Right now I am working within Manta to load at run time scenes such as scene_0.dll, rather than compiling scene_0.cc into Manta at compile time. When that works the program I am developing that uses Manta will come next. The intention is to use Manta purely as Dlls rather than Libs, which would presumably sidestep the duplicated static variable problem I posted earlier. I think this would work because there would be no static linkage.

I see that either I stick __declspec(dllexport) to all classes.

Or, like you suggested, export the class Thread, which contains that static member threadids. Since Thread is part of the project Manta_Core and the desire is to get Manta_Core.dll, I would probably have to export all classes in this project?