如何使用WPF和.NET 3.5注册全局热键来说CTRL + SHIFT +(LETTER)？

using System;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Input;

namespace GlobalHotKeyExample
{
    public partial class MainWindow : Window
    {
        [DllImport("user32.dll")]
        private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);

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

        private const int WM_HOTKEY = 0x0312;

        public MainWindow()
        {
            InitializeComponent();

            ComponentDispatcher.ThreadPreprocessMessage += ComponentDispatcher_ThreadPreprocessMessage;

            // 注册全局热键
            RegisterHotKey(new KeyGesture(Key.A, ModifierKeys.Control | ModifierKeys.Shift));
        }

        private void ComponentDispatcher_ThreadPreprocessMessage(ref MSG msg, ref bool handled)
        {
            if (msg.message == WM_HOTKEY)
            {
                int id = (int)msg.wParam;
                // 在这里处理热键事件
                MessageBox.Show("全局热键被按下！");
            }
        }

        protected override void OnClosed(EventArgs e)
        {
            ComponentDispatcher.ThreadPreprocessMessage -= ComponentDispatcher_ThreadPreprocessMessage;
            base.OnClosed(e);
        }

        private void RegisterHotKey(KeyGesture keyGesture)
        {
            int keyCode = KeyInterop.VirtualKeyFromKey(keyGesture.Key);
            uint modifiers = 0;

            if ((keyGesture.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
            {
                modifiers |= (uint)Win32.MOD_CONTROL;
            }

            if ((keyGesture.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift)
            {
                modifiers |= (uint)Win32.MOD_SHIFT;
            }

            if (!RegisterHotKey(this.GetHandle(), keyCode, modifiers, keyCode))
            {
                throw new Exception("注册热键失败！");
            }
        }

        private IntPtr GetHandle()
        {
            return new WindowInteropHelper(this).Handle;
        }
    }
}