Someone was at one point, but your point is taken; we're finding a type issue with it that I vaguely recall being an attempt to work around some ancient ghc weirdness that no longer applies, related to it insisting the declaration of onlyFor and the declaration of the LayoutModifier instance looking the same (which overconstrains it so it won't work when used in a chain with something else; removing the overconstraint works with current ghc).  Forget this patch and I'll resubmit when we have it working again.  (I can't test it locally beyond compiling it, yet; my environment is a complete mess.)