var curState = "both";

	function showBoth() {
		if (curState == "new only")
		{	swapClass ("dt_hidden", "deleted_text")
			swapClass ("at_only", "added_text")
		}
		else if (curState == "old only")
		{	swapClass ("dt_only", "deleted_text")
			swapClass ("at_hidden", "added_text")
		}
		curState = "both";
	}

	function showNew() {
		if (curState == "old only")
		{	swapClass ("at_hidden", "at_only")
			swapClass ("dt_only", "dt_hidden")
		}
		else if (curState == "both")
		{	swapClass ("added_text", "at_only")
			swapClass ("deleted_text", "dt_hidden")
		}
		curState = "new only";
	}

	function showOld() {
		if (curState == "new only")
		{	swapClass ("at_only", "at_hidden")
			swapClass ("dt_hidden", "dt_only")
		}
		else if (curState == "both")
		{	swapClass ("added_text", "at_hidden")
			swapClass ("deleted_text", "dt_only")
		}
		curState = "old only";
	}

	function swapClass (oldClass, newClass)
	{	var i;
		var spanList = document.getElementsByTagName ('SPAN');
		for (i = spanList.length - 1; i >= 0; i--)
		{	if (spanList[i].className == oldClass)
				spanList[i].className = newClass;
	}	}