private void zonaToolStripMenuItem_Click(object sender, EventArgs e)
{
frmDM_Zona o = new frmDM_Zona(null);
o.MdiParent = this;
o.Show();
}
private void btnGoZona_Click(object sender, EventArgs e)
{
eZONA o = new eZONA();
o.ZON_codigo = this.cmbZona.SelectedValue != null?Convert.ToInt32(this.cmbZona.SelectedValue.ToString()) : -1;
frmDM_Zona o2 = new frmDM_Zona(o);
o2.MdiParent = this.MdiParent;
o2.Show();
}