Login to http://zh.wikipedia.org/ and stare at the screen for a few seconds. Wait, it is probably due to me User:Jidanni being a member of some club. Anyway, there is no way for a normal user to file a proper bug report about it, as it is all hidden in javascript that he does not see. I'll contact some of those club members about this problem.
Note that maybe their browsers have a wide enough screen so the line counts of the messages are the same so they don't notice the problem.