Application.Exit

[DllImport("user32.dll")] 
public static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vlc);
[DllImport("user32.dll")]
public static extern bool UnregisterHotKey(IntPtr hWnd, int id);

const int EXIT_HOTKEY_ID = 1;

// The 6 is a modifier keycode: Alt = 1, Ctrl = 2, Shift = 4, Win = 8
// So 6 is ctrl+shift
RegisterHotKey(this.Handle, MYACTION_HOTKEY_ID, 6, (int) Keys.F4);

protected override void WndProc(ref Message m) 
{
    if (m.Msg == 0x0312 && m.WParam.ToInt32() == EXIT_HOTKEY_ID) 
    {
        // Your hotkey was pressed
    }
    base.WndProc(ref m);
}

using System;
using System.Collections;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Forms;
using System.Windows.Interop;

namespace class
{
    public class HotKey
    {
        private static Hashtable KeyPair = new Hashtable();
        private IntPtr Handle;
        private Window window;
        private uint Controlkey;
        private uint Key;
        private const int WM_HOTKEY = 786;

        public int KeyId { set; get; }

        public event HotKey.OnHotkeyEventHandeler OnHotKey;

        public void Regist(Window win, HotKey.KeyFlags control, Keys key)
        {
            Handle = new WindowInteropHelper(win).Handle;
            window = win;
            Controlkey = (uint)control;
            Key = (uint)key;
            KeyId = (int)Controlkey + (int)Key * 10;
            if (HotKey.KeyPair.ContainsKey((object)KeyId))
                throw new Exception("Error happened HOTKEY 0x12");
            if (!HotKey.RegisterHotKey(Handle, KeyId, Controlkey, Key))
                throw new Exception("Error happened HOTKEY 0x13");
            if (HotKey.KeyPair.Count == 0 && !HotKey.InstallHotKeyHook(this))
                throw new Exception("Error happened HOTKEY 0x12");
            HotKey.KeyPair.Add((object)KeyId, (object)this);
        }

        public void UnRegist(Window win, int KeyId)
        {
            HotKey.UnregisterHotKey(new WindowInteropHelper(win).Handle, KeyId);
        }

        [DllImport("user32")]
        private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint controlKey, uint virtualKey);

        [DllImport("user32")]
        private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

        private static bool InstallHotKeyHook(HotKey hk)
        {
            if (hk.window == null || hk.Handle == IntPtr.Zero)
                return false;
            HwndSource hwndSource = HwndSource.FromHwnd(hk.Handle);
            if (hwndSource == null)
                return false;
            hwndSource.AddHook(new HwndSourceHook(HotKey.HotKeyHook));
            return true;
        }

        private static IntPtr HotKeyHook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            if (msg == 786)
            {
                HotKey hotKey = (HotKey)HotKey.KeyPair[(object)(int)wParam];
                // ISSUE: reference to a compiler-generated field
                if (hotKey.OnHotKey != null)
                {
                    // ISSUE: reference to a compiler-generated field
                    hotKey.OnHotKey();
                }
            }
            return IntPtr.Zero;
        }

        ~HotKey()
        {
            HotKey.UnregisterHotKey(this.Handle, this.KeyId);
        }

        public delegate void OnHotkeyEventHandeler();

        public enum KeyFlags
        {
            Mod_None = 0,
            MOD_ALT = 1,
            MOD_CONTROL = 2,
            MOD_CONTROLALT = 3,
            MOD_SHIFT = 4,
            MOD_WIN = 8,
        }
    }
}

            try {
                HotKey hotKey = new HotKey();
                hotKey.Regist((Window)this, HotKey.KeyFlags.Mod_None, Keys.F9);
                hotKey.OnHotKey += new HotKey.OnHotkeyEventHandeler(your_function);
            } catch { //error }