When I had added the files from /root/.config/gconf/apps/dockbarx to my xfceaddons_yara_1.5.sfs those files where already there before anything from xfce, emerald, dockbarx etc. could have been executed. And it was loaded to a top layer. Though it didn't work that way.Problem solved: the program store her settings in gconf for reinstallation, and only it access at first boot, so your script must copy the /root/.config/gconf/apps/dockbarx directory from temp location BEFORE that first start. Changes after start are not ready by application.
However, when I tried to solve this by copying from temp location I had done this from 'autostart', so probably dockbarx has been executed once already.
Will give this another go, trying to include the code of to copy those files into a section that will be executed from /etc/profile.local - so, definitely before dockbarx could have been executed once.
Still got the version of xfceaddons_yara_1.5.sfs that includes dockbarx stuff to check this quickly (tonight).
Thanks.