Comment 13 for bug 41994

I'm not sure if it'll have any ill effects, but my problem went away by commenting out all lines in the
/etc/acpi/events/videobtn file and then rstarting acpid. I assume this causes the acpid to ignore the
event that is triggering the backlight to come back on when the lid is still closed.

The backlight now stays off unless the lid is opened or an actual button is pressed.