Another gnome-control-center hard code freeze break

[Cosimo Cecchi <cosimoc gnome org>]

Hi,

another hard code freeze break request for gnome-control-center.
- https://bugzilla.gnome.org/show_bug.cgi?id=646240
Some hboxes in the Universal Access panel (Pointing and Clicking tab)
were incorrectly marked as insensitive, which would cause them not to
react to the activation of the relative switch. Patch is straightforward
and has been tested to work fine by me and Benjamin (which discovered
this while working on another GTK+ sensitivity bug).

Ok to push?

Thanks,
Cosimo