函数如下：
//减低透明度
function high(which1)
{
theobject=which1
theobject.filters.alpha.opacity=0
highlighting=setInterval("highlightit(theobject)",60)
}
//提高透明度
function low(which1){
clearInterval(highlighting)
which1.filters.alpha.opacity=60}
//透明度递减
function highlightit(cur2){
if (cur2.filters.alpha.opacity<100)
cur2.filters.alpha.opacity+=20
else if(window.highting)
clearInterval(highlighting)
}
调用的例子：
<img src="a.gif" onmouseout=low(this) onmouseover=high(this)>