mootools setOptions 發生too much recursion問題

 兩個很簡單的類

Container = new Class({
    Implements: [Events, Options],
    layout: null,
    initialize: function(options){
        this.setOptions(options);
    },
    setLayout: function(l){
        this.layout = l;
        this.layout.setContainer(this);
    }
});

Layout = new Class({
    Implements: [Events, Options],
    options: {
        item: null
    },
    container: null,
    initialize: function(o){
        this.setOptions(o);
    },
    setContainer: function(c){
        this.container = c;
    }
});

window.addEvent('domready', function(){
    var innerContainer = new Container();
    
    innerContainer.setLayout(new Layout());
    
    var container = new Container();
    var layout = new Layout({
        item: innerContainer
    });
});

執行的時候出現了：too much recursion
跟蹤代碼發現setOption方法會調用$unlink()方法，其中有遞歸代碼：
for (var p in object) unlinked[p] = $unlink(object[p]);進行深度copy，把參數複制到options中。

而這段代碼中Container和Layout是雙向關聯的。
container.setLayout()時又會把layout賦給container，而
this.layout.setContainer(this)又會把container賦給layout，是以就會出現遞歸調用而出錯了