The GEC Toolkit offers to programmers a high-level, generic style of programming Graphical User Interfaces (GUIs). Programmers are not concerned with low-level widget plumbing. Instead, they use mathematical data models that reflect both the application logic and the visualisation. The data models and the logic are expressed as standard functional style data types and functions over these data types. This significantly brings down the learning effort. In this paper we present an improved programming method of this toolkit and illustrate it by means of a complicated case study: that of a family tree editor. The new programming method brings GUI programming into the reach of every novice functional programmer.