Maybe this is a weird bug related to my C::B version.
I've played with -fs a lot, but nothing change, Also I changed xterm with another T.E's (mlterm, aterm, etc) but always a xterm (that infamous little one) is launched (from within the others T.E.'s)
Next week I will give a try to a more recent nightly build. I will keep you informed.
Thanks a lot.