Try Pushbullet. I use it on my forum.
Also search here for pushbullet, there are a number of threads for it.
If someone chats you and you haven't viewed it yet, would be cool to have it flash in the title bar in case you're in another tab. Back and forth between Chat from User and the actual title of the page you're on.
Oh wtf this already happens.
Fuck I'm retarded.
Theres no notifications, only shows the lasts chats. but when someone talkto you not appears notification in that menu.
As far as I know, that menu doesn't show unread chats, so that's working as it should.
On mobile theres any menú to see chats