[dwm] how to detect activity in non-visible tags

Hi,
I usually have gaim tagged with a specific tag plus a rule to put it
in the float layer.
80% of the time it's in an invisible tag.

How can I detect that a new client window shows up in this invisible
tag? The idea is to detect the change and notify it in the status bar.

It seems applications like gaim uses the URGENT hint in such cases.

Any plan to do somethin with this hint? Are there any 3rd party
software to detect this in a shell script or something?

IM it's not the only situation I've found this issue (but is the
shorter to explain)

I guess I can add some rule to send this new popup windows to all
tags, but I don't want windows showing up in my face, just a small
message in my status bar.

thanks,

-- 
Julián