function _flushGroup($new_tag) {
if ($this->_group !== '') {
if ($this->_tag == 'mark') {
$this->_line .= '<span class="diffchange">' . check_plain($this->_group) . '</span>';
}
else {
$this->_line .= check_plain($this->_group);
}
}
$this->_group = '';
$this->_tag = $new_tag;
}