code: function (val) {
              var rv = false;
  
              if (JS.isNumber(val)) {
                  rv = val > 0 && val <= this.get("numItems");
              } else if (JS.isArray(val)) {
                  if (JS.isNumber(val[0]) && JS.isNumber(val[1])) {
                      rv = val[0] * val[1] > 0 && val.length == 2;
                  }
              }
  
              return rv;
          }
docs: Validate the numVisible value.
  
  @method _validateNumVisible
  @param val {Number} The numVisible value
  @return {Boolean} The status of the validation
  @protected