code: function validatorNum( msg ) {
  		return function() {
  			var value = this.getValue(),
  				pass = !!( CKEDITOR.dialog.validate.integer()( value ) && value > 0 );
  
  			if ( !pass ) {
  				alert( msg );
  				this.select();
  			}
  
  			return pass;
  		};
  	}
docs: Whole-positive-integer validator.