// JavaScript Document

var timerOn = false;
var isNetscape = (navigator.appName.indexOf("Netscape") >= 0 && parseFloat(navigator.appVersion) >= 4) ? 1 : 0;
var isMSIE = (document.all) ? 1 : 0;

function hideLayer(layer,image) {
   if (isNetscape) document.layers[layer].visibility = "hide";
   if (isMSIE) document.all[layer].style.visibility = "hidden";

   if (document.images) picDown(image);
   }

function showLayer(layer,image) {
   hideAllLayers();
   timerOn=true;
   if (isNetscape) document.layers[layer].visibility = "show";
   if (isMSIE) document.all[layer].style.visibility = "visible";

   if (document.images) picUp(image);
   setTimeout("checkTimer()", 10000)
   }

function hideAllLayers() {
   hideLayer('menu1','link1');
   hideLayer('menu2','link2');
   hideLayer('menu3','link3');
   hideLayer('menu4','link4');

   timerOn=false;
   }

function checkTimer() {
   if (timerOn) hideAllLayers();
   }

if (document.images) {
   link1a = new Image();
   link1a.src = "images/link_1a.gif";

   link1b = new Image();
   link1b.src = "images/link_1b.gif";

   link2a = new Image();
   link2a.src = "images/link_2a.gif";

   link2b = new Image();
   link2b.src = "images/link_2b.gif";

   link3a = new Image();
   link3a.src = "images/link_3a.gif";

   link3b = new Image();
   link3b.src = "images/link_3b.gif";

   link4a = new Image();
   link4a.src = "images/link_4a.gif";

   link4b = new Image();
   link4b.src = "images/link_4b.gif";
   }

function picUp(Image) {
   if (document.images) {
      imgOn = eval(Image + "b.src");
      document [Image].src = imgOn;
      }
   }

function picDown(Image) {
   if (document.images) {
      imgOff = eval(Image + "a.src");
      document [Image].src = imgOff;
      }
   }

function showAnswer(layer,status) {
   if (status == 0) {
      if (isNetscape) document.layers[layer].visibility = "hide";
      if (isMSIE) document.all[layer].style.visibility = "hidden";
      }
   else {
      if (isNetscape) document.layers[layer].visibility = "show";
      if (isMSIE) document.all[layer].style.visibility = "visible";
	  }
   }