Suggestion - "Mark As Unread"

Not sure if this is already a feature or not. If it is, then I've missed out big time.

I've found that sometimes, it gets a bit too late in the evening for me to begin a conversation with members/guest/listeners who've just sent me a PMbut I would still like to read their message to know what they said at the time without me forgetting to respond the next day.

It'd be cool if there was just another little button next to the name of the person you're talking to (like the x button to hide conversations) but when clicked, it just makes the box highlighted green as if you've just got the message, and acts as a reminder to respond. When you next click on the box, the green will go away until you click it again.

- Leon