Most public restrooms for men in the US have a row of urinals separated by a small wall shingle bolted to the wall. These are usually around shoulder height on me, so do not block vision sideways.
While at the movies last night, the man that came up to the urinal next to me was rather insistent about trying to strike up a conversation about the movie that he had just seen. At first I just ignored him, and when he persisted, I told him (Somewhat abruptly I admit) that I was not interested in a conversation. I believe my words were along the lines of "Look, I just don't want to talk to you right now", which got a rather snippy reaction from him.
How do you handle a stranger that wants to talk to you in a public restroom?