下面看一下本人修改自网络常见的代码：

public delegate void HotkeyEventHandler(int HotKeyID);

public class SystemHotKey : System.Windows.Forms.IMessageFilter
    {
        List<UInt32> keyIDs = new List<UInt32>();
        IntPtr hWnd;

public event HotkeyEventHandler OnHotkey;

public enum KeyFlags
        {
            Alt = 0x1,
            Ctrl = 0x2,
            Shift = 0x4,
            Win = 0x8,
            //组合键等于值相加
            Alt_Ctrl = 0x3,
            Alt_Shift = 0x5,
            Ctrl_Shift = 0x6,
            Alt_Ctrl_Shift = 0x7
        }
        [DllImport("user32.dll")]
        public static extern UInt32 RegisterHotKey(IntPtr hWnd, UInt32 id, UInt32 fsModifiers, UInt32 vk);

[DllImport("user32.dll")]
        public static extern UInt32 UnregisterHotKey(IntPtr hWnd, UInt32 id);

[DllImport("kernel32.dll")]
        public static extern UInt32 GlobalAddAtom(String lpString);

[DllImport("kernel32.dll")]
        public static extern UInt32 GlobalDeleteAtom(UInt32 nAtom);

public SystemHotKey(IntPtr hWnd)
        {
            this.hWnd = hWnd;
        }

public int RegisterHotkey(KeyFlags keyflags, System.Windows.Forms.Keys Key)
        {
            System.Windows.Forms.Application.AddMessageFilter(this);
            UInt32 hotkeyid = GlobalAddAtom(System.Guid.NewGuid().ToString());
            RegisterHotKey((IntPtr)hWnd, hotkeyid, (UInt32)keyflags, (UInt32)Key);
            keyIDs.Add(hotkeyid);
            return (int)hotkeyid;
        }

public void UnregisterHotkeys()
        {
            if (keyIDs.Count > 0)
            {

System.Windows.Forms.Application.RemoveMessageFilter(this);
                foreach (UInt32 key in keyIDs)
                {
                    UnregisterHotKey(hWnd, key);
                    GlobalDeleteAtom(key);
                }
                keyIDs.Clear();
            }
        }

public bool PreFilterMessage(ref   System.Windows.Forms.Message m)
        {
            if (m.Msg == 0x312)
            {
                if (OnHotkey != null)
                {
                    foreach (UInt32 key in keyIDs)
                    {
                        if ((UInt32)m.WParam == key)
                        {
                            OnHotkey((int)m.WParam);
                            return true;
                        }
                    }
                }
            }
            return false;
        }
    }

1：System.Windows.Forms.Application.AddMessageFilter(this);这句需要对应System.Windows.Forms.Application.RemoveMessageFilter(this);这里用完要记得取消。

由于原来的程序，只在构造函数里添加，所以取消后，再设置就会失效了，这里直接在注册的时候给加上，取消时去掉，注意下这个效果即可。

这个是不经意思发觉的，网上的代码都没有提到，估计转的人太多了，知道的又不写出来。

3：把Hastable变更成List<Unint32>方式。