Complex systems often integrate domain-specific languages to let users customize the behavior. Developing tooling for such languages is typically time-consuming and error-prone. We present Jatte, a tool intended to simplify this development. Jatte works as a generic tree editor for an abstract syntax, but uses aspects and attribute grammars to support powerful modular ways of tuning both the projected view and the editing commands. We present the key features of Jatte, and discuss its application in an orchestration language for internet of things.