// written by Dean Edwards, 2005
// with input from Tino Zijdel

// http://dean.edwards.name/weblog/2005/10/add-event/

function addEvent(element, type, handler) {
  // assign each event handler a unique ID
  if (!handler.$$guid) handler.$$guid = addEvent.guid++;
  // create a hash table of event types for the element
  if (!element.events) element.events = {};
  // create a hash table of event handlers for each element/event pair
  var handlers = element.events[type];
  if (!handlers) {
    handlers = element.events[type] = {};
    // store the existing event handler (if there is one)
    if (element["on" + type]) {
      handlers[0] = element["on" + type];
    }
  }
  // store the event handler in the hash table
  handlers[handler.$$guid] = handler;
  // assign a global event handler to do all the work
  element["on" + type] = handleEvent;
};
// a counter used to create unique IDs
addEvent.guid = 1;

function removeEvent(element, type, handler) {
  // delete the event handler from the hash table
  if (element.events && element.events[type]) {
    delete element.events[type][handler.$$guid];
  }
};

function handleEvent(event) {
  var returnValue = true;

  // because of other JS libraries that come in and hook our 'onload'
  // function, but don't pass us an argument (for Moz and Safari), we
  // have to do this.

  if (event || window.event) {
    // grab the event object (IE uses a global event object)
    event = event || fixEvent(window.event);
    // get a reference to the hash table of event handlers
    var handlers = this.events[event.type];
	}
  else {
    var handlers = this.events['load'];
    event = null;
  }

  // execute each event handler
  for (var i in handlers) {
    this.$$handleEvent = handlers[i];
    if (this.$$handleEvent(event) === false) {
      returnValue = false;
    }
  }
  return returnValue;
};

function fixEvent(event) {
  // add W3C standard event methods
  event.preventDefault = fixEvent.preventDefault;
  event.stopPropagation = fixEvent.stopPropagation;
  return event;
};
fixEvent.preventDefault = function() {
  this.returnValue = false;
};
fixEvent.stopPropagation = function() {
  this.cancelBubble = true;
};