Indeed, it is built in Pharo. However, the UI is designed as a language made of visual and interactive operators that can be programmed and combined in many way

Indeed, it is built in Pharo. However, the UI is designed as a language made of visual and interactive operators that can be programmed and combined in many ways live. This enables a new kind of programming we call moldable development through which we construct tools for each individual development problem. In any case, I'd be very happy to support you in playing with GT. Please ping us on Twitter (https://twitter.com/feenkcom https://twitter.com/feenkcom) or via email.