Middle click to paste is an unrelated thing that drives me up the wall in Linux. Many of the programs I use on a daily basis have specific actions triggered by a middle click that I use often, but if I miss my target and hit a text area instead, it injects whatever I had in my clipboard into the text, often without me realizing it until later. (In one instance, my clipboard contents made it into an email I sent out. Thankfully, it was minor enough that it just looked like a typo, but it could have been much worse.)

Unfortunately, I'm not aware of any way to turn off this behavior.