function addEvent( obj, type, fn ){
  if (obj.addEventListener)
    obj.addEventListener( type, fn, false );
  else if (obj.attachEvent) {
    obj["e"+type+fn] = fn;
    obj[type+fn] = function() { obj["e"+type+fn]( window.event ); }
    obj.attachEvent( "on"+type, obj[type+fn] );
  }
}

function numSort (a,b){
  return a-b;
}

function imageReplace(obj,replace){
  var type=obj.getAttribute('className');
  if (type==null) type=obj.getAttribute('class');
  obj.src=eval(type+ "_" +replace +".src");
}


function getElementsByClassName(strClass, strTag, objContElm) {
  strTag = strTag || "*";
  objContElm = objContElm || document;
  var objColl = objContElm.getElementsByTagName(strTag);
  if (!objColl.length &&  strTag == "*" &&  objContElm.all) objColl = objContElm.all;
  var arr = new Array();
  var delim = strClass.indexOf('|') != -1  ? '|' : ' ';
  var arrClass = strClass.split(delim);
  for (var i = 0, j = objColl.length; i < j; i++) {
    var arrObjClass = objColl[i].className.split(' ');
    if (delim == ' ' && arrClass.length > arrObjClass.length) continue;
    var c = 0;
    comparisonLoop:
    for (var k = 0, l = arrObjClass.length; k < l; k++) {
      for (var m = 0, n = arrClass.length; m < n; m++) {
        if (arrClass[m] == arrObjClass[k]) c++;
        if (( delim == '|' && c == 1) || (delim == ' ' && c == arrClass.length)) {
          arr.push(objColl[i]);
          break comparisonLoop;
        }
      }
    }
  }
  return arr;
}

// To cover IE 5.0's lack of the push method
Array.prototype.push = function(value) {
  this[this.length] = value;
}


function rolloverWalk(list){
   for (var i=0; i < list.length; ++i){
     
     var image=list[i];
     addEvent(image, 'mouseout', function(){imageReplace(this,'mouseout');});
     addEvent(image, 'mouseover', function(){imageReplace(this,'mouseover');});
   }
}

function rolloverInit(){
  var container=document.getElementById('container');
  var nexts=getElementsByClassName('next','img',container);
  var prevs=getElementsByClassName('previous','img',container);
  rolloverWalk(nexts);
  rolloverWalk(prevs);  
}




var next_mouseout=new Image();
next_mouseout.src='/img/nav/next.gif';
var next_mouseover=new Image();
next_mouseover.src='/img/nav/next-over.gif';
var previous_mouseout=new Image();
previous_mouseout.src='/img/nav/previous.gif';
var previous_mouseover=new Image();
previous_mouseover.src='/img/nav/previous-over.gif';

addEvent(window,'load',rolloverInit);