PageLoadingEventHandler = Class.create();
PageLoadingEventHandler.prototype =
{
    initialize: function() {
        this.queue = $A();
        this.eventQueue = $A();
        this.waitFor('html');

    },
    waitFor: function(what) {
        this.queue[this.queue.size()] = what;
    },
    loaded: function(what) {
        // OK, handle newer version of prototype ..
        this.queue = this.queue.without(what);

        if (this.queue.size() == 0)
            this._onComplete();

    },
    doLoad: function() {
        this.loaded('html');
    },
    registerOnComplete: function(prio, handler) {
        this.eventQueue[this.eventQueue.size()] = new OnHandlerEntry(prio, handler);
    },
    _onComplete: function() {
        // OK, everything is loaded and initialized,
        // lets dispatch our handlers as well..
        this.eventQueue.sort(this._prioSort);

        var num = this.eventQueue.size();

        for (var i = 0; i < num; i++) {
            var obj = this.eventQueue[i];

            if (obj) {
                var f = obj.handler;
                f();
            }
        }
    },
    _prioSort: function(a, b) {
        if (a.prio > b.prio)
            return 1;
        else
            return -1;
    }
};

function OnHandlerEntry(prio,handler)
{
    this.prio = prio;
    this.handler = handler;
}

var PageLoading = null;

function loaded(what)
{
  PageLoading.loaded(what);
}
function waitFor(what) {

  if(PageLoading == null)
  {
    PageLoading = new PageLoadingEventHandler();
    Event.observe(window, 'load',PageLoading.doLoad.bind(PageLoading));
  }
  PageLoading.waitFor(what);
}

function registerOnComplete(prio,handler) {

  if(PageLoading == null)
  {
    PageLoading = new PageLoadingEventHandler();
    Event.observe(window, 'load',PageLoading.doLoad.bind(PageLoading));
  }
  PageLoading.registerOnComplete(prio,handler);
}