BaseElements Plugin is required for all FileMaker Pro 12 users, mac and PC. It is free and open source and available here. Follow the instructions on the web site on how to download it and install it. You need version 2.2 or greater.
BaseElements plugin provides the Base64 encoding and decoding functionality that is missing on FileMaker 12.
Reactor is no longer required as of GoDraw v2.0.2