public function isExtendedSearch()
    {
        $result = false;

        if (array_key_exists('extended', $this->requestArguments)) {
            // Show extended search when told so by the »extended« argument.
            $result = (true == $this->requestArguments['extended']);
        } else {
            // Show extended search when any of the »extended« fields are used.
            if (array_key_exists('q', $this->requestArguments)) {
                foreach ($this->settings['queryFields'] as $fieldInfo) {
                    if ($fieldInfo['extended']
                        && array_key_exists($fieldInfo['id'], $this->requestArguments['q'])
                        && $this->requestArguments['q'][$fieldInfo['id']]
                    ) {
                        $result = true;
                        break;
                    }
                }
            }
        }

        return $result;
    }