[Pharo-project] Geometric model in Pharo

Hi! I'm actually doing my final-year internship in Thalès and I'm porting an application, for creating UI, from VisualWorks to Pharo (Using Athens :). The problem is they use a geometric model already implemented in VisualWorks (Graphics-Geometry package). The features which are very important to have is the possibility to convert a figure (like a Circle) to a Polyline representation. (They use it, for example, to know if the mouse are on a shape) That there is something in Pharo that I could use? Thanks! Tristan.