Attrui: handling/displaying as list?

I have a JSUI project where I want to present some attributes as a list but I can't figure out how it works. I've tried using the Display Mode setting for the attrui object in the Max inspector but it doesn't seem to do anything. I was wondering if there's something I have to do in my getter/setter functions for the attribute in order to present them in a drop-down list format in the same way you can set the Orientation attribute for an attrui object.