问AngularJS控制器中的'this'和$ scope？

controller: function($scope, $element) {

  var panes = $scope.panes = [];

  $scope.select = function(pane) {

    angular.forEach(panes, function(pane) {

      pane.selected = false;

    });

    pane.selected = true;

  }

  this.addPane = function(pane) {

    if (panes.length == 0) $scope.select(pane);

    panes.push(pane);

  }

}