Gnome shell extension for closing apps in overview with a middle click
All credit goes to Paolo Tranquilli (http://cs.unibo.it/~tranquil/en/hacking.html), I've merely copied its code here to provide Gnome Shell 3.10+ compatibility
This extension is installable from https://extensions.gnome.org/extension/352/middle-click-to-close-in-overview/.
Otherwise you may
* download a [zip](https://github.com/p91paul/middleclickclose/archive/master.zip) of this extension
* extract it
* copy folder middleclickclose@paolo.tranquilli.gmail.com in $HOME/.local/share/gnome-shell/extensions