var yfmc = {

  init : function() {
     if(!document.getElementsByTagName) {return;}
  },

  addEvent : function(obj, type, func) {
    if (obj.addEventListener) {obj.addEventListener(type, func, false);}
    else if (obj.attachEvent) {
       obj["e" + type + func] = func;
       obj[type + func] = function() {obj["e" + type + func] (window.event);}
       obj.attachEvent("on" + type, obj[type + func]);
    }
    else {obj["on" + type] = func;}
  },
  
  rollovers : function() {
    var holder = document.getElementById('leftnav');
    var theImgs = holder.getElementsByTagName('img');
    var theLinks = holder.getElementsByTagName('a');
    var imgOver = [], imgOff = [], suffix;
    for (var i=0, totalImages = theImgs.length; i<totalImages; i++) {
      if (theImgs[i].id) { continue; }
      suffix = theImgs[i].src.substring(theImgs[i].src.lastIndexOf('.'));
      imgOff[i] = new Image();
      imgOff[i].src = theImgs[i].src;
      imgOver[i] = new Image();
      imgOver[i].src = theImgs[i].src.substring(0,theImgs[i].src.lastIndexOf('.')) + "_over" + suffix;
      theImgs[i].number = i;
      theLinks[i].number = i;
      yfmc.addEvent(theImgs[i],'mouseover', function() { theImgs[this.number].src = imgOver[this.number].src; });
      yfmc.addEvent(theImgs[i],'mouseout', function() { theImgs[this.number].src = imgOff[this.number].src; });     
      yfmc.addEvent(theLinks[i],'focus', function() { theImgs[this.number].src = imgOver[this.number].src; });
      yfmc.addEvent(theLinks[i],'blur', function() { theImgs[this.number].src = imgOff[this.number].src; });
    }
  }
}
yfmc.init();
yfmc.rollovers();