code: function(oColumn) {
      var selectedColumns = [];
      var aKeys = this._oColumnSet.keys;
      for(var i=0,len=aKeys.length; i<len; i++) {
          if(aKeys[i].selected) {
              selectedColumns[selectedColumns.length] = aKeys[i];
          }
      }
      return selectedColumns;
  }
docs: Returns an array selected Column instances.
  
  @method getSelectedColumns
  @return {YAHOO.widget.Column[]} Array of Column instances.