function listen(imgElm, offSrc, onSrc) {
  // listen for rollovers
  if (imgElm && imgElm.addEventListener) {
    imgElm.addEventListener('mouseover', function (e) {imgElm.src = onSrc;}, false);
    imgElm.addEventListener('mouseout', function (e) {imgElm.src = offSrc;}, false);
  } else if (imgElm && imgElm.attachEvent) {
    imgElm.attachEvent('onmouseover', function (e) {imgElm.src = onSrc;});
    imgElm.attachEvent('onmouseout', function (e) {imgElm.src = offSrc;});
  } else if (imgElm && imgElm.onload) {
    imgElm.onmouseover = function (e) {imgElm.src = onSrc;};
    imgElm.onmouseout = function (e) {imgElm.src = offSrc;};
  }

  // also preload rollover image
  var tmpImg = new Image();
  tmpImg.src = onSrc;
}

function init(e) {
  var imgDir = '/images/layout/';
  listen(getElm('aboutUGL'), imgDir + 'aboutUGL0.gif', imgDir + 'aboutUGL1.gif');
  listen(getElm('howToVideos'), imgDir + 'howToVideos0.gif', imgDir + 'howToVideos1.gif');
  listen(getElm('storeLocator'), imgDir + 'storeLocator0.gif', imgDir + 'storeLocator1.gif');
  listen(getElm('contact'), imgDir + 'contact0.gif', imgDir + 'contact1.gif');
    listen(getElm('dealers'), imgDir + 'dealers0.gif', imgDir + 'dealers1.gif');

  // some product pages may contain pdf links
  var brochureLnk, msdsLnk, ssLnk;
  brochureLnk = getElm('brochure');
  msdsLnk = getElm('msdsSheet');
  ssLnk = getElm('spraySpecs');
  dsLnk = getElm('dataSheet');
  if (brochureLnk) {listen(brochureLnk, imgDir + 'brochure0.gif', imgDir + 'brochure1.gif');}
  if (msdsLnk) {listen(msdsLnk, imgDir + 'msdsSheet0.gif', imgDir + 'msdsSheet1.gif');}
  if (ssLnk) {listen(ssLnk, imgDir + 'spraySpecs0.gif', imgDir + 'spraySpecs1.gif');}
  if (dsLnk) {listen(dsLnk, imgDir + 'dataSheet0.gif', imgDir + 'dataSheet1.gif');}
}

if (window.addEventListener) {
  window.addEventListener('load', init, false);
} else if (window.attachEvent) {
  window.attachEvent('onload', init);
} else if (window.onload) {
  window.onload = init;
}