public void OnSaveChange(SPField field, bool isNewField)
        {
            EnsureChildControls();

            _lookupFieldEditor.OnSaveChange(field, isNewField);

            field.SetFieldAttribute("Filter", filterTextBox.Text);
            field.SetFieldAttribute("MaxHeight", maxHeightTextBox.Text);
            field.SetFieldAttribute("MaxRows", maxRowsTextBox.Text);
            field.SetFieldAttribute("MinLength", minLengthTextBox.Text);
            field.SetFieldAttribute("TitleField", titleFieldTextBox.Text);
            field.SetFieldAttribute("ValueField", valueFieldTextBox.Text);
            field.SetFieldAttribute("DescriptionFields", descriptionFieldsTextBox.Text);
        }