private void Cbb_listarusuarios_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            usuarioBLL ub = new usuarioBLL();

            txt_rut.Text = "";
            lb1.Content  = "";
            string rol = "";

            if (coc.IsSelected)
            {
                rol = "Cocinero";
            }
            else if (bart.IsSelected)
            {
                rol = "Bartender";
            }
            else if (Gar.IsSelected)
            {
                rol = "Garzon";
            }
            else if (fina.IsSelected)
            {
                rol = "Finanzas";
            }
            else if (Admin.IsSelected)
            {
                rol = "Administrador";
            }
            else if (caja.IsSelected)
            {
                rol = "caja";
            }
            System.Data.DataTable dt = ub.UserRolList(rol);
            dtg_Usuarios.ItemsSource = dt.DefaultView;
        }