I don't know whether this is the best solution, but it works for me.
I noticed that it `device-color-cells' returns 256 even though I've
got 24 bit color depth, but frankly, I don't care since I'm using my
own text-only toolbar anyway ;-)

Greetings

-- 
Michael Piotrowski, M.A.                               <mxp@dynalabs.de>
Public key at <http://www.dynalabs.de/mxp/pubkey.txt>