code: public function getContentElements()
  	{
  		$groups = array();
  
  		foreach ($GLOBALS['TL_CTE'] as $k=>$v)
  		{
  			foreach (array_keys($v) as $kk)
  			{
  				$groups[$k][] = $kk;
  			}
  		}
  
  		return $groups;
  	}
docs: Return all content elements as array
  
  @return array