var isIE = document.all?true:false;
	var isNS4 = document.layers?true:false;
	var isNS6 = (document.getElementById && !document.all) ? true : false;
	
	function hideLayer(lay) {
	if (isIE) {document.all[lay].style.visibility = "hidden";}
	if (isNS4) {document.layers[lay].visibility = "hide";}
	if (isNS6) {document.getElementById([lay]).style.visibility = "hidden";}
	}
	
	function showLayer(lay) {
	if (isIE) {document.all[lay].style.visibility = "visible";}
	if (isNS4) {document.layers[lay].visibility = "show";}
	if (isNS6) {document.getElementById([lay]).style.visibility = "visible";}
	}

	function setUpBtn() {
		if (isIE) {
			if (document.body.scrollHeight > document.body.clientHeight) {
				showLayer("up");
			}
			else {
				hideLayer("up");
			}
		}
		if (isNS4 || isNS6) {
			if (document.height > window.innerHeight) {
				showLayer("up");
			}
			else {
				hideLayer("up");
			}
		}
	}