Can't find xf86search key binding (want to turn it off)

My mouse (Logitech MX Revolution) has a “search” button which is mapped as key 229 = xf86search.

However, I like to use this button to close open windows. In Fedora the key was not mapped by default so I was able to put the mapping in xmodmap and then set up the close window binding in Compiz. In OpenSUSE, the button by default brought up the Beagle desktop search. I uninstalled Beagle, and now it brings up the Nautilus “Search for Files” dialog.

I’ve looked high and low but I can’t seem to figure out how to unbind this button so I can use it for what I want.

Any help/insight is much appreciated by this new Linux user!

Actually, let me phrase this differently:

How would I go about changing the keyboard shortcut to the Nautilus search?