/* Prototype JavaScript framework, version 1.5.0_rc1
 * (c) 2005 Sam Stephenson <sam@conio.net>
 *
 * Prototype is freely distributable under the terms of an MIT-style license.
 * For details, see the Prototype web site: http://prototype.conio.net/
 *
/*--------------------------------------------------------------------------*/

var Prototype = {
 Version: '1.5.0_rc1',
 ScriptFragment: '(?:<script.*?>)((\n|\r|.)*?)(?:<\/script>)',

 emptyFunction: function() {},
 K: function(x) {return x}
}

var Class = {
 create: function() {
  return function() {
   this.initialize.apply(this, arguments);
  }
 }
}

var Abstract = new Object();

Object.extend = function(destination, source) {
 for (var property in source) {
  destination[property] = source[property];
 }
 return destination;
}

Object.extend(Object, {
 inspect: function(object) {
  try {
   if (object == undefined) return 'undefined';
   if (object == null) return 'null';
   return object.inspect ? object.inspect() : object.toString();
  } catch (e) {
   if (e instanceof RangeError) return '...';
   throw e;
  }
 },

 keys: function(object) {
  var keys = [];
  for (var property in object)
   keys.push(property);
  return keys;
 },

 values: function(object) {
  var values = [];
  for (var property in object)
   values.push(object[property]);
  return values;
 },

 clone: function(object) {
  return Object.extend({}, object);
 }
});

Function.prototype.bind = function() {
 var __method = this, args = $A(arguments), object = args.shift();
 return function() {
  return __method.apply(object, args.concat($A(arguments)));
 }
}

Function.prototype.bindAsEventListener = function(object) {
 var __method = this, args = $A(arguments), object = args.shift();
 return function(event) {
  return __method.apply(object, [( event || window.event)].concat(args).concat($A(arguments)));
 }
}

Object.extend(Number.prototype, {
 toColorPart: function() {
  var digits = this.toString(16);
  if (this < 16) return '0' + digits;
  return digits;
 },

 succ: function() {
  return this + 1;
 },

 times: function(iterator) {
  $R(0, this, true).each(iterator);
  return this;
 }
});

var Try = {
 these: function() {
  var returnValue;

  for (var i = 0; i < arguments.length; i++) {
   var lambda = arguments[i];
   try {
    returnValue = lambda();
    break;
   } catch (e) {}
  }

  return returnValue;
 }
}

/*--------------------------------------------------------------------------*/

var PeriodicalExecuter = Class.create();
PeriodicalExecuter.prototype = {
 initialize: function(callback, frequency) {
  this.callback = callback;
  this.frequency = frequency;
  this.currentlyExecuting = false;

  this.registerCallback();
 },

 registerCallback: function() {
  this.timer = setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
 },

 stop: function() {
  if (!this.timer) return;
  clearInterval(this.timer);
  this.timer = null;
 },

 onTimerEvent: function() {
  if (!this.currentlyExecuting) {
   try {
    this.currentlyExecuting = true;
    this.callback(this);
   } finally {
    this.currentlyExecuting = false;
   }
  }
 }
}
Object.extend(String.prototype, {
 gsub: function(pattern, replacement) {
  var result = '', source = this, match;
  replacement = arguments.callee.prepareReplacement(replacement);

  while (source.length > 0) {
   if (match = source.match(pattern)) {
    result += source.slice(0, match.index);
    result += (replacement(match) || '').toString();
    source = source.slice(match.index + match[0].length);
   } else {
    result += source, source = '';
   }
  }
  return result;
 },

 sub: function(pattern, replacement, count) {
  replacement = this.gsub.prepareReplacement(replacement);
  count = count === undefined ? 1 : count;

  return this.gsub(pattern, function(match) {
   if (--count < 0) return match[0];
   return replacement(match);
  });
 },

 scan: function(pattern, iterator) {
  this.gsub(pattern, iterator);
  return this;
 },

 truncate: function(length, truncation) {
  length = length || 30;
  truncation = truncation === undefined ? '...' : truncation;
  return this.length > length ?
   this.slice(0, length - truncation.length) + truncation : this;
 },

 strip: function() {
  return this.replace(/^\s+/, '').replace(/\s+$/, '');
 },

 stripTags: function() {
  return this.replace(/<\/?[^>]+>/gi, '');
 },

 stripScripts: function() {
  return this.replace(new RegExp(Prototype.ScriptFragment, 'img'), '');
 },

