/usr/share/gconf/defaults/20_xubuntu-default-settings is in xubuntu-default-settings 12.04.11.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | /desktop/gnome/interface/gtk_theme "Greybird"
/desktop/gnome/interface/icon_theme "elementary-xfce-dark"
/apps/blueman/transfer/browse_command "exo-open obex://[%d]"
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