I just found, that gnome-settings-daemon was running on my system and that killing it got me rid of that issue. However I still think xfce4-power-manager-settings should have told me that there was an issue with the configuration. Also, when starting gnome-settings-daemon on the command line and waiting 10 seconds, the following pops up as soon as the display backlight gets dimmed:
(gnome-settings-daemon:16612): power-plugin-WARNING **: IsInhibited failed: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files
I also found the backlight dimming options in gconf-editor in /apps/gnome-power-manager/backlight and deactivated all entries, which didn't help.
I just found, that gnome-settings- daemon was running on my system and that killing it got me rid of that issue. However I still think xfce4-power- manager- settings should have told me that there was an issue with the configuration. Also, when starting gnome-settings- daemon on the command line and waiting 10 seconds, the following pops up as soon as the display backlight gets dimmed:
(gnome- settings- daemon: 16612): power-plugin- WARNING **: IsInhibited failed: GDBus.Error: org.freedesktop .DBus.Error. ServiceUnknown: The name org.gnome. SessionManager was not provided by any .service files
I also found the backlight dimming options in gconf-editor in /apps/gnome- power-manager/ backlight and deactivated all entries, which didn't help.