If a feature like this was implemented, I would want it to be compatible with Doxygen syntax, so that "intellisense" and generated documentation always showed exactly the same thing. It should work for undocumented code as well, of course, showing the class, function and variable names. It is often enough.
What bugs me a little about the way such intellisense features work in C::B, is that I often want to call functions that I have just created in another project, and that information hasn't been updated in the help system yet, so I am often left with no help (except looking up the header file manually). Perfectly understandable, but it limits the usability unless you develop against a stable library. Still I would not want C::B to use my computer resources to constantly rescan my code to fix this issue, so I am allright with how things are.