// addEvent/removeEvent 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;
          // 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];
          // 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;
  };