FYI, the previous panel config was $somexdgdir/xfce4/panel/panel.xml and a rc file in $somexdgdir/xfce4/panel/ for each plugin. In 4.8, the config has been moved to xfconf, so it will be $somexdgdir/xfce4/xfconf/xfce-perchannel-xml/xfce4-panel.xml. There are still plugins not migrated to xfconf, so they still drop rc files in $somexdgdir/xfce4/panel/.
($somexdgdir being either $XDG_CONFIG_HOME or a dir from $XDG_CONFIG_DIRS)
FYI, the previous panel config was $somexdgdir/ xfce4/panel/ panel.xml and a rc file in $somexdgdir/ xfce4/panel/ for each plugin. In 4.8, the config has been moved to xfconf, so it will be $somexdgdir/ xfce4/xfconf/ xfce-perchannel -xml/xfce4- panel.xml. There are still plugins not migrated to xfconf, so they still drop rc files in $somexdgdir/ xfce4/panel/ .
($somexdgdir being either $XDG_CONFIG_HOME or a dir from $XDG_CONFIG_DIRS)