It seemed that my problem was related to Bug #1200829. For those of you who experience the same problem I had, the fix is given in the PPA:
ppa:mc3man/test-scroll -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1171342 Title: mouse scroll wheel not working in gedit & System Monitor To manage notifications about this bug go to: https://bugs.launchpad.net/gtk/+bug/1171342/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp
