Hello, The following code seems to trigger the Persistance machinery. Is it true? ----------------------------- ## bounds: context, container, script, _, traverse_subpath ## parameters: background, image result = None if background == "": return "left:0px; top:0px" for name, object in container.getParentNode().objectItems(): if name == background: back_width = int(object.getProperty("width")) back_height = int(object.getProperty("height")) if name == image: front_width = int(object.getProperty("width")) front_height = int(object.getProperty("height")) left = (back_width - front_width) / 2 top = (back_height - front_height) /2 result = "left:" + str(left) + "px; top:" + str(top) + "px" return result ------------------------------ The reason I ask this question is that sometimes I get Conflict Error when this script is executed. It's the case when it's called many times in the same document. Cyril Elkaim