The Lit Window Library is a C++ library which provides "reflections" (extended runtime type information), adds "rules" to the "methods, properties, events" GUI coding paradigm, and contains a collection of frequent UI patterns. The goal of this library is to speed up GUI coding by a factor of 10. It does so by greatly reducing the amount of source code necessary to implement common, day-to-day user interface requirements. This is not just another "better widgets" library. The library introduces two new, different concepts to UI coding: a data abstraction layer (reflections) and rule-based programming.