Re: Multi-tasking..as a matter of interest..
..have any of you down voters actually shipped any commercial cross-platform and / or MacOSX shrikwrap?
In my case shipped first commercial MacOS product in 1985. Shipped last commercial product on platform a few years ago. Only 600k plus activations, all platforms, worldwide in first three months. As for NextStep, tried to bum a ticket for the launch in '89, I was user number three of Interface Builder so I knew people. Did platform product viability projects for NS 1.0, 2.0 and 3.0. None made the cut. Only 60K units ever sold. No market. Quite separate from the technical problems. Like the Mach kernel calls never working properly. So they are now mapped to pthread wrappers. Or every dot release breaking the SCSI driver. And I know the real story of the Darwin fiasco.
So to someone trying to get product out the door, and has been doing it for decades, MacOS X is just a swamp. With every .n release breaking something important. Just like in the NS days. MacOS 8.x and before was fairly benign. Stuff worked. So its QT all the way for the very very occasional MacOSX project that come up nowadays. Always cross platform. The unit market share is about what it was 25 years ago. And the software market share is far less than half of what it was back then
Oh well. The first 10 years or so were fun. While it lasted.