 extractScripts: function() {
  var matchAll = new RegExp(Prototype.ScriptFragment, 'img');
  var matchOne = new RegExp(Prototype.ScriptFragment, 'im');
  return (this.match(matchAll) || []).map(function(scriptTag) {
   return (scriptTag.match(matchOne) || ['', ''])[1];
  });
 },

 evalScripts: function() {
  return this.extractScripts().map(function(script) { return eval(script) });
 },

 escapeHTML: function() {
  var div = document.createElement('div');
  var text = document.createTextNode(this);
  div.appendChild(text);
  return div.innerHTML;
 },

 unescapeHTML: function() {
  var div = document.createElement('div');
  div.innerHTML = this.stripTags();
  return div.childNodes[0] ? div.childNodes[0].nodeValue : '';
 },

 toQueryParams: function() {
  var pairs = this.match(/^\??(.*)$/)[1].split('&');
  return pairs.inject({}, function(params, pairString) {
   var pair = pairString.split('=');
   var value = pair[1] ? decodeURIComponent(pair[1]) : undefined;
   params[decodeURIComponent(pair[0])] = value;
   return params;
  });
 },

 toArray: function() {
  return this.split('');
 },

 camelize: function() {
  var oStringList = this.split('-');
  if (oStringList.length == 1) return oStringList[0];

  var camelizedString = this.indexOf('-') == 0
   ? oStringList[0].charAt(0).toUpperCase() + oStringList[0].substring(1)
   : oStringList[0];

  for (var i = 1, len = oStringList.length; i < len; i++) {
   var s = oStringList[i];
   camelizedString += s.charAt(0).toUpperCase() + s.substring(1);
  }

  return camelizedString;
 },

 inspect: function(useDoubleQuotes) {
  var escapedString = this.replace(/\\/g, '\\\\');
  if (useDoubleQuotes)
   return '"' + escapedString.replace(/"/g, '\\"') + '"';
  else
   return "'" + escapedString.replace(/'/g, '\\\'') + "'";
 }
});

String.prototype.gsub.prepareReplacement = function(replacement) {
 if (typeof replacement == 'function') return replacement;
 var template = new Template(replacement);
 return function(match) { return template.evaluate(match) };
}

String.prototype.parseQuery = String.prototype.toQueryParams;

var Template = Class.create();
Template.Pattern = /(^|.|\r|\n)(#\{(.*?)\})/;
Template.prototype = {
 initialize: function(template, pattern) {
  this.template = template.toString();
  this.pattern = pattern || Template.Pattern;
 },

 evaluate: function(object) {
  return this.template.gsub(this.pattern, function(match) {
   var before = match[1];
   if (before == '\\') return match[2];
   return before + (object[match[3]] || '').toString();
  });
 }
}

var $break  = new Object();
var $continue = new Object();

var Enumerable = {
 each: function(iterator) {
  var index = 0;
  try {
   this._each(function(value) {
    try {
     iterator(value, index++);
    } catch (e) {
     if (e != $continue) throw e;
    }
   });
  } catch (e) {
   if (e != $break) throw e;
  }
 },

 all: function(iterator) {
  var result = true;
  this.each(function(value, index) {
   result = result && !!(iterator || Prototype.K)(value, index);
   if (!result) throw $break;
  });
  return result;
 },

 any: function(iterator) {
  var result = false;
  this.each(function(value, index) {
   if (result = !!(iterator || Prototype.K)(value, index))
    throw $break;
  });
  return result;
 },

 collect: function(iterator) {
  var results = [];
  this.each(function(value, index) {
   results.push(iterator(value, index));
  });
  return results;
 },

 detect: function (iterator) {
  var result;
  this.each(function(value, index) {
   if (iterator(value, index)) {
    result = value;
    throw $break;
   }
  });
  return result;
 },

 findAll: function(iterator) {
  var results = [];
  this.each(function(value, index) {
   if (iterator(value, index))
    results.push(value);
  });
  return results;
 },

 grep: function(pattern, iterator) {
  var results = [];
  this.each(function(value, index) {
   var stringValue = value.toString();
   if (stringValue.match(pattern))
    results.push((iterator || Prototype.K)(value, index));
  })
  return results;
 },

 include: function(object) {
  var found = false;
  this.each(function(value) {
   if (value == object) {
    found = true;
    throw $break;
   }
  });
  return found;
 },

 inject: function(memo, iterator) {
  this.each(function(value, index) {
   memo = iterator(memo, value, index);
  });
  return memo;
 },

 invoke: function(method) {
  var args = $A(arguments).slice(1);
  return this.collect(function(value) {
   return value[method].apply(value, args);
  });
 },

