给FF添加了IE专有的属性和方法：

<script language="JavaScript" type="Text/JavaScript">
<!--
if(window.Event){// 修正Event的DOM
    Event.prototype.__defineSetter__("returnValue",function(b){//
        if(!b)this.preventDefault();
        return b;
        });
    Event.prototype.__defineSetter__("cancelBubble",function(b){// 设置或者检索当前事件句柄的层次冒泡
        if(b)this.stopPropagation();
        return b;
        });
    Event.prototype.__defineGetter__("srcElement",function(){
        var node=this.target;
        while(node.nodeType!=1)node=node.parentNode;
        return node;
        });
    Event.prototype.__defineGetter__("fromElement",function(){// 返回鼠标移出的源节点
        var node;
        if(this.type=="mouseover")
            node=this.relatedTarget;
        else if(this.type=="mouseout")
            node=this.target;
        if(!node)return;
        while(node.nodeType!=1)node=node.parentNode;
        return node;
        });
    Event.prototype.__defineGetter__("toElement",function(){// 返回鼠标移入的源节点
        var node;
        if(this.type=="mouseout")
            node=this.relatedTarget;
        else if(this.type=="mouseover")
            node=this.target;
        if(!node)return;
        while(node.nodeType!=1)node=node.parentNode;
        return node;
        });
    Event.prototype.__defineGetter__("offsetX",function(){
        return this.layerX;
        });
    Event.prototype.__defineGetter__("offsetY",function(){
        return this.layerY;
        });
    }
if(window.Document){// 修正Document的DOM
    }
if(window.Node){// 修正Node的DOM
    Node.prototype.replaceNode=function(Node){// 替换指定节点
        this.parentNode.replaceChild(Node,this);
        }