There are ones that don't (Quassel for example) and there are ones that do (VLC for one). At the end there is always some polish a developer needs to do, no mat

There are ones that don't (Quassel for example) and there are ones that do (VLC for one). At the end there is always some polish a developer needs to do, no matter how awesome the toolkit gets. If the developer won't do that, your app will look crap. And its not just OSX, you write your Qt app on Windows and then you run it on Linux, you will need some fine tuning to look perfect. I still prefer it over any other free IRC client for OSX simply because the feature set rocks.