Comment 1 for bug 327926

I think I might have a better solution than our current patching of libxfce4util: drop a 70xubuntu_session (from xubuntu-default-settings) in /etc/X11/Xsession.d that exports XDG_CONFIG_DIRS and XDG_DATA_DIRS. This will be sourced before 75dbus_dbus-launch, which therefore should be spawned with the correct environment. And for mythbuntu, you can add a 71mythbuntu_session in mythbuntu-default-settings if you want to override xubuntu's settings again.

What do you think? I'll try to play with that in a vm to see if it works as expected.