I have the option 'Mark read on view article' enabled, yet to mark an article as read by viewing it, I have to look at it twice. If I'm highlighting the message before it is read, when the message is download and I can read it, it isn't being marked as read. I have to move off of the message and back onto it before it's marked as read.
The same hold true if I double-click an article to open it. Once isn't enough. I have to open it, close it, then open it again.