Laptop backlight not turning off...

I'm going through the process of getting Slackware set up on a Dell
Inspiron 2200 at the moment.

One thing I've found is that the backlight refuses to turn off; after a
certain amount of time the display will blank, but it seems that the
backlight never switches itself off (even with the lid closed).

I'm not entirely sure which part of Linux should be responsible for this
(ACPI, X Windows, or something else), or even if it's a Linux problem at
all (i.e. is it Linux's responsibility to disable the backlight when the
lid's closed or after a certain period of inactivity - or is that entirely
a hardware thing?)

The 'change brightness' key combination for the laptop (Fn and up/down
cursor) does work, but it doesn't allow me to turn the backlight off
completely (but does at least suggest that low-level software access to
the backlight hardware is working!)

Any pointers as to how to set it up how I want? (I'm still thinking about
suspend/hibernate options, but at the very least I'd like the backlight to
go off when the lid's closed!)

System is Slackware 11, kernel updated to (ACPI enabled), Xorg
6.9.0 and the video chipset's an Intel 915GM.



we've fallen off the silly boat into a sea of ridiculousness!