Question: Can software still be sold commercially that and be proprietary when parts of it are based on GPL code? Details: I am intending to sell software that I'm working on. My problem is some parts of the software (like the Look and Feel classes, etc) are based on GPL based (open source) software code. I have not modified the GPL code, I just use the API. The GPL appears to not address (at least as far as I can tell) use of an GPL API. Anyone out there ever tackle this question? Thanks in advance.