I have just switched to the new Xfce 4.10 after a long break from using it (had Gnome 2, but Gnome project "died", at least for me).
I've noticed that my preferred keyboard layout is not present on the Xfce keyboard settings list, however it is functioning normally when loaded using setxkbmap. I think that this is not an Xfce issue per se but rather with some of its dependencies (libxklavier perhaps?). I've noticed also a bug, under my language a keyboard from a different country is present, which shouldn't naturally be there.
I can write a patch if someone would direct me where to look.