private void txtDef_TextChanged(object sender, System.EventArgs e)
 {
     if (item != null)
     {
         try
         {
             item.SubItems[3].Text = txtDef.Text;
             fields[item.Index].SetValue(EPField.StringToTypedValue(fields[item.Index].OleDbType, txtDef.Text));
             if (fields[item.Index].Value == null)
             {
                 item.SubItems[3].Text = "";
             }
             else
             {
                 item.SubItems[3].Text = fields[item.Index].Value.ToString();
             }
         }
         catch
         {
         }
     }
 }