At the moment, the chat window doesn't alert the user in any way that another user has instigated a chat with them. The person receiving the message won't know they have gotten a message unless they: 1. already have their chat window open or 2. randomly click on their bubble. This was mentioned in the forum post http://collabtive.o-dyn.de/forum/viewtopic.php?f=8&t=7274 - it's a bigger issue then you would think because it renders the chat useless, especially while actively working - if I am programming I don't want to have to open the chat up every minute to see if I have received a message. Even if you leave the chat window open and minimized you don't get any sounds to alert you / popup boxes.
So I guess I am requesting that the chat some kind of alert notification added so that I know if a user is trying to instigate a chat with me ( unless there is already a solution to this that I don't know about ??)