问如何在自定义侧边栏菜单上突出显示当前子页面？

EN

 <?php

                /* if the current pages has a parent, i.e. we are on a subpage */
                if($post->post_parent){
                    /* $children = wp_list_pages("title_li=&include=".$post->post_parent."&echo=0"); // list the parent page */
                    $children .= wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0"); // append the list of children pages to the same $children variable
                }

                /* else if the current page does not have a parent, i.e. this is a top level page */
                else {
                    //$children = wp_list_pages("title_li=&include=".$post->ID."&echo=0");    // include the parent page as well
                    $children .= wp_list_pages("title_li=&child_of=".$post->ID."&echo=0&");   // form a list of the children of the current page
                }

                /* if we ended up with any pages from the queries above */
                if ($children) { ?>
            <ul class="submenu">
                <?php echo $children; /*print list of pages*/ ?>
            </ul>
            <?php } ?>