ui-select/src/uisOpenCloseDirective.js

uis.directive('uisOpenClose', ['$parse', '$timeout', function ($parse, $timeout) {
  return {
    restrict: 'A',
    require: 'uiSelect',
    link: function (scope, element, attrs, $select) {
      $select.onOpenCloseCallback = $parse(attrs.uisOpenClose);

      scope.$watch('$select.open', function (isOpen, previousState) {
        if (isOpen !== previousState) {
          $timeout(function () {
            $select.onOpenCloseCallback(scope, {
              isOpen: isOpen
            });
          });
        }
      });
    }
  };
}]);