如何从.NET锁定Windows(如"Windows + L")？

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

public class KeyboardHook
{
    private const int WM_HOTKEY = 0x312;
    private const int MOD_ALT = 0x1;
    private const int MOD_CONTROL = 0x2;
    private const int MOD_SHIFT = 0x4;
    private const int MOD_WIN = 0x8;

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

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

    private int key;
    private IntPtr hWnd;
    private int id;

    public event EventHandler HotKeyPressed;

    public KeyboardHook(int key, Keys modifiers, Form form)
    {
        this.key = key;
        this.hWnd = form.Handle;
        id = this.GetHashCode();
        RegisterHotKey();
        form.Disposed += (sender, args) => UnregisterHotKey();
    }

    private void RegisterHotKey()
    {
        if (!RegisterHotKey(hWnd, id, GetModifierFlag(), key))
        {
            throw new ApplicationException("Unable to register hot key.");
        }
    }

    private void UnregisterHotKey()
    {
        UnregisterHotKey(hWnd, id);
    }

    private int GetModifierFlag()
    {
        return 0;
    }

    protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM_HOTKEY && (int)m.WParam == id)
        {
            OnHotKeyPressed();
        }

        base.WndProc(ref m);
    }

    private void OnHotKeyPressed()
    {
        HotKeyPressed?.Invoke(this, EventArgs.Empty);
    }
}

private KeyboardHook keyboardHook;

private void InitializeKeyboardHook()
{
    keyboardHook = new KeyboardHook(Keys.L, Keys.None, this);
    keyboardHook.HotKeyPressed += (sender, args) => LockWorkStation();
}

[DllImport("user32.dll")]
private static extern bool LockWorkStation();

public MainForm()
{
    InitializeComponent();
    InitializeKeyboardHook();
}