private void Window_SourceInitialized(object sender, EventArgs e) { IntPtr windowHandle = (new WindowInteropHelper(this)).Handle; HwndSource src = HwndSource.FromHwnd(windowHandle); src.AddHook(new HwndSourceHook(WndProc)); try { m_SystemMenu = SystemMenu.FromWPFForm(this); m_SystemMenu.AppendSeparator(); m_SystemMenu.AppendMenu(m_UrlID, "Copy Current URL"); } catch (NoSystemMenuException) { } }