code: function(oColumn) {
      if(!(oColumn instanceof YAHOO.widget.Column)) {
          oColumn = this.getColumn(oColumn);
      }
      // Only top-level Columns can get hidden
      if(oColumn && oColumn.hidden && (oColumn.getTreeIndex() !== null)) {
          var allrows = this.getTbodyEl().rows;
          var l = allrows.length;
          var allDescendants = this._oColumnSet.getDescendants(oColumn);
          
          // Show each nested Column
          for(var i=0; i<allDescendants.length; i++) {
              var thisColumn = allDescendants[i];
              thisColumn.hidden = false;
              
              // Unstyle the head cell
              Dom.removeClass(thisColumn.getThEl(), DT.CLASS_HIDDEN);
  
              // Does this Column have body cells?
              var thisKeyIndex = thisColumn.getKeyIndex();
              if(thisKeyIndex !== null) {
                  // Restore minWidth
                  this._restoreMinWidth(oColumn);
                  
              
                  // Unstyle the body cells
                  for(var j=0;j<l;j++) {
                      Dom.removeClass(allrows[j].cells[thisKeyIndex],DT.CLASS_HIDDEN);
                  }
              }
  
              this.fireEvent("columnShowEvent",{column:thisColumn});
          }
          this._clearTrTemplateEl();
      }
      else {
      }
  }
docs: Shows given Column. NOTE: You cannot hide/show nested Columns. You can only
  hide/show non-nested Columns, and top-level parent Columns (which will
  hide/show all children Columns).
  
  @method showColumn
  @param oColumn {YAHOO.widget.Column} Column instance.