function showTopLayer(id) {
	if (!document.getElementById("topLayerBg")) {
		var topLayerBg = document.createElement("div");
		topLayerBg.id = "topLayerBg";
		document.body.appendChild(topLayerBg);
		
		var topLayer = document.getElementById(id);
		
		var selects = document.getElementsByTagName("select");
		var ie = navigator.appName == "Microsoft Internet Explorer";
		
		if (ie) {
			for (i=0; i<selects.length; i++) {selects[i].style.visibility = "hidden";}
		}
		
		if (self.pageYOffset) {topPos = self.pageYOffset;}
		else if (document.documentElement && document.documentElement.scrollTop) {topPos = document.documentElement.scrollTop;}
		else if (document.body) {topPos = document.body.scrollTop;}
		
		if (self.innerHeight) {sizeY = self.innerHeight;}
		else if (document.documentElement && document.documentElement.clientHeight) {sizeY = document.documentElement.clientHeight;}
		else if (document.body) {sizeY = document.body.clientHeight;}
		
		if (window.innerHeight && window.scrollMaxY) {sizeYoverall = window.innerHeight + window.scrollMaxY;}
		else if (document.body.scrollHeight > document.body.offsetHeight){sizeYoverall = document.body.scrollHeight;}
		else {sizeYoverall = document.body.offsetHeight;}
		
		if(sizeYoverall < sizeY) {pHeight = sizeY;}
		else {pHeight = sizeYoverall;}
		
		topLayer.style.display = "block";
		
		topLayer.style.top = topPos + sizeY/2 - topLayer.offsetHeight/2 + "px";
		topLayerBg.style.height = pHeight + "px";
	}
}

function hideTopLayer(obj) {
	var topLayerBg = document.getElementById("topLayerBg");
	var topLayer = obj.parentNode.parentNode;
	topLayerBg.parentNode.removeChild(topLayerBg);
	topLayer.style.display = "none";
	
	if (navigator.appName == "Microsoft Internet Explorer") {
		var selects = document.getElementsByTagName("select");
		for (i=0; i<selects.length; i++) {selects[i].style.visibility = "visible";}
	}
}