private void frmConfirmInvoice_Load(object sender, EventArgs e)        {            ArrayList list = new ArrayList();            list.Add(new DictionaryEntry("A", "1"));            list.Add(new DictionaryEntry("B", "2"));            list.Add(new DictionaryEntry("C", "3"));            cmbClass.DataSource = list;            cmbClass.DisplayMember = "Key";            cmbClass.ValueMember = "Value";        }