This morning the display blanked and flittered shortly after a boot. This appears to be an ongoing problem with xfce4-power-manager version 4.18.3-2.
I could not regain control and had to reboot. The immediate problem did not recur on that reboot, and I investigated the settings to see if something had changed. There I discovered that the "Handle display brightness keys" toggle was off. I turned it on, and the brightness keys then worked again. So that would seem to have cleared this bug. However it apears that something changed those settings, perhaps during the upgrade. There is clearly a bug here somewhere, but perhaps not with the plugins. So with some hesitation, I will provisionally close this bug. ael
