Hi Steve, In the zclass definition I have a bunch of Image objects together with the following script. SCRIPT s_center(width, height, image): import string result = None for item in container.objectItems(): if string.strip(item[0]) == image: image_width = int(item[1].getProperty("width")) image_height = int(item[1].getProperty("height")) left = (int(width) - image_width) / 2 top = (int(height) - image_height) /2 result = "left:" + str(left) + "px; top:" + str(top) + "px" return result /END_SCRIPT This script works fine if I test it inside the test tabs of the zclass. But if I run it from an instance 'container.objectItems()' returns nothing. I understand why but my problem is how to get access of the images from the instance. What I need is something giving a reference to the zclass definition from one of its instance. I think I can use the DOM model and walk through until I find it but it should be better to have a direct access from the instance itself, wrong? Thanks, Cyril