$menu_control .= '<select style="'. $style .'" name="penci_cat_mega_menu[' . $item->ID . ']" id="" class="widefat code edit-menu-item-url">';
        foreach ( $td_category_tree as $category => $category_id ) {
            $menu_control .= '<option value="' . $category_id . '"' . selected( $penci_cat_mega_menu, $category_id, false ) . '>' . $category . '</option>';
        }

function penci_wp_update_nav_menu_item( $menu_id, $menu_item_id, $args ) {

    // Update meta menu items
    if ( isset( $_POST['penci_cat_mega_menu'][$menu_item_id] ) ) {
        update_post_meta( $menu_item_id, 'penci_cat_mega_menu', $_POST['penci_cat_mega_menu'][$menu_item_id] );
    }
    if ( isset( $_POST['penci_number_mega_menu'][$menu_item_id] ) ) {
        update_post_meta( $menu_item_id, 'penci_number_mega_menu', $_POST['penci_number_mega_menu'][$menu_item_id] );
    }

}

function hook_wp_nav_menu_objects( $items, $args = '' ) {
    $menu_items = array();

    foreach ( $items as &$item ) {
        $item->is_mega_menu = false;

        // if menu is mega menu, render mega menu
        $penci_catid_mega_menu = get_post_meta( $item->ID, 'penci_cat_mega_menu', true );
        $penci_number_mega_menu = get_post_meta( $item->ID, 'penci_number_mega_menu', true );
        if( ! isset( $penci_number_mega_menu ) || empty ( $penci_number_mega_menu ) ): $penci_number_mega_menu = '1';  endif;

        if ( ! empty( $penci_catid_mega_menu ) ) {

            $item->classes[] = 'penci-mega-menu';

            // add the parent menu
            $menu_items[] = $item;

            // create mega menu item
            $post                 = new stdClass;
            $post->ID             = 0;
            $post->post_author    = '';
            $post->post_date      = '';
            $post->post_date_gmt  = '';
            $post->post_password  = '';
            $post->post_type      = 'menu_penci';
            $post->post_status    = 'draft';
            $post->to_ping        = '';
            $post->pinged         = '';
            $post->comment_status = get_option( 'default_comment_status' );
            $post->ping_status    = get_option( 'default_ping_status' );
            $post->post_pingback  = get_option( 'default_pingback_flag' );
            $post->post_category  = get_option( 'default_category' );
            $post->page_template  = 'default';
            $post->post_parent    = 0;
            $post->menu_order     = 0;
            $new_item             = new WP_Post( $post );

            /*
             * if this is mega menu
             * set the is_mega_menu flag
             * render content of this mega menu
             */
            $new_item->is_mega_menu = true; // sent to the menu walkers

            $new_item->menu_item_parent = $item->ID;

            $new_item->url   = '';
            $new_item->title = '';
            $new_item->title .= '<div class="penci-megamenu">';
            $new_item->title .= penci_return_html_mega_menu( $penci_catid_mega_menu, $penci_number_mega_menu );
            $new_item->title .= '</div>';

            $menu_items[] = $new_item;

        }
        else {
            $menu_items[] = $item;
        }
    } //end foreach