Adding parameters to user group line format functions?

["Johann 'Myrkraverk' Oskarsson" <myrkraverk@gmx.com>]

Hi all,

Is it hard to add a "list of useful things" to be passed to user format
functions for the group line?

In particular, I'd like to use my own group name `mangling' in
gnus-group-line-format with %uG but have no idea how my
gnus-user-format-function-G would get a hold of the current group,
server names and perhaps the backend method.

For a concrete example, I'd like to prefix news.eternal-september.org
groups with ES: and not news.eternal-september.org.  If the function
recieves the server (and group) name as a parameter I can simply use
assq for it.

The currenty documentation mentions the function will get a dummy
parameter, so adding a real information there should not affect
backwards compatibility, right?


Johann