In mailing list discussions, I've noticed that the practice of replying "+1" to messages with which one agrees has become very widespread.
I think this is interesting for a lot of reasons, such as what it shows about habits picked up in communicating via social network sites that grew out of e-mail percolating back to e-mail. We seem to have really grown to like this idea of "voting" for people's messages, and if there's no "Like" or "+1" button on their message, we'll make our own. (Likewise, apparently a person's name is no longer sufficient to indicate that one is addressing them in an e-mail -- am I right, @dear_reader?)
The problem for me is that I have my venerable awesome e-mail client Gnus set to hide quoted text in messages by default with
(add-hook 'gnus-article-prepare-hook (lambda () (gnus-article-hide-citation 1))), and it thinks that "+" is the start of a quoted line -- so it hides the "+1". While there's a certain poetic justice to that, it confuses me because it makes the message look empty, and someone could do something like "+1 I'm pregnant too", causing me to miss some very important news.
The fix for this is to change the regexp pattern Gnus uses to decide if a line is a message quote or not.
gnus-message-cite-prefix-regexp is built using
message-cite-prefix-regexp, so I changed the value of the latter, removing the literal "+". I also found while investigating this that I already configure that variable in order to add "#>" which someone sometime during my 9 years of using Gnus must have used. The net result is
(setq message-cite-prefix-regexp "\\([ ]*[-_.#[:word:]]+>+\\|[ ]*>|}]\\)+"). (Note that some of those whitespace characters are tabs, which probably won't display properly here, but you can compare to the default value to see what I actually changed).