Function: Incoming message ticker (like "The Bat")

I’ve been wondering why there’s no “incoming message banner” like Ritlabs “The Bat” is using. It is like some “ticker” floating anywhere over any other window showing up the “about” of an incoming message. To me it seems very handy and gives me a quick info about the incoming messages - so I can decide to show (or not) the complete mail by simply cklicking onto the message in the banner…