var pagesize = 312;
var currentTop = 0;
var targetTop = 0;
var delta_def = 8;
var delta = delta_def;
var moving = false;
var direction = 0;

function scrolldown() {
	if (moving || targetTop >= menu.scrollHeight - pagesize)
		return;
	targetTop += pagesize;
	direction = 0;
	delta = delta_def;
	moving = true;
}
function scrollup() {
	if (moving || targetTop <= 0)
		return;
	targetTop -= pagesize;
	direction = 1;
	delta = delta_def;
	moving = true;
}
function scrolltop() {
	if (moving || targetTop <= 0)
		return;
	targetTop = 0;
	direction = 1;
	delta = delta_def * 2;
	moving = true;
}

function frame() {
	if (currentTop == targetTop)
		return;
	// down
	if (direction == 0) {
		if (currentTop >= targetTop) {
			currentTop = targetTop;
			moving = false;
		}
		else
			currentTop += delta;
	}
	// up
	else {
		if (currentTop <= targetTop) {
			currentTop = targetTop;
			moving = false;
		}
		else
			currentTop -= delta;
	}
	if (Math.abs(targetTop - currentTop) < 100 && delta > 3)
		delta -= 1.3;
	else if (delta < 32)
		delta += 0.5;
	
	menu.scrollTop = currentTop;
}

//window.onload = function() {
	targetTop = pagesize * INIT_PAGE;
	menu = document.getElementById("cmenu");
	menu.scrollTop = currentTop;
	setInterval("frame()", 25);
//}