code: public static void apply(Widget widget, Double offset) {
          apply(widget, null, null, offset);
      }
docs: A pushpinned element has 3 states. One above and below the scrolling threshold,
  and the pinned state where the element becomes fixed.
  
  @param widget - Target widget to apply the pushpin feature
  @param offset - The offset from the top the element will be fixed at. (Default: 0)