Ubuntu / Apple :: Remap Mouse Button 3?

wondering if any other ppc users have had the issue whereby, after the first unsuccessful power down (or sometimes the second or third) of a fresh ubuntu 9.10 install, mouse button 3, which is normally mapped to F12, becomes function (fn) + F12.? This is really annoying as you now have to use two hands to activate the little drop down menu. So i tried remapping mouse button three to that strange little key beside the left arrow on an ibook keyboard that looks like a picnic table and which, under os x, renames stuff.

I ran "gksu gedit /etc/sysctl.d/10-arch-specific.conf" and edited it accordingly: mouse button 3 from keycode 88 to 104. It works, but i still have to press function to activate it and fn + F12 still works simultaneously (though it is no longer defined in the conf file), and my new key doesnt offer the same functionality (eg, it doesnt give spell check options in firefox where fn + F12 does). Arg. Anybody know how to make it so that i can activate mouse button three without having to press function?