public function addTabItem($title, $docobj, $tabdefault = false)
	{
		if (is_null($docobj) || !($docobj instanceof IXmlnukeDocumentObject)) 
		{
			throw new InvalidArgumentException("Object is null or not is IXmlnukeDocumentObject. Found object type: " . get_class($docobj), 853);
		}
		$this->_tabs[] = array($title, "OBJ", $docobj);
		if ($tabdefault)
		{
			$this->_tabDefault = count($this->_tabs)-1;
		}
	}