core-bundle/src/Resources/contao/classes/Backend.php
public static function addToUrl($strRequest, $blnAddRef=true, $arrUnset=array())
	{
		// Unset the "no back button" flag
		$arrUnset[] = 'nb';

		return parent::addToUrl($strRequest . (($strRequest != '') ? '&amp;' : '') . 'rt=' . REQUEST_TOKEN, $blnAddRef, $arrUnset);
	}
public static function addToUrl($strRequest, $blnAddRef=true, $arrUnset=array())
	{
		// Unset the "no back button" flag
		$arrUnset[] = 'nb';

		return parent::addToUrl($strRequest . (($strRequest != '') ? '&amp;' : '') . 'rt=' . REQUEST_TOKEN, $blnAddRef, $arrUnset);
	}
Add the request token to the URL

@param string  $strRequest
@param boolean $blnAddRef
@param array   $arrUnset

@return string