Getting further information from describe-function

[Deniz Dogan]

Hi, developers

I would like to write a little function which acts like the
completing-read of describe-function but the completion buffer should
use customizable faces which indicate whether what is completed to are
obsolote, macros, etc. One could even imagine using customizable
format strings for the output, possibly to be able to indicate e.g.
where the functions are defined. describe-function in its current
state is rather "dumb", simply using completing-read over obarray on
symbols that "are fboundp".

So to write this feature I had in mind...where do I start?

Thanks,
Deniz Dogan