var handle;
function start()
{
    var obj = document.getElementById("tip");
    if (parseInt(obj.style.height)==0)
    {    obj.style.display="block";
        handle = setInterval("changeH('up')",2);
    }else
    {
        handle = setInterval("changeH('down')",2)    
    }    
}
function changeH(str)
{
    var obj = document.getElementById("tip");
    if(str=="up")
    {
        if (parseInt(obj.style.height)>150)
            clearInterval(handle);
        else
            obj.style.height=(parseInt(obj.style.height)+8).toString()+"px";
    }
    if(str=="down")
    {
        if (parseInt(obj.style.height)<8)
        {    clearInterval(handle);
            obj.style.display="none";
        }
        else        
            obj.style.height=(parseInt(obj.style.height)-8).toString()+"px";    
    }
}