1.在使用Angular Material对话框时，对话框显示以后，点击浏览器的返回按钮对话框不会消失的问题，解决方法就是监听$stateChangeStart事件，如果对话框已经显示则取消对话框并阻止下一步事件

 .run(['$rootScope','$state','$stateParams','SessionStorage','ENV','$mdDialog','$document',function ($rootScope,$state,$stateParams,SessionStorage,ENV,$mdDialog,$document) {
            $rootScope.$state = $state;
            $rootScope.$stateParams = $stateParams;
            $rootScope.$on("$stateChangeSuccess",function (event,toState,toParams,fromState,fromParams) {
                // to be used for back button //won't work when page is reloaded.
                $rootScope.prevIoUsState_name = fromState.name;
                $rootScope.prevIoUsState_params = fromParams;
            });
            //back button function called from back button's ng-click="back()"
            $rootScope.back = function () {
                $state.go($rootScope.prevIoUsState_name,$rootScope.prevIoUsState_params);
            };
            $rootScope.$on('$stateChangeStart',function(event,fromParams,options){
                    if(angular.element($document[0].body).hasClass('md-dialog-is-showing')) {
                        $mdDialog.cancel();
                        event.preventDefault();
                    }
                });
        }
    ]);