good example - text fields in Mozilla work the same way as Win32 edit fields, and mostly the same way as edit fields on most Linux libraries.
So do the Mozilla coders choose to implement different functionality for a different platform, or do they make the application interface consistant across all platforms? If the answer is OS consistancy (rather than application consistancy), then we are back to square one of ont having a truely cross-platform library.
I don't know why you believe that "truely" cross-platform implies a uniform user experience on all platforms. Uniform user experience on all platforms tends to mean wrong user experience on all but possibly one, and users (at least Mac users, because they tends to have high expectations of their applications) reject this.
Put simply, in professional Mac development, developer convenience is secondary to user experience, and the market has shown time and again that Mac users are willing to pay for products that respect them. If you are designing a cross-platform framework, you have to understand this.
I do - which is why I say that a cross-platofrm GUI is extremely hard.
To answer your other question, I believe that a boost C++ GUI framework would gain adoption on Mac OS X _if_ it is designed with users, not developers, in mind -- which is precisely what I am trying to explain here.
If it is not designed primarly for developers, why would an OSX developer choose a C++ library over the more conventional C/O-C library? There would be no real incentive to switch to C++... And yes I do agree that it should be designed based around the user experience, and not necessarily around the developer... I'm trying to say is that for Win32 / Unix, you can get away with using C++ for developing GUI's, as this is the norm. For Mac, its not the norm, so why would a developer switch to C++, from say O-C... Mathew