lua_pushusertag and object ownership?

[lemkef@...]

So far Lua's looking like the best solution for any of my scripting 
problems.  MUCH easier to implement that Python, and faster from what 
I hear.  One problem though.

I can't seem to find any information regarding ownership when using 
the lua_pushusertag C function.  Who owns the other objects (strings 
and such) is pretty clearly defined, but I can't find anything 
relevant.

My question:  When I use lua_pushusertag to call a lua-function with 
a pointer to a C++ object, do I have to increment a reference count 
so that lua doesn't garbage collect it on me?  And when I have an 
object in Lua that returns a pointer to a C++ object, will Lua still 
own that object also?

If it helps, I'm using 3.2, and tolua.

Thanks!,

Fabian