National Conventions and Protesting

I realize that there will be people protesting issues at both national conventions, but are there people who are going to be protesting the conventions themselves? Meaning that they think that having the conventions is wrong. I suppose Iā€™m asking if this has happened before, rather than expecting you to tell the future :stuck_out_tongue:

and I mean the sign carrying kind, not pissed off Boston travelers who merely complain(with good reason) about how the convention will make it hard to get around.