>Following the initialisation I now see that the Qt5 systray set-up fails because there's nothing listening on the DBus
I think you've only half analysed this. If nothing is really listening on DBus it will fall back to legacy X which will work on XFCE. You'll get into this situation if you have a StatusNotifierItemWatcher (typically a kded module from p-w) but no StatusNotifierItem host (sys tray support) David
