In system settings, the button of display power management don’t disable. Is clickable and can see the options “Put to sleep after” and “Switch off after” stay frosted.
welcome at the forum
and do you already try restart lightdm and so the X-Session:
sudo systemctl restart lightdm
when i execute the command, first time, the button stay disable, but on second click continue enable
uh that’s odd but could be that the access is handled by different mechanisms and xfce first need to set some override or similar.
And xfce has still work to do on powermanagement, we had a hard time to configure the default settings to be generic usable.
I tried it on my Xfce set up which is not a laptop but seems to be the same. If you click on the button display power management you will notice “Put to sleep after” and “Switch off after” stay frosted.
If you close the window and later come back to it the display power management button will be unchecked. It does this automatically. If you enable it and the “Put to sleep after” and “Switch off after” are not frosted it will stay checked or on.
Just my observation on my system. I also restarted lightdm just to see but i don’t think that had any bearing on it. One way is XFCE Power Manement controls the functions and the other way is x11 controls it.
I do rememebr that i have a lot of issues like that on powersettings with xfce4.
It is also that xfce4 is saving stuff with gsettings database as a storage, but also creates config files under .config for the same settings… i do not understand why they do so, as p.e. others do use one or the other way or both but then for different settings…
So it happens that you set something up and nothing changed, till you do restart the session…
And on display management there are also kernel internal mechanisms and Xorg stuff could interfere with something… let’s hope next xfce4 upgrade will bring a better settings manager with it (the preview i tested was much better on this stuff)