introduce the notion of program, it might be the correct solution to the question on how to expose stuff to the user. Programs are basically in charge of transforming the parameters of the shape (wether it is dab or anything else) and of the coloring. Until then they were forced to appears as a list inside the dynamic brush, now they are independent, which means we can create more easily different type of programs and also more easily affects programs to differents shapes and coloring.