Hello,

> Sorry if I was not clear. The first problem I reported appears on a
> Xfree 4.5 from xsrc. In a second time, I try to use Xorg from pkgsrc (
> to see if they are some improvement on kbd by chance ) but I expected
> the second problem. Don't bother yourself with the second problem : I
> don't really want to use xorg, just want to see if it solves my first
> problem.

Ok.
I have a 2004 iBook G4 too, although the keyboard is 'international' -
more or less US layout - and I don't have any dead keys. 
So - which keys are affected? Does anything change when you use 
Option "XkbModel"   "pc105"
instead? ( make sure you stick to the 'kbd' driver, 'keyboard' has
lots of weird problems with non-PC keyboards ) Yes, that's a blatant lie
but XFree translates everything to PCish scancodes anyway before feeding
it to xkb so the PC keymaps should just work. 

have fun
Michael