I am using 11.04 with Unity. When I press SUPER-W, the previews of open windows align on the screen. If I click one of them, it attains focus.
I used to have this enabled as a Compiz plugin in ccsm (not sure which one), but back then middle clicking on a window preview would close that window. Very useful.
How can I have middle-clicking close the preview I middle clicked in the SUPER-W pane?