Hi, As I remember, Sandro was looking for some debugging utility library to instrument GEOS code with. I've just found something not mentioned yet in this discussion. It's DrC's Inline Debugger http://mysite.verizon.net/astronaut/drchipdbg/index.html Yet, another tool to consider. Cheers -- Mateusz Łoskot http://mateusz.loskot.net