Totally fictional situation (no, that didn't happen to me a while ago, just came into my mind.. ;)):
- user tries to click BudgetLightForum.com link on the top of front page
- browser finishes rendering the screen and decides to move the page up a bit (back to earlier position)
- click hits the Mark All Read - user is unhappy
A simple "Are you sure you want to mark all as read? Yes [No]" would help a lot. (Or a confirmation similar to mark as spam has..)
Uhm, I use that button very often (including on my phone) and actually would prefer not to have the need for a second click…
But that’s just my opinion.