Great idea. Important for me: C++ (also in the files accessing MUI) and libcurl for easier http(s) access. The SDK should also contain (cross-)compiler for and on all platforms, so that you can compile on every platform for every platform. E.g. I do not have an AOS4 machine and my OS3 version does not work on OS4 (problems with libcurl). Normally I'm conding under MorphOS, but there is no working debugger, so I also have to code under OS3.