Another thumbs-up for Qt here. I wasn't too sure about the framework when I first started playing with it, but I've gotta admit I've been sold on it since. Signals & Slots works surprisingly well, and it pretty much has all the features you really need for either apps or desktop programs. What I really like, though, is that it feels a lot more open than other APIs; while you can do everything in the Qt way (and thereby leverage their massive infrastructure), you can also just choose to write any old C/C++ code and add it into your app. Not long ago I needed to run an external process from my app, and rather than bothering to learn how Qt would do it, I just dumped a good old fork()/exec() into my code. And the app worked perfectly fine! (Of course, this means the app only works in Linux. If I do want to port that app to other platforms, I'll probably go ahead and figure out how to do it the Qt way in the future...)