private void _printersView_CellValueChanged(object sender, DataGridViewCellEventArgs e)
        {
            if (!_isUpdating)
            {
                var    key        = (KeyValuePair <PaperFormat, PaperType>)_printersView.Rows[e.RowIndex].Tag;
                string newPrinter = (string)_printersView["PrinterColumn", e.RowIndex].Value;
                if (PriceManager.ContainsProduct(GetProductKey(key)))
                {
                    if (string.IsNullOrEmpty(newPrinter))
                    {
                        PriceManager.RemoveProduct(GetProductKey(key));
                    }
                    else
                    {
                        PriceManager.GetProduct(GetProductKey(key)).Printer = newPrinter;
                    }
                }
                else if (!string.IsNullOrEmpty(newPrinter))
                {
                    PriceManager.AddProduct(key.Key, key.Value, newPrinter);
                }

                if (Parent is MainForm)
                {
                    (Parent as MainForm).UpdatePriceNodes();
                }
            }
        }