Sugar 7 Mobile UI - allow use of modules as subpanels without adding to the navigation menu. First add the module(s) through the typical Mobile Configuration tool, then create a hard-coded list in the CustomMetadataAPI class like below.

CustomMetadataApi.php

<?php
require_once('clients/base/api/MetadataApi.php');

/**
 * custom/clients/base/api/CustomMetadataApi.php
 */
class CustomMetadataApi extends MetadataApi
{

    /**
     * Extends MetadataApi::getAllMetadata() to ensure that specific modules
     * are not shown in the Mobile Navigation menu, while still allowing the
     * subpanels referencing these modules to be used.
     *
     * @param ServiceBase $api
     * @param array $args
     * @return array
     */
    public function getAllMetadata(ServiceBase $api, array $args)
    {
        $data = parent::getAllMetadata($api, $args);

        if ($api->platform == 'mobile') {
            $modules_to_hide = array(
                'Calls',
                'Meetings',
                'Tasks',
            );

            foreach ($modules_to_hide as $module) {
                if (!empty($data['modules_info'][$module])) {
                    $data['modules_info'][$module]['display_tab'] = false;
                    $data['modules_info'][$module]['enabled'] = true;
                    $data['modules_info'][$module]['quick_create'] = false;
                    $data['modules_info'][$module]['show_subpanels'] = true;
                    $data['modules_info'][$module]['visible'] = false;
                }
            }

        }

        return $data;

    }
}