Hi there! I think it's very convenient to cycle through windows in a group. So I made a quick patch to demonstrate this feature [1]. If you think it's nice and useful, I can rewrite client_cycleingroup() to use a flag for client_cycle(), make documentation and so.
[1] http://plhk.ru/static/misc/cwm-cycle-in-a-group.diff -- Alexander Polakov | plhk.ru