set_window_below, maximized window and gnome 3.8

[truen...@gmail.com]

I used the set_window_below() command with gnome 3.6 and was happy with it, but since upgrading to gnome 3.8, I have this strange bug : if the window is maximized before launching devilspie, I'm not able to see it anymore, it just turns gray, but I can still see its thumbnail when clicking gnome's "activities".

If I launch devilspie2 and then maximize the window, it works fine.

My complete script is :
if (get_application_name()=="VirtualBox") then
undecorate_window();
set_window_below();
end

Does anybody has an idea how to fix this ?