Correct way to extend Bootstrap Modal - lock, unlock

I'm trying to extend bootstrap 3 modal window with ability to disable closing it.

I've built this code:

(function ($, window, document, undefined) {
    var oldHide = $.fn.modal.Constructor.prototype.hide;

    $.fn.modal.Constructor.prototype.hide = function (_relatedTarget) {
        if (this.isLocked) return;
        return oldHide.call(this, _relatedTarget);
    };

    $.fn.modal.Constructor.prototype.lock = function (_relatedTarget) {
        this.isLocked = true;
        e = $.Event('lock.bs.modal', {
            relatedTarget: _relatedTarget
        });
        this.$element.trigger(e);
    };

    $.fn.modal.Constructor.prototype.unlock = function (_relatedTarget) {
        this.isLocked = false;
        e = $.Event('unlock.bs.modal', {
            relatedTarget: _relatedTarget
        });
        this.$element.trigger(e);
    };

})(jQuery, window, document);

Working demo

After clicking "lock," you won't be able to close modal until you click "unlock."

It this way of extending bootstrap modal correct? What are potential dangers of doing this?

And how can I make this better?

EDIT:

This is my final version based on suggestions.

Looks fine to me, except that you failed declare the e variable in the lock/unlock functions. So it's an automatic global, which isn't good.

With a little bit of cleanup:

(function ($) {
  var _original = $.fn.modal.Constructor.prototype.hide;

  function trigger(target, name, relatedTarget) {
    target.trigger($.Event(name, { relatedTarget: relatedTarget }));
  }

  $.extend($.fn.modal.Constructor.prototype, {
    hide: function (_relatedTarget) {
      if (this.isLocked) return;
      return _original.call(this, _relatedTarget);
    },

    lock: function (_relatedTarget) {
      this.isLocked = true;
      trigger(this.$element, 'lock.bs.modal', _relatedTarget);
    },

    unlock: function (_relatedTarget) {
      this.isLocked = false;
      trigger(this.$element, 'unlock.bs.modal', _relatedTarget);
    }
  });
})(jQuery);

StackExchange Code Review Q#51925, answer score: 8