Global hotkeys for c# WPF application

GlobalHotkeyWindow.cs

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

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        const int MYACTION_HOTKEY_ID = 1;

        public MainWindow()
        {
            InitializeComponent();
        }

        // DLL libraries used to manage hotkeys
        [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);

        private static IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            if (msg == 0x0312)
            {
                Console.WriteLine("resr");
            }

            return IntPtr.Zero;
        }

        [Flags]
        public enum Modifiers
        {
            NoMod = 0x0000,
            Alt = 0x0001,
            Ctrl = 0x0002,
            Shift = 0x0004,
            Win = 0x0008
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            var source = PresentationSource.FromVisual(this as Visual) as HwndSource;
            if (source == null)
                throw new Exception("Could not create hWnd source from window.");
            source.AddHook(WndProc);

            RegisterHotKey(new WindowInteropHelper(this).Handle, MYACTION_HOTKEY_ID, (int)Modifiers.Ctrl, (int)Keys.A);
            RegisterHotKey(new WindowInteropHelper(this).Handle, 2, (int)Modifiers.Ctrl, (int)Keys.S);
            RegisterHotKey(new WindowInteropHelper(this).Handle, 3, (int)Modifiers.Ctrl, (int)Keys.D);
        }
    }
}