Question

How to disable Alt+⇧Shift+↹Tab using c# ? I have disabled the Alt+↹Tab using a function which gets only two parameters. But to disable three key strokes ??

I anyone need my code to disable the two key strokes combination, i cam post it. But it is quite big.

To disable Alt+↹Tab I do this,

RegisterGlobalHotKey(Keys.Tab, USE_ALT); 

How to pass three parameters [Alt, Shift, Tab] ??

   public sealed class KeyboardHook : IDisposable
{
    // Registers a hot key with Windows.
    [DllImport("user32.dll")]
    private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);
    // Unregisters the hot key with Windows.
    [DllImport("user32.dll")]
    private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

    /// <summary>
    /// Represents the window that is used internally to get the messages.
    /// </summary>
    private class Window : NativeWindow, IDisposable
    {
        private static int WM_HOTKEY = 0x0312;

        public Window()
        {
            // create the handle for the window.
            try
            {
                this.CreateHandle(new CreateParams());
            }
            catch (Exception ex)
            {
                ExceptionHandler.writeToLogFile(System.Environment.NewLine + "Target  :  " + ex.TargetSite.ToString() + System.Environment.NewLine + "Message :  " + ex.Message.ToString() + System.Environment.NewLine + "Stack   :  " + ex.StackTrace.ToString());
            }
        }

        /// <summary>
        /// Overridden to get the notifications.
        /// </summary>
        /// <param name="m"></param>
        protected override void WndProc(ref Message m)
        {
            try
            {
                base.WndProc(ref m);

                // check if we got a hot key pressed.
                if (m.Msg == WM_HOTKEY)
                {
                    // get the keys.
                    Keys key = (Keys)(((int)m.LParam >> 16) & 0xFFFF);
                    ModifierKeys modifier = (ModifierKeys)((int)m.LParam & 0xFFFF);

                    // invoke the event to notify the parent.
                    if (KeyPressed != null)
                        KeyPressed(this, new KeyPressedEventArgs(modifier, key));
                }
            }
            catch (Exception ex)
            {
                ExceptionHandler.writeToLogFile(System.Environment.NewLine + "Target  :  " + ex.TargetSite.ToString() + System.Environment.NewLine + "Message :  " + ex.Message.ToString() + System.Environment.NewLine + "Stack   :  " + ex.StackTrace.ToString());
            }
        }

        public event EventHandler<KeyPressedEventArgs> KeyPressed;

        #region IDisposable Members

        public void Dispose()
        {
            this.DestroyHandle();
        }

        #endregion
    }

    private Window _window = new Window();
    private int _currentId;

    public KeyboardHook()
    {
        try
        {
            // register the event of the inner native window.
            _window.KeyPressed += delegate(object sender, KeyPressedEventArgs args)
            {
                if (KeyPressed != null)
                    KeyPressed(this, args);
            };
        }
        catch (Exception ex)
        {
            ExceptionHandler.writeToLogFile(System.Environment.NewLine + "Target  :  " + ex.TargetSite.ToString() + System.Environment.NewLine + "Message :  " + ex.Message.ToString() + System.Environment.NewLine + "Stack   :  " + ex.StackTrace.ToString());
        }
    }

    /// <summary>
    /// Registers a hot key in the system.
    /// </summary>
    /// <param name="modifier">The modifiers that are associated with the hot key.</param>
    /// <param name="key">The key itself that is associated with the hot key.</param>
    public void RegisterHotKey(ModifierKeys modifier, Keys key)
    {
        try
        {
            // increment the counter.
            _currentId = _currentId + 1;

            // register the hot key.
            if (!RegisterHotKey(_window.Handle, _currentId, (uint)modifier, (uint)key))
                throw new InvalidOperationException("Couldn’t register the hot key.");
        }
        catch (Exception ex)
        {
            ExceptionHandler.writeToLogFile(System.Environment.NewLine + "Target  :  " + ex.TargetSite.ToString() + System.Environment.NewLine + "Message :  " + ex.Message.ToString() + System.Environment.NewLine + "Stack   :  " + ex.StackTrace.ToString());
        }
    } 

    /// <summary>
    /// A hot key has been pressed.
    /// </summary>
    public event EventHandler<KeyPressedEventArgs> KeyPressed;

    #region IDisposable Members

    public void Dispose()
    {
        // unregister all the registered hot keys.
        for (int i = _currentId; i > 0; i--)
        {
            UnregisterHotKey(_window.Handle, i);
        }

        // dispose the inner native window.
        _window.Dispose();
    }

    #endregion
}

/// <summary>
/// Event Args for the event that is fired after the hot key has been pressed.
/// </summary>
public class KeyPressedEventArgs : EventArgs
{
    private ModifierKeys _modifier;
    private Keys _key;

    internal KeyPressedEventArgs(ModifierKeys modifier, Keys key)
    {
        _modifier = modifier;
        _key = key;
    }

    public ModifierKeys Modifier
    {
            get { return _modifier; }
        }

        public Keys Key
        {
            get { return _key; }
        }
    }

    /// <summary>
    /// The enumeration of possible modifiers.
    /// </summary>
    [Flags]
    public enum ModifierKeys : uint
    {
        Alt = 1,
        Control = 2,
        Shift = 4,
        Win = 8
    }

Answer 1

You mention you use a function which takes 2 parameters but you didn’t mention which function it was. In any case, Keys.Shift and Keys.Alt are modifier keys so whatever you are passing “Alt” into you would probably need to bitwise OR that with “Shift”.

In WPF this would be something like:

var altShift = Keys.Alt | Keys.Shift;