I've already raised this once on the ML [1]. 

X.Org and XKB limit in a hardcoded manner the number of configured keyboard layouts to four [2]. It would be nice if xfce4-xkb could work around such a limitation. A related discussion [3].

On Fri, Mar 27, 2009 at 1:05 PM, Alexander Iliev <sasoiliev@mamul.org> wrote:
> Some time ago I was planning to add such a feature in xfce4-xkb plugin,
> but the code would get really messy with such a feature. I might take
> a look into this again.
>


[1] http://old.nabble.com/number-of-configured-keyboard-layouts-tt22739479.html#a22739479
[2] http://bugs.freedesktop.org/show_bug.cgi?id=19501
[3] http://community.livejournal.com/xkbconfig/304.html