Controlling what groups show in the group buffer

[Simon Kellett]

I am trying to fine tune my Gnus setup and have a few questions !!

I know that I can use "l" and "L" but can I fine tune what groups are
visible with the "l" (gnus-group-list-groups): specifically I would
like to have the option to only see those groups that have some
*unseen* articles.

Also could I set "l" to NOT show those groups with only marked
articles.

Ideally I would have a single key that would role around:
- all groups
- groups with some new and/or unseen articles
- groups with only unseen articles
- back to all groups

TIA, Simon

-- 
Gentoo Linux, Fvwm, Firefox        |            Xemacs, Vm, Gnus
Simon Kellett, Darmstadt, Germany  |  http://home.arcor.de/zoxed