public function onPageLengthSelect($fx = null)
    {
        if (is_callable($fx)) {
            if ($this->cb->triggered()) {
                $this->cb->set(function () use ($fx) {
                    $ipp = @$_GET['ipp'];
                    //$this->pageLength->set(preg_replace("/\[ipp\]/", $ipp, $this->label));
                    $this->set($ipp);
                    $reload = call_user_func($fx, $ipp);
                    if ($reload) {
                        $this->app->terminate($reload->renderJSON());
                    }
                });
            }
        }
    }