[dwm] Full screen annoyance

Hello,

I switched from wmii to dwm since ~ 3 weeks and I really like it.
Thanks a lot for this great wm!

However, I am suffering from one little annoyance : both in floating
or tiled mode xterm never is full screen (even after a Mod+M. I have
to manually resize the window)
I guess it's probably it's probably not dwm's fault and that's a
stupid thing to fix but I can't find how. Any idea?

Thanks,

-- 
Simon Rozet <simon_AT_rozet.name>