C# - Globale KeyHook

public class KeyHook
    {
        private delegate int HookProc(int nCode, IntPtr wParam, IntPtr lParam);

        //Declare hook handle as int.
        static int hHook = 0;

        public static List<Keys> KeyCodes = new List<Keys>();

        //Declare keyboard hook constant.
        //For other hook types, you can obtain these values from Winuser.h in Microsoft SDK.
        const int WH_KEYBOARD_LL = 13;

        HookProc KeyboardHookProcedure;

        [StructLayout(LayoutKind.Sequential)]
        private class keyboardHookStruct
        {
            public int vkCode;
            public int scanCode;
            public int flags;
            public int time;
            public int dwExtraInfo;
        }

        //Import for SetWindowsHookEx function.
        //Use this function to install thread-specific hook.
        [DllImport("user32.dll", CharSet = CharSet.Auto,
         CallingConvention = CallingConvention.StdCall)]
        private static extern int SetWindowsHookEx(int idHook, HookProc lpfn,
        IntPtr hInstance, int threadId);

        //Import for UnhookWindowsHookEx.
        //Call this function to uninstall the hook.
        [DllImport("user32.dll", CharSet = CharSet.Auto,
         CallingConvention = CallingConvention.StdCall)]
        private static extern bool UnhookWindowsHookEx(int idHook);

        //Import for CallNextHookEx.
        //Use this function to pass the hook information to next hook procedure in chain.
        [DllImport("user32.dll", CharSet = CharSet.Auto,
         CallingConvention = CallingConvention.StdCall)]
        private static extern int CallNextHookEx(int idHook, int nCode,
        IntPtr wParam, IntPtr lParam);

        [DllImport("kernel32.dll")]
        static extern IntPtr LoadLibrary(string lpFileName);

        public KeyHook()
        {
            Hook();
        }

        ~KeyHook()
        {
            UnHook();
        }

        public int Hook()
        {
            KeyboardHookProcedure = new HookProc(KeyHook.KeyboardHookProc);

            hHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardHookProcedure, (IntPtr)LoadLibrary("User32"), 0);
            return hHook;
        }

        public bool UnHook()
        {
            bool ret = UnhookWindowsHookEx(hHook);
            if (ret)
                hHook = 0;
            return ret;
        }

        private static int KeyboardHookProc(int nCode, IntPtr wParam, IntPtr lParam)
        {
            if (nCode < 0)
            {
                return CallNextHookEx(hHook, nCode, wParam, lParam);
            }
            else
            {

                if (((int)wParam == 256) || ((int)wParam == 260))
                {
                    keyboardHookStruct MyKeyboardHookStruct = (keyboardHookStruct)Marshal.PtrToStructure(lParam, typeof(keyboardHookStruct));
                    KeyCodes.Add((Keys)MyKeyboardHookStruct.vkCode);
                }
                return 1;
            }
        }

    }