lib.php

<?php
    function local_comments_extend_settings_navigation($settingsnav, $context) {
        global $CFG, $PAGE;

        // Only add this settings item on non-site course pages.
        if (!$PAGE->course or $PAGE->course->id == 1) {
            return;
        }

        // Only let users with the appropriate capability see this settings item.
        if (!has_capability('moodle/backup:backupcourse', context_course::instance($PAGE->course->id))) {
            return;
        }

        if ($settingnode = $settingsnav->find('courseadmin', navigation_node::TYPE_COURSE)) {
            $strfoo = get_string('foo', 'local_comments');
            $url = new moodle_url('/local/comments/foo.php', array('id' => $PAGE->course->id));
            $foonode = navigation_node::create(
                $strfoo,
                $url,
                navigation_node::NODETYPE_LEAF,
                'comments',
                'comments',
                new pix_icon('t/addcontact', $strfoo)
            );
            if ($PAGE->url->compare($url, URL_MATCH_BASE)) {
                $foonode->make_active();
            }
            $settingnode->add_node($foonode);
        }
    }
?>