Some things that have prevented me from documenting these functions
The lock method has a mysterious light userdata return value. I have no idea what its use is on the Lua side. They also didn't seem to affect the performance of drawing operation in any measurable way, so I left them for later.
I have no idea why these are wrapped, my only guess is that rude got carried away, anyway, the 'mysterious' light user data is the lock pointer (which is stored internally as well and as such is not needed for unlock). As far as I can tell locking is only needed when you want raw memory access, because it is only used when it is copied to mem. --Bartbes 18:23, 31 March 2010 (UTC)
This sets the flag in the C++ particle system object, but this flag does not affect any calculations. I assume it is a feature that is meant to be implemented in the future, but is not done yet.
These don't seem to appear in CircleShape and PolygonShape, so I suspect they cannot be used yet. I might just have missed something.