mouse wheel workspace switcher?

[Beartooth]

	Another subscriber on a LUG I follow asks : 

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	On my laptop running Ubuntu 8.04 I stumbled across
a setting that lets me switch workspaces using the
mouse wheel when the pointer is on the background.

I like this feature very much and would like it on
my desktop Fedora 9 also.  Now I can't find where
I made the setting on Ubuntu nor on Fedora.

Anyone recognize the feature and know where the
setting is found?
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	It so happens that I have had that, or something it sounds like, 
happen to me a time or two -- and been infuriated. So I hope very much 
that someone here can name it, and maybe tell where it is or how to 
install/uninstall it (if it's one part of some package); then he can 
delight in it, and I can delight in being safe from it. TIA!

-- 
Beartooth Staffwright, PhD, Neo-Redneck Linux Convert
Fedora 8 & 9; Alpine 1.10, Pan 0.132; Privoxy 3.0.6;
nine (count 'em -- nine) different browsers
Remember I know precious little of what I am talking about.