var stop;

function setup()
{
	document.up_button.src="upbuttonoff.gif";
	disableLoop();
}

function enableLoop()
{
	loop=true;
}

function disableLoop()
{
	loop=false;
}

function scrollUp()
{
	if(loop)
	{
		if(parseInt(document.getElementById('mainLayer').style.top) < 30)
		{
			document.getElementById('mainLayer').style.top = parseInt(document.getElementById('mainLayer').style.top) + 5;
			window.setTimeout("scrollUp()", 1);
			document.down_button.src="downbutton.gif";	
		}
		else
		{
			document.up_button.src="upbuttonoff.gif";
		}
	}
}

function scrollDown()
{
	if(loop)
	{
		if (parseInt(document.getElementById('mainLayer').style.height) + parseInt(document.getElementById('mainLayer').style.top) > 100)
		{
			document.getElementById('mainLayer').style.top = parseInt(document.getElementById('mainLayer').style.top) - 5;
			window.setTimeout("scrollDown()", 1);	
			document.up_button.src="upbutton.gif";		
		}
		else
		{
			document.down_button.src="downbuttonoff.gif";;
		}
	}
}

mainLayer.style.height = document.body.scrollHeight;