If you comment something on Stack Overflow, you need to enter at least 15 characters, and you can't post a comment which just contain spaces.
But if you type in zero-width spaces it will work. A zero-width space can be translated with ​ in HTML.
For better understanding, I have added a zero-width space comment to my question.
There are many work-arounds for certain limitations. Sometimes we fix them, and sometimes we say "meh". If the restriction prevents a couple of "Ok." comments, it has fulfilled its purpose.
Back when I didn't work for Stack Exchange (or Stack Overflow, as it was called), I reported something similar, and found Jeff Atwood's reply boring. But he really was right. When you allow users to post stuff, there's always going to be someone who uses the magic of Unicode to do smart and/or funny stuff.
As long as it's something that can be looked over (like one in a million comments apparently getting around the character limit), that's fine. If it happens too much, we'll prevent it, but it'll always be a game of cat and mouse – sooner or later someone finds something else.
And if someone starts doing actually harmful stuff – well, then the answer is "don't do that". It's abuse. Abuse isn't tolerated and will be handled.
- to fill the missing spaces since the backtick trick was blocked. Once you block that, I'll start using characters: aaaaa. Once you block that, heck, there's Lorem Ipsum. I'm not doing this because I'm keen on defying you guys - it's just that sometimes a "yes" is the perfectly natural thing to say in a conversation (however much you hate conversations in comments, they still sometimes happen), and I don't see the point in an arbitrary system limit forcing me to change the way I communicate.
...? @Jeff you can match this character with \u200b in regex.
There is an argument, pace Jeff, that these tricks are a good thing. Sometimes, a very short answer or comment is, really, truly, all there is to be said. The tricks are a bit like a privilege: people who know enough to know them can get around the limit. If the team stomps on them (and I could suggest some coding techniques involving ICU4J), then some consideration might be given to allowing short strings over some rep privilege limit.
