/* Iterate through the children of an object (start from the "oldest")  */
lv_obj_t* lv_obj_get_child_back(const lv_obj_t *obj, const lv_obj_t *child)
/* Iterate through the children of an object (start from the "oldest")  */
lv_obj_t* lv_obj_get_child_back(const lv_obj_t *obj, const lv_obj_t *child)
{
    if(child == NULL) {
        return lv_ll_get_tail(&obj->child_ll);
    } else {
        return lv_ll_get_prev(&obj->child_ll, child);
    }
    return NULL;
}