rrwood asks: "I'm starting work on what is more or less an open-source 3D modeling application, and I'd like to make it as cross-platform as possible (Linux, FreeBSD, Windows, MacOS, etc.). OpenGL takes care of the 3D rendering I'm going to need, but I also need some sort of widget set, and I'm looking for advice as to what to use in that regard. I've done my Google homework and have come up with the following, but would like feedback from anyone who has already used any of these, or has recommendations about anything I may have missed. Yes, I know about Blender, and be reassured I am not planning on reinventing that wheel, okay? :-) So, here's what I've found so far. As I said, if anyone can add to this list or share his/her experiences actually working with any of these, that would be greatly appreciated."