code: function addRow(gui, dom, liBefore) {
      var li = document.createElement('li');
      if (dom) li.appendChild(dom);
      if (liBefore) {
        gui.__ul.insertBefore(li, params.before);
      } else {
        gui.__ul.appendChild(li);
      }
      gui.onResize();
      return li;
    }
docs: Add a row to the end of the GUI or before another row.
  
  @param gui
  @param [dom] If specified, inserts the dom content in the new row
  @param [liBefore] If specified, places the new row before another row