I posted a frontlight control KUAL extension over here:
https://www.mobileread.com/forums/sho...13#post3323913
It lets you turn the paperwhite frontlight completely off (plus other settings). Resuming from screensaver restores the brightness value set with the control panel brightness slider.
There have been reports that you can turn the backlight off by sliding to minimum brightness and then tapping "minus" (or "dim" or whatever that icon means). However, this never worked on my PW1 or PW2 or PW3. This extension DOES work (just tested on my PW2 and PW3).
And I will add the extension download here too...
But for details, read the linked post.