Right-click? Which mac osx version are you using? Are you using the Tiger's magicmouse or something? Anyway, it's not a chat room per se. You're sending a chat message directly to the host. It's a one on one chat scenario. No there's no warning or beeps or honks or lights flashing. The chat feature on LW is quite basic. It hasn't been updated since it was introduced. If you receive one, a chat window will open in front of you. Identical to when you send someone else a chat message. So you can only hope they're in front of their computer at that time. If not, chat tends to time out after a certain amount of time (I don't have a clue how long it takes. Perhaps an hour for it to time out. And I'm only guessing it times out.) So anyway, it works both ways, they'll receive a popup chat window if they receive a message.

You might only succeed in getting one in 5 or 10 people to respond to chats. They may have left LW running whilst they're away at work or asleep, etc.