Comment 5 for bug 1250401

The problem here is that the gsd-backlight-helper code used by the brightness applet prefers to always use 'acpi_video0' or whatever backlight device has type 'firmware'. This means that it will update /sys/class/backlight/acpi_video0/brightness, which does not work. Our test code will update the intel_backlight device, which does work but is meaningless because the OS doesn't use that same interface. Bottom line is that this is probably a firmware issue (but could possibly be a kernel issue). That's my $0.02