Comment 156 for bug 1335492

This works for me:
The first script is set to autostart on login.
The second one is used for logout / reboot.

https://forum.xfce.org/viewtopic.php?pid=49764#p49764

The first script waits untill all the the panels are in the window stack, then sets the folder permissions of .config/xfce/desktop to 755. It also removes all but the latest rc file when a new rc is created in the folder. Requires inotify-tools to monitor when the rc files are created.

The second script opens a yad dialog and sets the folder permissions of .config/xfce/desktop to non-writable when logout / shutdown / restart is selected. Requires yad.