var UpdateInterval = 20;
var PixelPerInterval = 2;
var scorllerInterval;

function start_scroll_right() {
	scorllerInterval = setInterval(scroll_left, UpdateInterval);
}

function scroll_right() {
	document.getElementById('scroller').scrollLeft -= PixelPerInterval;
}

function start_scroll_left() {
	scorllerInterval = setInterval(scroll_right, UpdateInterval);
}

function scroll_left() {
	document.getElementById('scroller').scrollLeft += PixelPerInterval;
}

function stop_scrolling() {
	clearInterval(scorllerInterval);
}