Mouse wheel click widgets - ??

When i had my mighty mouse, the mouse wheel when clicked opened my widgets.

Now ive switched to a wired optical mouse, Non apple brand it doesnt work.
Ive searched all the settings and cant find an option to tick or select to allow the mouse wheel click to access widgets.

Im sure im missing something here as i know you can do it and im tearing my chest hair out trying to figure this out.

Ive googled around loads and i must not be using the right search terms as its just not showing up what so ever.

If anyone can help id be very gratefull.

thanks - n00b mike

 

Well would you believe it! i found it after one last attempt!
for anyone else with the same problem here it is


Settings > Expose & Spaces > Bottom section 'Dashboard' > 2nd Drop down menu


doh! haha