code: function(e, el, prop) {
              var command = this._getCommand(e),
                  inc = (e.shiftKey) ? 10 : 1;
              switch (command) {
                  case 6: // return, update the value
                      this._useFieldValue.apply(this, arguments);
                      break;
                              
                  case 3: // up arrow, increment
                      this.set(prop, Math.min(this.get(prop)+inc, 255));
                      this._updateFormFields();
                      //Event.stopEvent(e);
                      break;
                  case 4: // down arrow, decrement
                      this.set(prop, Math.max(this.get(prop)-inc, 0));
                      this._updateFormFields();
                      //Event.stopEvent(e);
                      break;
  
                  default:
              }
  
          }
docs: Handle keypress on one of the rgb or hsv fields.
  @method _rgbFieldKeypress
  @param e {Event} the keypress event
  @param el {HTMLElement} the field
  @param prop {string} the key to the linked property
  @protected