code: function moveList( collapsedList, expandedList ) {
      const
          rect = collapsedList.getBoundingClientRect(),
          left = rect.left;
      let top = rect.top;
      while ( top <= 0 ) top += ITEM_HEIGHT;
      Dom.css( expandedList, {
          left: `${left}px`,
          top: `${top}px`
      } );
  }
docs: Try to move `expandedList` to make the selected item be exactly above the same item in
  `collapsedItem`. If it is not possible, a scroll bar will appear.
  @param {DOMElement} collapsedList - DIV showing only one item bcause the rest is hidden.
  @param {DOMElement} expandedList - DIV showing the most items as it can.
  @returns {undefined}