if ((width != null) && (east != null)) width = Spring.sum(east, Spring.minus(x));
h = null; if ((width != null) && (east != null) && (x != null)) width = null;
    public void setX(Spring s)    {      x = s;      if ((width != null) && (east != null))        width = Spring.sum(east, Spring.minus(x));    }