Nevermind. Turns out the thread I was trying to reply to was locked and I didn't notice because the icon didn't draw me to it. Perhaps removing the “reply” link from locked threads (or putting “thread is locked” somewhere) would be a good UI improvement to these boards?
Also there is no mouseover popup to explain icons, nor is there an icon legend anywhere (as far as I can see; although I haven't looked very hard) to explain what the icons mean. Can we get something like that?
Edited Lyle Waldman (Dec. 12, 2012 06:08:12 PM)