var i=0;
var scroll_break=1;
var setTimer = null;

function scroll_up(obj){
    if (i>=20)
        i=i-20;
    else if (i<20 && i>=0)
        i=0;
    document.getElementById(obj).scrollTop=i;
    if (scroll_break) {
		clearTimeout( setTimer );
        setTimer = setTimeout('scroll_up("' + obj + '");', 100);
	} else {
        scroll_break=1;
	}
}

function scroll_down(obj){
    var scroll=document.getElementById(obj).scrollTop;
    if ((i-5)<=scroll)
        i=i+20;
    else if ((i-5)>scroll)
        i=scroll;
    document.getElementById(obj).scrollTop=i;
    if (scroll_break) {
		clearTimeout( setTimer );
        setTimer = setTimeout('scroll_down("' + obj + '");', 100);
	} else {
        scroll_break=1;
	}
}

function scroll_breaker(){
    scroll_break = 0;
	clearTimeout( setTimer );
}