Martin,

Thanks for your analysis. At least that makes sense, even if a clean solution is
not immediately obvious.

Creating and artificial minimum seems rather arbitrary and would a minimum of,
say, 20% of the maximum value even be sane and suitable on all hardware? I don't
have any suitable hardware for real testing, so would have to rely on reports
from you and others.

Getting all DEs to cooperate in unblanking seems a tall order.

I agree the script seems suboptimal in many ways.

Maybe we could support configuring a minimum in /etc/default/brightness?

At least you have a workaround that will avoid the issue for you again. If you
get any other ideas about clean fixes, do say.

Mark