private function renderExtraRow($beforeRow, $change, $columnsInExtra)
	{
		$data = $this->dataProvider->data[$beforeRow];
		if ($this->extraRowExpression) { //user defined expression, use it!
			$content = $this->evaluateExpression(
				$this->extraRowExpression,
				array('data' => $data, 'row' => $beforeRow, 'values' => $change['columns'])
			);
		} else { //generate value
			$values = array();
			foreach ($columnsInExtra as $c) {
				$values[] = $change['columns'][$c]['value'];
			}

			$content = '<strong>' . implode(' :: ', $values) . '</strong>';
		}

		$colspan = count($this->columns);

		echo '<tr class="extrarow">';
		$this->extraRowHtmlOptions['colspan'] = $colspan;
		echo CHtml::openTag('td', $this->extraRowHtmlOptions);
		echo $content;
		echo CHtml::closeTag('td');
		echo '</tr>';
	}