In the 70s it was fashionable for people to stymy a discussant by saying, "I've said everything I have to say" and conveniently shutting up.

The most sensible retorts to that, of course, would have been:

--"Well, I haven't, but it looks as though you've decided to stop listening."

--"I have as much right to say when this discussion is over or not."

--"I only wish that everything you said made sense."

--"So what? That doesn't make you right." 

--"Looks to me like you're dying to say more."