var timer = 0;
var delay = 1; //msec
var scrollOffset = 39; //pixel
var docBody;

function init(){
	docBody = document[getDocElName()];
}

function goDown(targetYPos) {
    var y = docBody.scrollTop;
    if (y<targetYPos){
        window.scrollBy(0, scrollOffset);
        timer = setTimeout('goDown('+targetYPos+')', delay);
    }
    else clearTimeout(timer);
    return false;
}

function getDocElName(){
    return (document.compatMode && document.compatMode == "CSS1Compat") ? "documentElement" : "body";
}