Хук клавиатуры перехват сочетаний клавиш

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Diagnostics;
 
namespace KeyHook
{
    public partial class Form1 : Form
    {
        [StructLayout(LayoutKind.Sequential)]
        private struct KBDLLHOOKSTRUCT
        {
            public Keys key;
        }
 
        private delegate IntPtr LowLevelKeyboardProc(
            int nCode, IntPtr wParam, IntPtr lParam);
 
        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr SetWindowsHookEx(
            int id, LowLevelKeyboardProc callback, IntPtr hMod, uint dwThreadId);
 
        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr CallNextHookEx(
            IntPtr hook, int nCode, IntPtr wp, IntPtr lp);
 
        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr GetModuleHandle(string name);
 
        private IntPtr ptrHook;
 
        private LowLevelKeyboardProc objKeyboardProcess;
 
        public Form1()
        {
            InitializeComponent();
 
            ProcessModule objCurrentModule = 
                Process.GetCurrentProcess().MainModule;
            objKeyboardProcess = new LowLevelKeyboardProc(captureKey);
            ptrHook = SetWindowsHookEx(13, objKeyboardProcess, 
                GetModuleHandle(objCurrentModule.ModuleName), 0);
        }
 
        private IntPtr captureKey(int nCode, IntPtr wp, IntPtr lp)
        {
            if (nCode >= 0)
            {
                KBDLLHOOKSTRUCT objKeyInfo = 
                    (KBDLLHOOKSTRUCT)Marshal.PtrToStructure(lp, typeof(KBDLLHOOKSTRUCT));
                if (objKeyInfo.key == Keys.Alt || objKeyInfo.key == Keys.F4)
                {
                    return (IntPtr)1;
                }
            }
            return CallNextHookEx(ptrHook, nCode, wp, lp);
        }
    }
}

if (objKeyInfo.key == Keys.Alt || objKeyInfo.key == Keys.F4)
{
    return (IntPtr)1;
}