theme_location) || empty(!empty($_wp_registered_nav_menus[$args->theme_location]))): ?>

<?php quadmenu(array(theme_location => "%1$s")); ?>', key($_wp_registered_nav_menus)); ?>

Configuration tab and activate the %2$s theme location.', 'quadmenu'), QuadMenu::taburl('0'), $_wp_registered_nav_menus[$args->theme_location]); ?>