The versions are not too independent from each other. You can bet that 90+% of the code is the same set of classes shared by mac and windows. The only differences would be in the classes that handle truly OS-specific stuff. Most application programming can be done in a fairly generalized, platform-independent way, then compiled separately for each platform. The different versions are really made at the linking and compiling level, rather than at the source code level. For the OS X and OS 9 versions... they're even less different. The OS 9 version is probably the OS X version tweaked to use carbonLib. The bugs we're seeing may just be an oversight, like a piece of code that works in OS X but didn't translate well in 9. I'd like to think Carrara 2.1 irons this out, now that it's been brought to light. -Adam