private void gestionPaísToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (formPais == null)
            {
                formPais             = new FormGestionPais();
                formPais.MdiParent   = this;
                formPais.FormClosed += new FormClosedEventHandler(formPais_FormClosed);

                formPais.Show();
            }
            else
            {
                formPais.Activate();
            }
        }
 private void formPais_FormClosed(object sender, FormClosedEventArgs e)
 {
     formPais = null;
 }