private void dataGridView_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
if(e.ColumnIndex == _source.Columns["Value"].Ordinal)
{
string error = FilterProperties.CheckFilter(GetFilterProperties(_source.Rows[e.RowIndex]));
if(!string.IsNullOrEmpty(error))
{
MessageBox.Show("Wrong value: " + error, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
_source.Rows[e.RowIndex]["Value"] = null;
_source.Rows[e.RowIndex]["Operator"] = null;
}
}
}