Yes please! The main thing I'd like this for is comparison to check that a MessageEvent's source is equal to a given iframes WindowProxy.
contentWindow :: HTMLIFrameElement -> Eff (dom :: DOM | eff) WindowProxy
https://github.com/purescript-web/purescript-dom/blob/9e624324f0ec63328f0cc269f168fd6c1ee9b337/src/DOM/HTML/HTMLIFrameElement.purs#L48