Wouldn't "Mark all read" better name for it?

TiGR

Just because this naming is more common. Don't you think so?

Linc

"Thread" is the more common naming convention, yet Vanilla called them "Discussions". More common doesn't necessarily mean more sensible.

I chose to call it 'Viewed' because A) That's what the rest of the application refers to - "views" - and Software can't really tell whether you've "read" something anyway, only whether you've viewed it.

"Viewed" isn't more common but seemed the more sensible label. Of course you're welcome to change the button label on your install.