
{
bool retKeyboard = true;
if (hKeyboardHook != 0)
{
retKeyboard = UnhookWindowsHookEx(hKeyboardHook);
hKeyboardHook = 0;
}
if (!(retKeyboard)) throw new Exception("UnhookWindowsHookEx failed.");
}
}
}

（注：该方法可以屏蔽win和alt+F4但是不能屏蔽ctrl+alt+del）