public function messages_metabox($event, $callback_args)
    {
        //let's get the active messengers (b/c messenger objects have the active message templates)
        //convert 'evt_id' to 'EVT_ID'
        $this->_req_data['EVT_ID'] = isset($this->_req_data['EVT_ID']) ? $this->_req_data['EVT_ID'] : NULL;
        $this->_req_data['EVT_ID'] = isset($this->_req_data['post']) && empty($this->_req_data['EVT_ID']) ? $this->_req_data['post'] : $this->_req_data['EVT_ID'];
        $this->_req_data['EVT_ID'] = empty($this->_req_data['EVT_ID']) && isset($this->_req_data['evt_id']) ? $this->_req_data['evt_id'] : $this->_req_data['EVT_ID'];
        $EEM_controller = new EE_messages();
        $active_messengers = $EEM_controller->get_active_messengers();
        $tabs = array();
        //empty messengers?
        //Note message types will always have at least one available because every messenger has a default message type associated with it (payment) if no other message types are selected.
        if (empty($active_messengers)) {
            $msg_activate_url = EE_Admin_Page::add_query_args_and_nonce(array('action' => 'settings'), EE_MSG_ADMIN_URL);
            $error_msg = sprintf(__('There are no active messengers. So no notifications will go out for <strong>any</strong> events.  You will want to %sActivate a Messenger%s.', 'event_espresso'), '<a href="' . $msg_activate_url . '">', '</a>');
            $error_content = '<div class="error"><p>' . $error_msg . '</p></div>';
            $internal_content = '<div id="messages-error"><p>' . $error_msg . '</p></div>';
            echo $error_content;
            echo $internal_content;
            return;
        }
        $event_id = isset($this->_req_data['EVT_ID']) ? $this->_req_data['EVT_ID'] : NULL;
        //get content for active messengers
        foreach ($active_messengers as $name => $messenger) {
            //first check if there are any active message types for this messenger.
            $active_mts = $EEM_controller->get_active_message_types_per_messenger($name);
            if (empty($active_mts)) {
                continue;
            }
            $tcont = $messenger->get_messenger_admin_page_content('events', 'edit', array('event' => $event_id));
            if (!empty($tcont)) {
                $tabs[$name] = $tcont;
            }
        }
        EE_Registry::instance()->load_helper('Tabbed_Content');
        //we want this to be tabbed content so let's use the EEH_Tabbed_Content::display helper.
        $tabbed_content = EEH_Tabbed_Content::display($tabs);
        if (is_wp_error($tabbed_content)) {
            $tabbed_content = $tabbed_content->get_error_message();
        }
        $notices = '<div id="espresso-ajax-loading" class="ajax-loader-grey">
				<span class="ee-spinner ee-spin"></span><span class="hidden">' . __('loading...', 'event_espresso') . '</span>
			</div><div class="ee-notices"></div>';
        if (defined('DOING_AJAX')) {
            return $tabbed_content;
        }
        do_action('AHEE__espresso_events_Messages_Hooks_Extend__messages_metabox__before_content');
        echo $notices . '<div class="messages-tabs-content">' . $tabbed_content . '</div>';
        do_action('AHEE__espresso_events_Messages_Hooks_Extend__messages_metabox__after_content');
    }