One "feature" that bugs the hell out of me is the automatic conversion of >'s in mail and news replies to vertical gray bars. This wreaks havoc in the Python newsgroup, for example, where some session code like this...
>>> spam = "asdf" >>> 1 + 2 3 >>> looks more like this... ||| spam = "asdf" ||| 1 + 2 3 ||| Except with really ugly gray vertical lines. It's not just for this Python newsgroup, either. I just don't like the bars period. This really needs to be an option to turn off. If you can turn it off somewhere, I haven't found the option yet. Luke