function handleHeaderMouseEnter(e, args) {
      var column = args.column,
          $node = $(e.target).closest(".slick-header-column");
      if (!column.toolTip) {
        $node.attr("title", ($node.innerWidth() < $node[0].scrollWidth) ? column.name : "");
      }
    }
Handle mouse entering header cell to add/remove tooltip.
@param {jQuery.Event} e     - The event
@param {object} args.column - The column definition