I have missed so many messages/conversations because of inadequate notification.

Please make the new message notification persistent until all new messages have been read. Also use a more eye-catching icon for unread messages. Maybe different styles for different notification levels.

It would be great if you could make a flashing task-bar thing as well. It should be a minimized HipChat window which, once clicked would open the latest message. Could be a setting to switch on in "Settings".