code: function() {
      // Remove all cells from tracker
      var tracker = this._aSelections || [];
      for(var j=tracker.length-1; j>-1; j--) {
         if(lang.isObject(tracker[j])){
              tracker.splice(j,1);
          }
      }
  
      // Update tracker
      this._aSelections = tracker;
  
      // Update UI
      this._unselectAllTdEls();
  
      //TODO: send data to unselectAllCellsEvent handler
      this.fireEvent("unselectAllCellsEvent");
  }
docs: Clears out all cell selections.
  
  @method unselectAllCells