// When entering a code, make sure that it is valid.
private void grid_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
{
string newCode = e.FormattedValue.ToString();
string reason;
if (!QueryEvent.IsLegalControlCode(newCode, out reason))
{
// The code isn't valid. Disallow.
((MainFrame)Owner).ErrorMessage(reason);
e.Cancel = true;
}
}