Mappet has a feature where you can create UI (User Interfaces) with JS scripts. There was an interesting suggested feature by Kirkus, which basically requests dialogue, inventory and pause screens to be customizable, which is where UI editor comes in.
UI editor allows to create a template for user interfaces, which can be displayed to the user, and handle logic by a script, without writing a single line of code.
Note: BBS isn’t a mod. BBS is a standalone application written in Java, which is designed to be a powerful sandbox for creating machinimas and maps/mini-games. If you’d like to try it out, feel free to join BBS’ Discord server: