A Global keyboard hook simplified for use outside of WinForms (still requires a Windows window of some sorts though)

GlobalKeyboardLLHook.cs

using System.Runtime.InteropServices;
using SFML.Window;


namespace KH
{
    /*
    **IMPORTANT NOTE**
    this only works if called in a thread which also receives window updates 
    (for example if you call SFMLs RenderWindow.DispatchEvent's function, 
    or in any windows forms or WPF application where you use the same thread)
    */
    public partial class KeyboardHook
    {

        public KeyboardHook() {
            hhook = SetWindowsHookEx(WH_KEYBOARD_LL, _proc, IntPtr.Zero, 0);
        }

        [DllImport("user32.dll")]
        static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc callback, IntPtr hInstance, uint threadId);
 
        [DllImport("user32.dll")]
        static extern bool UnhookWindowsHookEx(IntPtr hInstance);
 
        [DllImport("user32.dll")]
        static extern IntPtr CallNextHookEx(IntPtr idHook, int nCode, int wParam, IntPtr lParam);
 
        [DllImport("kernel32.dll")]
        static extern IntPtr LoadLibrary(string lpFileName);
 
        private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);
 
        const int WH_KEYBOARD_LL = 13;
        const int WM_KEYDOWN = 0x100;
 
        private LowLevelKeyboardProc _proc = hookProc;
 
        private static IntPtr hhook = IntPtr.Zero;

 
        public static void Unhook()
        {
            UnhookWindowsHookEx(hhook);
        }

        ~KeyboardHook() {
            Unhook();
        }

        static HashSet<Keyboard.Key> pressedKeys = new HashSet<Keyboard.Key>();
 
        public static IntPtr hookProc(int code, IntPtr wParam, IntPtr lParam)
        {
            if (code >= 0 && wParam == (IntPtr)WM_KEYDOWN)
            {
                var kbhs = Marshal.PtrToStructure<KbHookStruct>(lParam);

                Console.WriteLine(kbhs.vkCode);
            }
            return CallNextHookEx(hhook, code, (int)wParam, lParam);
        }
    }

    [StructLayout(LayoutKind.Sequential, Pack = 0)]
    struct KbHookStruct {
        public int vkCode;
        public int scanCode;
        public int flags;
        public int time;
        public IntPtr dwExtraInfo;
    }
}