This misses the point. I have plenty of 'phantom' unread messages which don't get displayed by the widget. I can post screen shots if you don't believe me...

The conversations application shows that I have loads of unread messages from certain contacts but there's no way of navigating them or even ascertaining which ones they are. I suspect that the IM ones are generated by being logged in in more than one place and recieving multiple messages in a short space of time. I'm not sure how the text message ones are generated; for some contacts I've opened every single message they've ever sent to me and I still have unread messages from them. Either there are hidden messages (bug) or the unread count implementation is buggy.

What I'd like is a simple option to "mark all messages as read"
or "mark all messages from this contact as read".