请问，怎样给这个网页左右两边的广告条加个关闭按纽！！
参照网站www.sz-16.com效果   左右两边加了个随上下滚动的广告条，但是不会加关闭扭纽！~   请指教！！   那段JS代码如下


var   delta=0.15
var   collection;
function   floaters()   {
this.items   =   [];
this.addItem   =   function(id,x,y,content)
{
document.write( ' <DIV   id= '+id+ '   style= "Z-INDEX:   10;   POSITION:   absolute;   width:80px;   height:60px;left: '+(typeof(x)== 'string '?eval(x):x)+ ';top: '+(typeof(y)== 'string '?eval(y):y)+ ' "> '+content+ ' </DIV> ');

var   newItem   =   {};
newItem.object   =   document.getElementById(id);
newItem.x   =   x;
newItem.y   =   y;

this.items[this.items.length]   =   newItem;
}
this.play   =   function()
{
collection   =   this.items
setInterval( 'play() ',10);
}
}
function   play()
{

for(var   i=0;i <collection.length;i++)
{
var   followObj   =   collection[i].object;
var   followObj_x   =   (typeof(collection[i].x)== 'string '?eval(collection[i].x):collection[i].x);
var   followObj_y   =   (typeof(collection[i].y)== 'string '?eval(collection[i].y):collection[i].y);

if(followObj.offsetLeft!=(document.body.scrollLeft+followObj_x))   {
var   dx=(document.body.scrollLeft+followObj_x-followObj.offsetLeft)*delta;
dx=(dx> 0?1:-1)*Math.ceil(Math.abs(dx));
followObj.style.left=followObj.offsetLeft+dx;
}

if(followObj.offsetTop!=(document.body.scrollTop+followObj_y))   {
var   dy=(document.body.scrollTop+followObj_y-followObj.offsetTop)*delta;
dy=(dy> 0?1:-1)*Math.ceil(Math.abs(dy));
followObj.style.top=followObj.offsetTop+dy;
}
followObj.style.display   =   ' ';
}
}  

var   theFloaters   =   new   floaters();
theFloaters.addItem( 'followDiv1 ', 'document.body.clientWidth-110 ',130, ' <a   href= "index.htm "> <img   src=pop/images/right.gif   border=0> </a> <br> <br> ');
theFloaters.addItem( 'followDiv2 ',12,130, ' <a   href= "index.htm "   > <img   src=pop/images/left.gif   border=0> </a> <br> <br> ');
theFloaters.play();


------解决方案--------------------
大概构思了一下，把js调用的结果广告显示到Div层中间，关闭就是Div层的display 属性了，你这样试试
display= " " 显示时
display= "none " 关闭时