One of those things that's incredibly useful, but not built in... I figure others may be googling for this one day.
I found the source for https://pursuit.purescript.org/packages/purescript-pux/11.0.0/docs/Pux.DOM.History very useful!
Here is a commit adding it to my app: https://github.com/dlants/doodleometry/commit/43d38a3d6d4c8c755cdbe63b690837bdd2085a93
module SampleWindow (sampleWindowSize) where
import Control.Alternative (pure)