TYPO3 4.7 with ext: getcontentbyajax - ajax

Question

The json output is not generated by Ext getcontentbyajax in TYPO3 ver. 4.7. It invokes an 500 Internal server error. In the serverlog i found the error is in line 42 of /lib/class.tx_getcontentbyajax.php.
switch(t3lib_div::_GP('todo')){
I found a 4.7 issue on:
http://lists.typo3.org/pipermail/typo3-german/2012-September/087865.html
t3lib_div::GPvar() changes to t3lib_div::_GP()
When you change all GPvar's to _GP the extension works fine.
Here the changed method main() form /lib/class.tx_getcontentbyajax.php of getcontentbyajax extension:
public function main(){
switch(t3lib_div::_GP('todo')){
case 'pagebrowser':
$href = str_replace(t3lib_div::getIndpEnv('TYPO3_SITE_URL'), '', t3lib_div::_GP('href')); // IE6 has problems
$requestedPage = file_get_contents(urldecode(t3lib_div::getIndpEnv('TYPO3_SITE_URL') . $href));
/*preg_match('/<div.*?id\=[\"]{0,1}' . t3lib_div::GPvar('part') . '[\"]{0,1}.*?>[\r\n]{0,2}<!--ajaxreplace-->[\s]{0,}(.*?)[\s]{0,}<!--ajaxreplace-->[\r\n]{0,2}<\/div>/s', $requestedPage, $matches);*/
preg_match('/<!--ajaxreplace-->(.*?)<!--ajaxreplace-->/s', $requestedPage, $matchesContent);
preg_match('/<title>(.*?)<\/title>/s', $requestedPage, $matchesTitle);
if(array_key_exists(1, $matchesContent)){
if(array_key_exists(1, $matchesTitle)){
$this->data['title'] = $matchesTitle[1];
}
$this->data['content'] = $matchesContent[1];
$this->data['success'] = true;
} else {
$this->data['content'] = 'An error occured, please reload the site or click this link to load your desired page.';
$this->data['success'] = false;
}
// hook
if (is_array($GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['getcontentbyajax']['mainHook'])){
foreach ($GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['getcontentbyajax']['mainHook'] as $_classRef){
$_procObj = & t3lib_div::getUserObj($_classRef);
$this->data = $_procObj->extraGlobalMarkerProcessor($this, $this->data);
}
}
break;
}
echo json_encode($this->data);
}