Desktop Functions:

   Smart Device Functions:

Show Recent Changes
Subscribe (RSS)
Misc. Pages
Helpful Tools
Suggested Reading
Website TODO List
Support Forum
Download Visual Studio Add-In

Terms of Use
Privacy Policy
registerhotkey (user32)

C# Signature:

/// <summary> The RegisterHotKey function defines a system-wide hot key </summary>
/// <param name="hwnd">Handle to the window that will receive WM_HOTKEY messages
/// generated by the hot key.</param>
/// <param name="id">Specifies the identifier of the hot key.</param>
/// <param name="fsModifiers">Specifies keys that must be pressed in combination with the key
/// specified by the 'vk' parameter in order to generate the WM_HOTKEY message.</param>
/// <param name="vk">Specifies the virtual-key code of the hot key</param>
/// <returns><c>true</c> if the function succeeds, otherwise <c>false</c></returns>
/// <seealso cref=""/>
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers,
   uint vk);

VB Signature:

Public Declare Function RegisterHotKey Lib "user32" Alias "RegisterHotKey" (ByVal hwnd As Long, ByVal id As Long, ByVal fsModifiers As Long, ByVal vk As Long) As Long Signature:

Declare Auto Function registerhotkey Lib "user32.dll" (Byval handle As IntPtr, ByVal id As Integer, ByVal fsModifier As Integer, ByVal vk As Integer) As Integer

User-Defined Types:




Tips & Tricks:

Please add some!

Sample Code:

    // c#
    public class WindowsShell
        #region fields
        public static int MOD_ALT = 0x1;
        public static int MOD_CONTROL = 0x2;
        public static int MOD_SHIFT = 0x4;
        public static int MOD_WIN = 0x8;
        public static int WM_HOTKEY = 0x312;

        private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vlc);

        private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

        private static int keyId;
        public static void RegisterHotKey(Form f, Keys key)
            int modifiers = 0;

            if ((key & Keys.Alt) == Keys.Alt)
                modifiers = modifiers | WindowsShell.MOD_ALT;

            if ((key & Keys.Control) == Keys.Control)
                modifiers = modifiers | WindowsShell.MOD_CONTROL;

            if ((key & Keys.Shift) == Keys.Shift)
                modifiers = modifiers | WindowsShell.MOD_SHIFT;

            Keys k = key & ~Keys.Control & ~Keys.Shift & ~Keys.Alt;

            Func ff = delegate()
                    keyId = f.GetHashCode(); // this should be a key unique ID, modify this if you want more than one hotkey
                    RegisterHotKey((IntPtr)f.Handle, keyId, modifiers, (int)k);

            f.Invoke(ff); // this should be checked if we really need it (InvokeRequired), but it's faster this way

        private delegate void Func();

        public static void UnregisterHotKey(Form f)
                Func ff = delegate()
                    UnregisterHotKey(f.Handle, keyId); // modify this if you want more than one hotkey

                f.Invoke(ff); // this should be checked if we really need it (InvokeRequired), but it's faster this way
            catch (Exception ex)

    public partial class Form1 : Form, IDisposable
        protected override void OnLoad(EventArgs e)
            Keys k = Keys.A | Keys.Control;
            WindowsShell.RegisterHotKey(this, k);

        // CF Note: The WndProc is not present in the Compact Framework (as of vers. 3.5)! please derive from the MessageWindow class in order to handle WM_HOTKEY
        protected override void WndProc(ref Message m)
            base.WndProc(ref m);

            if (m.Msg == WindowsShell.WM_HOTKEY)
                this.Visible = !this.Visible;

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)

Sample Code:

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Threading;

/// <summary> This class allows you to manage a hotkey </summary>
public class GlobalHotkeys : IDisposable
    [DllImport( "user32", SetLastError = true )]
    [return: MarshalAs( UnmanagedType.Bool )]
    public static extern bool RegisterHotKey (IntPtr hwnd, int id, int fsModifiers, int vk);
    [DllImport( "user32", SetLastError = true )]
    public static extern int UnregisterHotKey (IntPtr hwnd, int id);
    [DllImport( "kernel32", SetLastError = true )]
    public static extern short GlobalAddAtom (string lpString);
    [DllImport( "kernel32", SetLastError = true )]
    public static extern short GlobalDeleteAtom (short nAtom);

    public const int MOD_ALT = 1;
    public const int MOD_CONTROL = 2;
    public const int MOD_SHIFT = 4;
    public const int MOD_WIN = 8;

    public const int WM_HOTKEY = 0x312;

    public GlobalHotkeys () {
    this.Handle = Process.GetCurrentProcess().Handle;

    /// <summary> handle of the current process </summary>
    public IntPtr Handle;

    /// <summary> the ID for the hotkey </summary>
    public short HotkeyID {
    private set;

    /// <summary> register the hotkey </summary>
    public void RegisterGlobalHotKey (int hotkey, int modifiers, IntPtr handle) {
    this.Handle = handle;
    RegisterGlobalHotKey( hotkey, modifiers );

    /// <summary> register the hotkey </summary>
    public void RegisterGlobalHotKey (int hotkey, int modifiers) {

    try {
        // use the GlobalAddAtom API to get a unique ID (as suggested by MSDN docs)
        string atomName = Thread.CurrentThread.ManagedThreadId.ToString( "X8" ) + this.GetType().FullName;
        HotkeyID = GlobalAddAtom( atomName );
        if ( HotkeyID == 0 )
        throw new Exception( "Unable to generate unique hotkey ID. Error: " + Marshal.GetLastWin32Error().ToString() );

        // register the hotkey, throw if any error
        if ( !RegisterHotKey( this.Handle, HotkeyID, modifiers, (int) hotkey ) )
        throw new Exception( "Unable to register hotkey. Error: " + Marshal.GetLastWin32Error().ToString() );

    } catch ( Exception e ) {
        // clean up if hotkey registration failed
        Console.WriteLine( e );

    /// <summary> unregister the hotkey </summary>
    public void UnregisterGlobalHotKey () {
    if ( this.HotkeyID != 0 ) {
        UnregisterHotKey( this.Handle, HotkeyID );
        // clean up the atom list
        GlobalDeleteAtom( HotkeyID );
        HotkeyID = 0;

    public void Dispose () {

How to use :

GlobalHotkeys hotkey;

hotkey = new GlobalHotkeys();
hotkey.RegisterGlobalHotKey( (int) Keys.F11, GlobalHotkeys.MOD_CONTROL );

protected override void WndProc (ref Message m) {
     const int WM_HOTKEY = 0x0312;

     switch ( m.Msg ) {
     case WM_HOTKEY:
         if ( (short) m.WParam == hotkey.HotkeyID ) {
         // do your thing
         base.WndProc( ref m );

Alternative Managed API:

The ManagedWindowsApi project ( provides a

Hotkey class to register global hotkeys.


Please edit this page!

Do you have...

  • helpful tips or sample code to share for using this API in managed code?
  • corrections to the existing content?
  • variations of the signature you want to share?
  • additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).

Access directly from VS:
Terms of Use
Find References
Show Printable Version