[FigBug]

Supporting Carbon isn't really an option, it was a technology designed to ease porting from OS9 to OSX. It's been deprecated for years, is 32 bit only and is being dropped completely after macOS 10.14 Mojave.

I think it would make more sense to slowly port the Windows version to Qt. And then when that process is complete, you get a Mac and a Linux version.

[honeywhite]

Depends what you mean by Carbon. If you mean "the UI parts of HIToolbox", then yes, Carbon is deprecated. If you mean Carbon in general, most parts of it have been ported to x64, and you wouldn't call that deprecated.