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

function start_scroll_top(el) {
	scorllerInterval = setInterval(function() { scroll_top(el) }, UpdateInterval);
}

function scroll_top(el) {
	document.getElementById(el).scrollTop -= PixelPerInterval;
}


function start_scroll_down(el) {
	scorllerInterval = setInterval(function() { scroll_down(el) }, UpdateInterval);
}

function scroll_down(el) {
	document.getElementById(el).scrollTop += PixelPerInterval;
}


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

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

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

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


function stop_scrolling(el) {
	clearInterval(scorllerInterval);
}