Fixed in a slightly hacky way. See Rev 22 PXLayerController.m - made PXCanvasController the next responder for PXLayerController's stuff, indirectly. Had to override mouseMoved to account for the drawer's size and offset... had to use some magic numbers for the drawer's border size. They're not totally not in any documentation or headers. Annoying as hell. Anyway, it works, but should probably be tested more thoroughly than I've done.