Well yes, because unless I'm much mistaken, Qt and GTk are both supported by OS X so they are both supersets. (This is obviously ignoring Windows, which is also

Well yes, because unless I'm much mistaken, Qt and GTk are both supported by OS X so they are both supersets. (This is obviously ignoring Windows, which is also supported by Qt and GTk but is probably difficult for other reasons.) There are also cross-platfrom native options like wxWidgets. These also work both on Linux and other systems. Finally, the last StackOverflow survey[1], which I think is pretty representative of the sort of people who would use a program like this, had both Linux and OS X at about the same level (~20% each). So Linux is certainly not negligible. [1]: https://www.surveymonkey.com/sr.aspx?sm=2RYrV_2bFw2aZ2RfedWHNW_2f0DgNnatyQnvvrorWEYhuAQ_3d https://www.surveymonkey.com/sr.aspx?sm=2RYrV_2bFw2aZ2RfedWH...