I believe I’ve finished patching up SDL to work correctly with retina screens. (That is, a single build works correctly on retina systems and also on non-retina systems). I’ll be sending the patch to the fine SDL maintainers tomorrow, and we’ll see what issues they notice with it.
I’ll also look at putting together an updated Testbeds build for OS X, so people can see what needs to be done to make retina support work. The changes are all in the SDL library and in the final build packaging; there are no changes to the VectorStorm library itself. So hopefully it shouldn’t be much of a drama.