Well, the chimera program can totally run on Windows; it just uses a particular DLL for a good chunk of it's runtime. That's not super different from, say, a C# app with some native Win32 code, right?
A couple of plausible scenarios:
1. You have a legacy UNIX app that is now only being used on Windows, but rewriting it entirely is a giant project. You can compile it against Cygwin, and then new development can run on Windows.
2. You have a cross-platform app that needs a few OS-specific things in certain places. Maybe it's some sort of system status checking/auditing tool, maybe it interacts with hardware drivers, etc. You can use #ifdef WIN32 and call Windows-specific APIs, just like you can use #ifdefs to check for Apple-specific or Linux-specific APIs, and you don't have to port your entire app away from the UNIX model.
A couple of plausible scenarios:
1. You have a legacy UNIX app that is now only being used on Windows, but rewriting it entirely is a giant project. You can compile it against Cygwin, and then new development can run on Windows.
2. You have a cross-platform app that needs a few OS-specific things in certain places. Maybe it's some sort of system status checking/auditing tool, maybe it interacts with hardware drivers, etc. You can use #ifdef WIN32 and call Windows-specific APIs, just like you can use #ifdefs to check for Apple-specific or Linux-specific APIs, and you don't have to port your entire app away from the UNIX model.