网页右下角弹出的消息窗口层，能支持firefox，可以动画伸缩，怎么做的

var oPopup = window.createPopup();
var popTop=50;
function popmsg(msgstr)
{
var winstr="<table style=\"border: 1 solid #FFA6CA\" width=\"241\" height=\"172\" border=\"0\" cellpadding=\"0\" cellspacing=\"0\" background=\"./images/001.jpg\" >";
winstr+="<tr><td height=\"30\"> </td></tr><tr><td align=\"center\"><table width=\"90%\" height=\"110\" border=\"0\" cellpadding=\"0\" cellspacing=\"0\">";
winstr+="<tr><td valign=\"top\" style=\"font-size:12; color: #FF0000; face: Tahoma\">"+msgstr+"</td></tr></table></td></tr></table>";
oPopup.document.body.innerHTML = winstr;
popshow();
}
function popshow()
{
window.status=popTop;
if(popTop>1720)
{
clearTimeout(mytime);
oPopup.hide();
return;
}
else if(popTop>1520&&popTop<1720)
{
oPopup.show(screen.width-250,screen.height,241,1720-popTop);
}
else if(popTop>1500&&popTop<1520)
{
oPopup.show(screen.width-250,screen.height+(popTop-1720),241,172);
}
else if(popTop<180)
{
oPopup.show(screen.width-250,screen.height,241,popTop);
}
else if(popTop<220)
{
oPopup.show(screen.width-250,screen.height-popTop,241,172);
}
popTop+=10;
var mytime=setTimeout("popshow();",20);
}
popmsg("文本信息");
放在title中