Willing to be able to develop my own tools if needed, I decided to learn the Qt C++ library, a UI oriented lib. Learning by reading, trying and testing features is interesting but doing it with a goal makes it even more exciting. That's why I decided to created a little editor prototype based on "mental maps". That's how this GDD editor was created, of course it is really basic and not production ready but coding it made me understand better some limits of my mental maps concept by tweeking it in many ways. It also fulfilled the first intented goal too : learning how to code external tools which would be useful to a designer and get some experience in software architecture! NB: Only openable with Qt Creator for now.