To enable window rolling in Ubuntu 12.04 when you are using Unity edit the following entry in Configuration Editor:
/ ▸ apps ▸ gwd ▸ mouse_wheel_action
and change the value to “shade” without quotes. Now mouse wheel scroll-up on title bar rolls your windows and scroll-down unrolls them.
Update: To set the mouse_wheel_action key (or reset it) without installing Configuration Editor (which is not installed by default) use the following commands as current user:
$ gconftool-2 -s /apps/gwd/mouse_wheel_action -t string “shade”
$ gconftool-2 -s /apps/gwd/mouse_wheel_action -t string “none”