private void btnVolver_Click(object sender, RoutedEventArgs e)
{
VisualizarVentas visv = new VisualizarVentas();
visv.Show();
this.Close();
}
private void btnVerVentas_Click(object sender, RoutedEventArgs e)
{
VisualizarVentas vv = new VisualizarVentas(nomUsuario);
vv.Show();
this.Close();
}