code: public static Layer getHitLayer (Layer root, Point p) {
      root.transform().inverseTransform(p, p);
      p.x += root.originX();
      p.y += root.originY();
      return root.hitTest(p);
    }
docs: Returns the layer hit by (screen) position {@code p} (or null) in the scene graph rooted at
  {@code root}, using {@link Layer#hitTest}. Note that {@code p} is mutated by this call.