Join The Team
For some reason, coding small and efficient window managers is not a very big hit these days. Using them, perhaps. Developing and maintaining them, not so much.
The team behind Blackbox has always been very small. BradleyHughes, its creator, has always been around, thankfully. There have also been people like JeffRaven and SeanPerry who donated a big chunk of their personal time and helped Blackbox advance. Finally, there's the faithful BlackboxCommunity who contribute patches, bug reports and testing and, naturally, styles.
If you can code C++, we can use you. You can start by simply reading the code. It's very clean, even people who are barely articulate at C++ can understand it and have been known to even create patches.
Further information regarding hands-on Blackbox coding can be found in the HackingGuide.