Opponent let HIS time run out and claimed victory...

Now that this has happened to me, I wish the "Claim victory" feature didn't exist at all. If my opponent rage quits and leaves his tab open, I'm OK with waiting because at least I can do something else in the meantime. Now I have to stare at the screen ALL THE TIME in case he claims victory...
And no, I did not get notified that he made his move. Maybe it's just my browser.
Beware of this type of cheating everyone!!