Comment 6 for bug 1041105

Upstream changed it in that commit:
http://git.gnome.org/browse/gsettings-desktop-schemas/commit/?id=19fe99f2f9ed8ebc77fd28465906db33c4782604

"wm-schemas: Change default mouse-button-modifier

Some applications (mostly graphics) use alt-click and alt-drag for actions, which conflicts with the current default; change the default modifier to <Super>, which is already prominently used as overview key, so using it for other window manager functionalities is pretty reasonable.

https://bugzilla.gnome.org/show_bug.cgi?id=607797 "