code: function() {
      var allOptions = this.dropdown.options;
      
      // Look for multiple selections
      if(this.multiple) {
          var values = [],
              i=0, j=allOptions.length;
          for(; i<j; i++) {
              if(allOptions[i].selected) {
                  values.push(allOptions[i].value);
              }
          }
          return values;
      }
      // Only need to look for single selection
      else {
          return allOptions[allOptions.selectedIndex].value;
      }
  }
docs: Retrieves input value from DropdownCellEditor.
  
  @method getInputValue