private void Button_Click(object sender, RoutedEventArgs e)
        {
            UsuarioTextBox.Text    = "Mario";
            ContrasenaTextBox.Text = "******";
            VentanaCliente ventana = new VentanaCliente();

            ventana.Owner = this;
            ventana.ShowDialog();
        }
        private void Button_Click(object sender, RoutedEventArgs e)
        {
            VentanaCliente ventana = new VentanaCliente();

            ventana.Show();
        }