In addition, it is also now quite easy to customize the groups via the trac.ini file. For example:
{{{
[milestone-groups]
closed = closed
closed.order = 0
closed.query_args = group=resolution
closed.overall_completion = true
active = *
active.order = 1
active.css_class = open
new = new,reopened
new.order = 2
}}}
