If a user wants to run two simultaneous sessions from the same Home directory
the XFCE config space can be set individually using different values of XDG_CONFIG_HOME and XDG_CACHE_HOME for the two sessions. This works for all components I have checked but not for xfce-panel. So changes to the panel in session 1 overwrite changes in session 2. This is very inconvenient for this type of scenario. I encounter this when running a normal desktop session on my work machine in parallel to a second session running under X2GO (to be used when I work from home or on the road) on the same home directory.
I did not reproduce exactly this problem, but a similar behavior by alternating sessions with and without environment variables set. Changes made in one are carried over into the other, when they shouldn't be.
If I open a blank session with variables set, the default configuration is loaded, but when I return to my normal session, not everything is restored. The launchers, at least, are broken.
So I think we can leave this issue open, there are probably bugs to be fixed or improvements to be made (it would require more investigation to distinguish between the two).
No actually it works, I must not have set the variables for Xfconf correctly. You should think about running it by hand in a terminal to test. Otherwise, as part of the original problem, you would have to define the variables somewhere upstream, but it might not be so obvious for a dbus service in session sharing...
Anyway there is no problem with the panel here, so I'm closing.