Ask HN: What unusual limits or behaviours have you seen from browser vendors?

I build webapps and have noticed a few limitations and unusual behaviours in browsers, mainly Chrome and Safari. I tend to actively follow the relevant issues, and can think of at least two Chrome bugs/features that deliver some very minor benefits toward Google. I don't mean to attribute to malice what is almost certainly closer to incompetence, but thought it would be interesting to hear from HN participants about unusual browser limitations. For issues I've found, I've been surprised by how little known they are among web developers.