Linux Mint 14 screen brightness changes twice
 

On my Aspire One 722, whenever I try to change the screen brightness via the keyboard, the brightness changes in 2 steps. I believe that what's happening is the hardware is changing the brightness, then the software is changing it again.

In the past, I've dealt with it by turning off software brightness control via the following setting change
However, as of Mint 14 this does not appear to work (this option doesn't exist, and disabling it doesn't appear to have any effect).

How do I disable software control of screen brightness?