/olpc/
function initScrolling()
{	
	var scrollElement = document.getElementById("scrollPanel");
	var contentElement = document.getElementById("scrollContent");
	
	if ((scrollElement != null) && (contentElement != null))
	{
		var speed = 8;
		var limitBottom = 0;
		var limitTop = (contentElement.offsetHeight * -1) + scrollElement.offsetHeight;
		
		if (scrollElement.offsetHeight < contentElement.offsetHeight) {			
			document.getElementById("scrollButtons").style.visibility = "visible";	
		}
	}
	
	var upButton = document.getElementById("scrollUp");
	var downButton = document.getElementById("scrollDown");	
	
	if ((upButton != null) && (downButton != null))
	{
		var timerScroller;
		
		upButton.enabledImage = "images/btn_up_enabled.png";
		upButton.disabledImage = "images/btn_up_disabled.png";
	
		downButton.enabledImage = "images/btn_down_enabled.png";
		downButton.disabledImage = "images/btn_down_disabled.png";
		
		upButton.onmousedown = function() {
			timerScroller = setInterval(scrollUp, 100);
		}
		upButton.onmouseup = function() {
			clearInterval(timerScroller);
		}
		upButton.onmouseout = function() {
			clearInterval(timerScroller);
		}
		
		downButton.onmousedown = function() {
			timerScroller = setInterval(scrollDown, 100);
		}
		downButton.onmouseup = function() {
			clearInterval(timerScroller);
		}
		downButton.onmouseout = function() {
			clearInterval(timerScroller);
		}
	}
	
	function scrollUp()
	{
		if (contentElement.offsetTop < limitBottom) {
			contentElement.style.top = contentElement.offsetTop + speed + "px";	
			upButton.src = upButton.enabledImage;		
			downButton.src = downButton.enabledImage;	
		} else {		
			upButton.src = upButton.disabledImage;	
			downButton.src = downButton.enabledImage;		
		}
	}
	
	function scrollDown()
	{
		if (contentElement.offsetTop > limitTop) {
			contentElement.style.top = contentElement.offsetTop - speed + "px";
			downButton.src = downButton.enabledImage;	
			upButton.src = upButton.enabledImage;	
		} else {
			downButton.src = downButton.disabledImage;	
			upButton.src = upButton.enabledImage;					
		}
	}	
}

addOnLoad(initScrolling);