feature/ui addition request for gnome-screensaver

[William Jon McCann <mccann jhu edu>]

Hi,

I'd like to add the following feature and bit of UI:
http://bugzilla.gnome.org/show_bug.cgi?id=347721

This feature is off by default.  But it is really essential for all 
keyboardless touch screen systems.

Ok to land this?

Thanks,
Jon