Hi Hoang,
I'm afraid your code:
items[0].properties = customObject;
only *seems* to work, but actually does not. The properties property is a special command that only deals with native, valid, properties of a DOM object. Used as a setter, it simply ignores non-native keys. Used as a getter, it simply returns available properties. More generally, given a page item—say myRectangle— any statement such as myRectangle.myCustomProperty = "foobar" will cause an error ("Invalid property or method", or whatever) because you cannot extend DOM object instances. They all are command wrappers (=specifiers) and don't work as regular JS objects.
Anyway, you can extend the methods of DOM object prototypes, e.g.:
Rectangle.prototype.myCustomMethod = function(){ return this.label;};
When you do that, keep in mind that a Rectangle object instance can reflect several actual InDesign rectangles. For example, myDoc.rectangles.everyItem() is seen as a Rectangle (in terms of cast).
IMHO, the right way to attach custom properties to DOM components is to use insertLabel() / extractLabel() with serialized objects.
@+
Marc
EDIT: The CSAWLib bug you mention is not connected to the problem of setting custom properties.
