But you won't get a warning for writing posts that don't hit the mark. The post will literally be refused by the server, and it will kick you back into the editing screen.

Last time there was a character counter (200 minimum forum-wide, by the way... and something like seven years ago) it showed a little display under the editing box, but it was only in full-reply mode that it did. I don't know if there's a way I can make it show in the quick reply screen.