public function getNavUrlParams()
    {
        if (($sParams = $this->getViewConfigParam('navurlparams')) === null) {
            $sParams = '';
            $aNavParams = $this->getConfig()->getActiveView()->getNavigationParams();
            foreach ($aNavParams as $sName => $sValue) {
                if (isset($sValue)) {
                    if ($sParams) {
                        $sParams .= '&amp;';
                    }
                    $sParams .= "{$sName}=" . rawurlencode($sValue);
                }
            }
            if ($sParams) {
                $sParams = '&amp;' . $sParams;
            }
            $this->setViewConfigParam('navurlparams', $sParams);
        }

        return $sParams;
    }