private void Cancelar_add_Click(object sender, RoutedEventArgs e)
        {
            Gestionar_plataforma gestionar = new Gestionar_plataforma();

            gestionar.Show();
            this.Close();
        }
        private void plat_Selected(object sender, RoutedEventArgs e)
        {
            Gestionar_plataforma gestionar = new Gestionar_plataforma();

            gestionar.Show();
            this.Close();
        }