okay = false;  

var preload = new Array ( "images/blank.gif", "images/foobg.gif", "images/foon.gif", "images/lcolor.gif", "images/lgray.gif" );

with(navigator) {
  code = appCodeName;
  app = appName;
  version = appVersion;
  iver = parseInt(version);
  ua = userAgent;
  }

if ( code == "Mozilla" && iver >= 3 )  okay = true;
else { okay = false; }

if(okay) {

  var re = new RegExp();
  re.compile("[\\/.:\\-\\s]", "g");

  for (var i = 0; i < preload.length; i++) {
    i_preload(preload[i]);
    }
  var preloaded = true
  }

function iname (img)
{
var s = img.replace(re, "_");
return s;
}

function i_preload(img)
{
if(img) {
  var imgn = iname(img);
  eval(imgn + " = new Image()");
  eval(imgn + ".src = '" + img + "'");
  }
return true;
}

function on (name)
{
if(!okay) return true; 

if(preloaded) document.getElementById(name).style.backgroundImage = "url(images/foobg.gif)";
return true;
}

function off (name)
{
if(!okay) return true; 

if(preloaded) document.getElementById(name).style.backgroundImage = "url(images/foon.gif)";
return true;
}

function onlog (name)
{
if(!okay) return true; 

if(preloaded) document.getElementById(name).style.backgroundImage = "url(images/lcolor.gif)";
return true;
}

function offlog (name)
{
if(!okay) return true; 

if(preloaded) document.getElementById(name).style.backgroundImage = "url(images/lgray.gif)";
return true;
}