The d-u went through with no issues. Upon reboot, and with widgets locked, the system tray widget and the several items I have parked there, including volume, netman, and the "en" flag, are all missing from the panel. Unlocking widgets and reinstalling the systray works as expected, and the systray items are all there again, so that part of the configuration is unchanged. But the systray is not "integrated" in the panel configuration, apparently.