rollmenu = {
    img_prefix   : "btn_",
	img_path     : "img", // path to the images from the site root
    img_ext      : ".gif",   // default extension. all images should have the same extension
    r_img_suffix : "_a",       
    preload : function (file){
      var image = new Image();
      image.src = file;
    },
    s : function(e){
      var el = window.event ? window.event.srcElement : e.currentTarget;
      el.src = el.rollsrc;
    },
    h : function(e){
      var el = window.event ? window.event.srcElement : e.currentTarget;
      el.src = el.defsrc;
    },
    init : function(){
      if (document.images){
        var img_item = r = null;
        var str = rollmenu.img_path+"\\/"+rollmenu.img_prefix+"(\\w+)\\" + rollmenu.img_ext;
        var re = new RegExp(str, "i");
        for (var i = 0; (img_item = document.getElementsByTagName("img").item(i)); i++){
          r = img_item.src.match(re);;
		  if (!r) continue;
            rollmenu.preload(rollmenu.img_path + "/" + rollmenu.img_prefix+r[1]+rollmenu.r_img_suffix+rollmenu.img_ext);
            img_item.rollsrc = rollmenu.img_path + "/" + rollmenu.img_prefix+r[1]+rollmenu.r_img_suffix+rollmenu.img_ext;
            img_item.defsrc = img_item.src;
            rollmenu.l(img_item,"mouseover", rollmenu.s);
            rollmenu.l(img_item,"mouseout", rollmenu.h);
        }
      }
    },
    l : function(o, e, a){
      if (o.addEventListener) return o.addEventListener(e, a, false);
      else if (o.attachEvent) return o.attachEvent("on" + e, a);
      else return false;
    }
}
rollmenu.l(window.addEventListener || window.attachEvent ? window : document.addEventListener ? document : null, "load", rollmenu.init);