With this commit, it is possible to provide a list of formats for the

clock module. You can cycle through these different formats with the
mousewheel. It is backward compatible but if you want to exploit the feature, you need to define format as a list of format such as :
status.register("clock",
    format=[
       "%a %-d %b %X KW%V",
       "%a %-d %b %X "
        ],
    )

I was thinking of passing a list of tuples in order to be able to pass different timezones.
PEP 8 / consistency please (i.e. current_format_id)