super/windows won't work as bucky key for Keyboard Shortcuts

[Msquared]

FC4t1, trying to make super-1 through super-4 switch to desktops 1 through
4.  This used to work on my FC1 box, but now super (aka "the windows key")
behaves like a normal keystroke (eg "F1", "A", "Enter"), rather than like
a bucky key (eg "Shift", "Ctrl", "Alt").

Is there something I can do to fix this?

Regards, Msquared...