/usr/share/themes/Xfce/ is in gtk2-engines-xfce 2.8.1-3.
This file is owned by root:root, with mode 0o755.
..
/usr/share/themes/Xfce-4.0/gtk-2.0/
/usr/share/themes/Xfce-4.0/gtk-2.0/gtkrc
/usr/share/themes/Xfce-4.2/gtk-2.0/
/usr/share/themes/Xfce-4.2/gtk-2.0/gtkrc
/usr/share/themes/Xfce-4.4/gtk-2.0/
/usr/share/themes/Xfce-4.4/gtk-2.0/gtkrc
/usr/share/themes/Xfce-4.6/gtk-2.0/
/usr/share/themes/Xfce-4.6/gtk-2.0/gtkrc
/usr/share/themes/Xfce-b5/gtk-2.0/
/usr/share/themes/Xfce-b5/gtk-2.0/gtkrc
/usr/share/themes/Xfce-basic/gtk-2.0/
/usr/share/themes/Xfce-basic/gtk-2.0/gtkrc
/usr/share/themes/Xfce-cadmium/gtk-2.0/
/usr/share/themes/Xfce-cadmium/gtk-2.0/gtkrc
/usr/share/themes/Xfce-curve/gtk-2.0/
/usr/share/themes/Xfce-curve/gtk-2.0/gtkrc
/usr/share/themes/Xfce-dawn/gtk-2.0/
/usr/share/themes/Xfce-dawn/gtk-2.0/gtkrc
/usr/share/themes/Xfce-dusk/gtk-2.0/
/usr/share/themes/Xfce-dusk/gtk-2.0/gtkrc
/usr/share/themes/Xfce-kde2/gtk-2.0/
/usr/share/themes/Xfce-kde2/gtk-2.0/gtkrc
/usr/share/themes/Xfce-kolors/gtk-2.0/
/usr/share/themes/Xfce-kolors/gtk-2.0/gtkrc
/usr/share/themes/Xfce-light/gtk-2.0/
/usr/share/themes/Xfce-light/gtk-2.0/gtkrc
/usr/share/themes/Xfce-orange/gtk-2.0/
/usr/share/themes/Xfce-orange/gtk-2.0/gtkrc
/usr/share/themes/Xfce-redmondxp/gtk-2.0/
/usr/share/themes/Xfce-redmondxp/gtk-2.0/gtkrc
/usr/share/themes/Xfce-saltlake/gtk-2.0/
/usr/share/themes/Xfce-saltlake/gtk-2.0/gtkrc
/usr/share/themes/Xfce-smooth/gtk-2.0/
/usr/share/themes/Xfce-smooth/gtk-2.0/gtkrc
/usr/share/themes/Xfce-stellar/gtk-2.0/
/usr/share/themes/Xfce-stellar/gtk-2.0/gtkrc
/usr/share/themes/Xfce-winter/gtk-2.0/
/usr/share/themes/Xfce-winter/gtk-2.0/gtkrc
/usr/share/themes/Xfce/gtk-2.0/
/usr/share/themes/Xfce/gtk-2.0/gtkrc