private void ShowContextMenu()
{
    if ((this.contextMenu != null) || (this.contextMenuStrip != null))
    {
        NativeMethods.POINT pt = new NativeMethods.POINT();
        UnsafeNativeMethods.GetCursorPos(pt);
        UnsafeNativeMethods.SetForegroundWindow(new HandleRef(this.window, this.window.Handle));
        if (this.contextMenu != null)
        {
            this.contextMenu.OnPopup(EventArgs.Empty);
            SafeNativeMethods.TrackPopupMenuEx(new HandleRef(this.contextMenu, this.contextMenu.Handle), 0x48, pt.x, pt.y, new HandleRef(this.window, this.window.Handle), null);
            UnsafeNativeMethods.PostMessage(new HandleRef(this.window, this.window.Handle), 0, IntPtr.Zero, IntPtr.Zero);
        }
        else if (this.contextMenuStrip != null)
        {
            this.contextMenuStrip.ShowInTaskbar(pt.x, pt.y);
        }
    }
}