An additional joke, likely unintentional (but who knows), is that the original Monads of Leibniz, were viewed as completely independent, 'windowless', objects that only seemed to interact with one another via God's elaborate choreography, which he termed the 'pre-established harmony' of the universe.
https://en.wikipedia.org/wiki/Pre-established_harmony
XMonad of course, has windows.
And now for an actually funny joke about Leibniz:
http://existentialcomics.com/comic/108