ashinkarov/i3-extras — pull request #8 by AladW (2014-06-12 02:46:37+00:00)
Title: Create i3-mouse-close.patch

As the name says - allows you to close windows witht he middle mouse button. :)

Source: https://faq.i3wm.org/question/550/manipulating-windows-with-the-mouse/?answer=1252#post-id-1252