w32 stack sniffing/unwinding and backtrace improvement

[LRN]

Which unwinder and sniffers are responsible for w32 stack unwinding 
(like, when printing a frame info or a backtrace)?
I have an idea to fetch the function address from the stack as a struct 
_EXCEPTION_RECORD, but i need to find the code that parses the frame. If 
i succeed, it will allow for more complete backtrace in cases where gdb 
is used as a JIT (in MS sense of that acronym) debugger and attaches to 
a process that had its stack already mangled by the OS exception handler.