private void dgwListe_CellMouseUp(object sender, DataGridViewCellMouseEventArgs e)
        {
            int iContatti = 0;
            DataGridViewCheckBoxCell cbxCell;

            foreach (DataGridViewRow row in dgwListe.Rows)
            {
                cbxCell = row.Cells["ID"] as DataGridViewCheckBoxCell;

                bool bChecked = (null != cbxCell && null != cbxCell.Value && true == (bool)cbxCell.Value);

                if (true == bChecked)
                {
                    iContatti += Convert.ToInt32(row.Cells["Contatti"].Value);
                }
            }

            lblDisplay.Text = "Sono stati selezionati ( " + Convert.ToString(iContatti) + " ) indirizzi a cui inviare la newsletter.";
        }