I don't seem to have many confrontations - maybe it is because it is not worth my time, or maybe because I am 6'4" 220lb a lot of people tend to avoid it.
However, there was one, many years ago (geeze, 10 - 12 years ago). We had camped out in the Tomorrowland Terrace to watch the fireworks (long before there was a dessert party there). A bunch of other people had the same idea. In the spirit of Disney, the 5 or 6 totally unrelated families there arranged it so it was adults in the back, kids on the ground in front, and nobody at the railing, so that all could see. Other families would come up, see the open railing, stand by it, then notice what was going on and join the plan. It was great. Everyone was comfortable, and had a great view.
The show started, and 2 minutes in, a husband and wife with three kids walked up and stood at the railing. Somone explained to them (nicey) that they were blocking the view of about 25 people, and they were more than welcome to join everone else. The husband went to move with the kids and the wife said something along the lines of "That's their own fault for sitting back there, don't you move, we are standing here". The whole thing pretty much escalated. Every adult in the back was complaining to the woman (some made some really rude comments). The poor husband looked like he wanted to crawl into a hole and die - and the woman stool there steadfast - right in the middle. When it was over she turned around and said something like "I hope you are happy, you ruined the fireworks for my family"
-dave