issue extending angular-ui-bootstrap tooltip

Question

I'm attempting to build an extended version of the Angular UI Bootstrap tooltip although it's really more of a translation of the $modal provider into a tooltip provider

my intent is to create a tooltip that will have its own controller - in much the same way as can be done with the $modal provider

I tried creating a tooltipExtended directive like so:

    .directive('tooltipExtended', [ 'tooltipStack', '$timeout', function (tooltipStack, $timeout) {
        return {
                    restrict: 'EA',
                    scope: {
                        index: '@',
                        animate: '=',
                        placement: '@'
                    },
                    replace: true,
                    transclude: true,
                    templateUrl: function (tElement, tAttrs) {
                        return tAttrs.templateUrl || 'template/tooltip/extended.html';
                    },
                    link: function (scope, element, attrs) {
                        //....etc....
                    }
                };
            }
        ]);

    .directive('tooltipTransclude', function () {
        return {
            link: function ($scope, $element, $attrs, controller, $transclude) {
                $transclude($scope.$parent, function (clone) {
                    $element.empty();
                    $element.append(clone);
                });
            }
        };
    });

    angular.module("template/tooltip/extended.html", []).run(["$templateCache", function ($templateCache) {
        $templateCache.put("template/tooltip/extended.html",
          "<div tabindex=\"-1\" role=\"tooltip\" class=\"tooltip {{placement}}\" ng-class=\"{in: animate}\" ng-style=\"{'z-index': 1050 + index*10, display: 'block'}\" ng-click=\"close($event)\">\n" +
          "    <div class=\"tooltip\"><div class=\"tooltip-content\" tooltip-transclude></div></div>\n" +
          "</div>");
    }]);

and then using the tooltipStack (again, basically mirroring the $modalStack, just without a backdrop) - I do the following in the tooltipStack.open function:

        // ...
        var body = $document.find('body').eq(0);

        var angularDomEl = angular.element('<div tooltip-extended></div>');
        var index = openedTooltips.length() - 1;
        angularDomEl.attr({
            'template-url': tooltip.tooltipTemplateUrl,
            'tooltip-class': tooltip.tooltipClass,
            'index': index,
            'placement': tooltip.placement,
            'animate': 'animate'
        }).html(tooltip.content);

        var tooltipDomEl = $compile(angularDomEl)(tooltip.scope);
        // ...

when I do this, it doesn't seem as though the controller is binding to the tooltip

if I change this to use the existing Angular UI Bootstrap tooltip directive (which calls into the $tooltip provider) like so:

var angularDomEl = angular.element('<div tooltip></div>');

everything suddenly works fine, but looking through the compile function for the $tooltip provider, I don't understand what makes this difference - the only code that executes is basically the construction logic for the $tooltip provider's link function that's returned by the $get

in case you're curious - to get the tooltip position, this extension relies on sending the angular.element($event.target) from whatever event is used to trigger the tooltip

any suggestions?