         // disposers 用来收集资源销毁函数，并在析构时自动调用！
                {
                    this._disposers = [];
                    this._disposers.push(XE.MVVM.bind(this, 'twoPostionsEditing', viewshed, 'twoPostionsEditing'));
                    this._disposers.push(XE.MVVM.bind(this, 'positionEditing', viewshed, 'positionEditing'));
                    this._disposers.push(XE.MVVM.bind(this, 'rotationEditing', viewshed, 'rotationEditing'));
                    this._disp