code: public static Layer layerUnderPoint (Layer root, float x, float y) {
      Point p = new Point(x, y);
      root.transform().inverseTransform(p, p);
      p.x += root.originX();
      p.y += root.originY();
      return layerUnderPoint(root, p);
    }
docs: Gets the layer underneath the given screen coordinates, ignoring hit testers. This is
  useful for inspecting the scene graph for debugging purposes, and is not intended for use
  is shipped code. The layer returned is the one that has a size and is the deepest within
  the graph and contains the coordinate.