I run into this little annoying bug today, so here is a quick patch.
The "*" mapnik-reference symbolizer causes a section-* className to be created and then queried with jQuery selector, while * is a metacharacter for jQuery.
I'm not aware of some escape method in jQuery itself, hence some ad hoc solution seemed needed.
Thus, I've seen four solutions:
Having no overview of tilemill internal, I thought the last solution was enough, but I may be wrong. ;)
[ui] Fix "*" link not working in carto reference (see mapbox/tilemill…
thanks for the patch, will apply shortly.