jQuery / 百度空间各种特效，高手修改JS 兼容 FF

=====这是里面的 拖动代码，但是不兼容 FF, 谁能把里面 改一下，让他兼容FF
var Dragdrop=new Class();
Dragdrop.prototype=
{
  initialize:function(width,height,shadowWidth,showShadow,contentType)
  {
    this.dragData=null;
    this.dragDataIn=null;
    this.backData=null;
    this.width=width;
    this.height=height;
    this.shadowWidth=shadowWidth;
    this.showShadow=showShadow;
    this.contentType=contentType;
    this.IsDraging=false;
    this.oObj=G('dialogBox');
    Event.observe(G('dialogBoxTitle'),"mousedown",this.moveStart.bindAsEventListener(this),false)
  }
  ,moveStart:function(event)
  {
    this.IsDraging=true;
    if(this.contentType==1)
    {
      G("iframeBG").style.display="";
      G("iframeBG").style.width=this.width;
      G("iframeBG").style.height=this.height
    };
    Event.observe(document,"mousemove",this.mousemove.bindAsEventListener(this),false);
    Event.observe(document,"mouseup",this.mouseup.bindAsEventListener(this),false);
    Event.observe(document,"selectstart",this.returnFalse,false);
    this.dragData=
    {
      x:Event.pointerX(event),y:Event.pointerY(event)
    };
    this.backData=
    {
      x:parseInt(this.oObj.style.left),y:parseInt(this.oObj.style.top)
    }
  }
  ,mousemove:function(event)
  {
    if(!this.IsDraging)return;
    var iLeft=Event.pointerX(event)-this.dragData["x"]+parseInt(this.oObj.style.left);
    var iTop=Event.pointerY(event)-this.dragData["y"]+parseInt(this.oObj.style.top);
    if(this.dragData["y"]<parseInt(this.oObj.style.top))iTop=iTop-12;
    else if(this.dragData["y"]>parseInt(this.oObj.style.top)+25)iTop=iTop+12;
    this.oObj.style.left=iLeft;
    this.oObj.style.top=iTop;
    if(this.showShadow)
    {
      G('dialogBoxShadow').style.left=iLeft+this.shadowWidth;
      G('dialogBoxShadow').style.top=iTop+this.shadowWidth
    };
    this.dragData=
    {
      x:Event.pointerX(event),y:Event.pointerY(event)
    };
    document.body.style.cursor="move"
  }
  ,mouseup:function(event)
  {
    if(!this.IsDraging)return;
    if(this.contentType==1)G("iframeBG").style.display="none";
    document.onmousemove=null;
    document.onmouseup=null;
    var mousX=Event.pointerX(event)-(document.documentElement.scrollLeft||document.body.scrollLeft);
    var mousY=Event.pointerY(event)-(document.documentElement.scrollTop||document.body.scrollTop);
    if(mousX<1||mousY<1||mousX>document.body.clientWidth||mousY>document.body.clientHeight)
    {
      this.oObj.style.left=this.backData["x"];
      this.oObj.style.top=this.backData["y"];
      if(this.showShadow)
      {
        G('dialogBoxShadow').style.left=this.backData.x+this.shadowWidth;
        G('dialogBoxShadow').style.top=this.backData.y+this.shadowWidth
      }
    };
    this.IsDraging=false;
    document.body.style.cursor="";
    Event.stopObserving(document,"selectstart",this.returnFalse,false)
  }
  ,returnFalse:function()
  {
    return false
  }
};