Global hotkeys in WPF working from every window

You can use the same approach as in WinForms with some adaptation:

• use WindowInteropHelper to get HWND (instead of Handle property of a form)
• use HwndSource to handle window messages (instead of overriding WndProc of a form)
• don’t use Key enumeration from WPF – it’s values are not the ones you want

Complete code:

[DllImport("User32.dll")]
private static extern bool RegisterHotKey(
    [In] IntPtr hWnd,
    [In] int id,
    [In] uint fsModifiers,
    [In] uint vk);

[DllImport("User32.dll")]
private static extern bool UnregisterHotKey(
    [In] IntPtr hWnd,
    [In] int id);

private HwndSource _source;
private const int HOTKEY_ID = 9000;

protected override void OnSourceInitialized(EventArgs e)
{
    base.OnSourceInitialized(e);
    var helper = new WindowInteropHelper(this);
    _source = HwndSource.FromHwnd(helper.Handle);
    _source.AddHook(HwndHook);
    RegisterHotKey();
}

protected override void OnClosed(EventArgs e)
{
    _source.RemoveHook(HwndHook);
    _source = null;
    UnregisterHotKey();
    base.OnClosed(e);
}

private void RegisterHotKey()
{
    var helper = new WindowInteropHelper(this);
    const uint VK_F10 = 0x79;
    const uint MOD_CTRL = 0x0002;
    if(!RegisterHotKey(helper.Handle, HOTKEY_ID, MOD_CTRL, VK_F10))
    {
        // handle error
    }
}

private void UnregisterHotKey()
{
    var helper = new WindowInteropHelper(this);
    UnregisterHotKey(helper.Handle, HOTKEY_ID);
}

private IntPtr HwndHook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    const int WM_HOTKEY = 0x0312;
    switch(msg)
    {
        case WM_HOTKEY:
            switch(wParam.ToInt32())
            {
                case HOTKEY_ID:
                    OnHotKeyPressed();
                    handled = true;
                    break;
            }
            break;
    }
    return IntPtr.Zero;
}

private void OnHotKeyPressed()
{
    // do stuff
}