User interfaces are evolving beyond bitmaps to include animation and special effects that utilize powerful graphics hardware. Unfortunately, the APIs used to implement these features are often not programmer friendly and can result in verbose code that is written in multiple languages. This paper describes our experience in improving UI library usability through lightweight domain speciﬁc languages (DSL) that are limited in scope to ease the use of library features rather than whole libraries. Lightweight DSL code is evaluated without meta-programming by using a hosting language’s conventional extensibility mechanisms such as operating overloading and automatic conversions. As a result, lightweight DSLs are easy to implement while their code can easily be modularized and manipulated by host language abstractions. We demonstrate the effectiveness of our technique through two C# lightweight DSLs for expressing databinding and pixel shading in Microsoft’s WPF UI library.