document.movingOne = null;
document.wasDown = false;
document.backScrollTopPosition = 0;
function moveThingsDown()
{
	var thead = document.getElementById('avt_table_thead');
	var tbody = getNextNode(thead);
	var tr = getFirstChild(tbody);
	do
	{
		if(tr.childNodes.length<5)
		{
			if(getScrollTopPosition()<(getTopPosition(tr)-parseInt(getStyle(document.movingOne,'height'))))
			{
				tbody.insertBefore(document.movingOne, tr);
				document.wasDown = true;
				return;
			}
		}
	}
	while((tr=getNextNode(tr))!=null);
}
function moveThingsUp()
{
	var thead = document.getElementById('avt_table_thead');
	thead.appendChild(document.movingOne);
	document.wasDown = false;
	moveThingsDown();
}
window.onscroll = function()
{
	var scrollTopPosition = getScrollTopPosition();
	if(scrollTopPosition != document.backScrollTopPosition)
	{
		if(document.movingOne==null)
		{
			var thead = document.getElementById('avt_table_thead');
			document.movingOne = getFirstChild(thead);
		}
		if(scrollTopPosition>getTopPosition(document.movingOne))	moveThingsDown();
		else if(document.wasDown)									moveThingsUp();
		document.backScrollTopPosition = scrollTopPosition;
	}
}