 max: function(iterator) {
  var result;
  this.each(function(value, index) {
   value = (iterator || Prototype.K)(value, index);
   if (result == undefined || value >= result)
    result = value;
  });
  return result;
 },

 min: function(iterator) {
  var result;
  this.each(function(value, index) {
   value = (iterator || Prototype.K)(value, index);
   if (result == undefined || value < result)
    result = value;
  });
  return result;
 },

 partition: function(iterator) {
  var trues = [], falses = [];
  this.each(function(value, index) {
   ((iterator || Prototype.K)(value, index) ?
    trues : falses).push(value);
  });
  return [trues, falses];
 },

 pluck: function(property) {
  var results = [];
  this.each(function(value, index) {
   results.push(value[property]);
  });
  return results;
 },

 reject: function(iterator) {
  var results = [];
  this.each(function(value, index) {
   if (!iterator(value, index))
    results.push(value);
  });
  return results;
 },

 sortBy: function(iterator) {
  return this.collect(function(value, index) {
   return {value: value, criteria: iterator(value, index)};
  }).sort(function(left, right) {
   var a = left.criteria, b = right.criteria;
   return a < b ? -1 : a > b ? 1 : 0;
  }).pluck('value');
 },

 toArray: function() {
  return this.collect(Prototype.K);
 },

 zip: function() {
  var iterator = Prototype.K, args = $A(arguments);
  if (typeof args.last() == 'function')
   iterator = args.pop();

  var collections = [this].concat(args).map($A);
  return this.map(function(value, index) {
   return iterator(collections.pluck(index));
  });
 },

 inspect: function() {
  return '#<Enumerable:' + this.toArray().inspect() + '>';
 }
}

Object.extend(Enumerable, {
 map:   Enumerable.collect,
 find:  Enumerable.detect,
 select: Enumerable.findAll,
 member: Enumerable.include,
 entries: Enumerable.toArray
});
var $A = Array.from = function(iterable) {
 if (!iterable) return [];
 if (iterable.toArray) {
  return iterable.toArray();
 } else {
  var results = [];
  for (var i = 0; i < iterable.length; i++)
   results.push(iterable[i]);
  return results;
 }
}

Object.extend(Array.prototype, Enumerable);

if (!Array.prototype._reverse)
 Array.prototype._reverse = Array.prototype.reverse;

Object.extend(Array.prototype, {
 _each: function(iterator) {
  for (var i = 0; i < this.length; i++)
   iterator(this[i]);
 },

 clear: function() {
  this.length = 0;
  return this;
 },

 first: function() {
  return this[0];
 },

 last: function() {
  return this[this.length - 1];
 },

 compact: function() {
  return this.select(function(value) {
   return value != undefined || value != null;
  });
 },

 flatten: function() {
  return this.inject([], function(array, value) {
   return array.concat(value && value.constructor == Array ?
    value.flatten() : [value]);
  });
 },

 without: function() {
  var values = $A(arguments);
  return this.select(function(value) {
   return !values.include(value);
  });
 },

 indexOf: function(object) {
  for (var i = 0; i < this.length; i++)
   if (this[i] == object) return i;
  return -1;
 },

 reverse: function(inline) {
  return (inline !== false ? this : this.toArray())._reverse();
 },

 reduce: function() {
  return this.length > 1 ? this : this[0];
 },

 uniq: function() {
  return this.inject([], function(array, value) {
   return array.include(value) ? array : array.concat([value]);
  });
 },

 inspect: function() {
  return '[' + this.map(Object.inspect).join(', ') + ']';
 }
});
var Hash = {
 _each: function(iterator) {
  for (var key in this) {
   var value = this[key];
   if (typeof value == 'function') continue;

   var pair = [key, value];
   pair.key = key;
   pair.value = value;
   iterator(pair);
  }
 },

 keys: function() {
  return this.pluck('key');
 },

 values: function() {
  return this.pluck('value');
 },

 merge: function(hash) {
  return $H(hash).inject($H(this), function(mergedHash, pair) {
   mergedHash[pair.key] = pair.value;
   return mergedHash;
  });
 },

 toQueryString: function() {
  return this.map(function(pair) {
   return pair.map(encodeURIComponent).join('=');
  }).join('&');
 },

 inspect: function() {
  return '#<Hash:{' + this.map(function(pair) {
   return pair.map(Object.inspect).join(': ');
  }).join(', ') + '}>';
 }
}

function $H(object) {
 var hash = Object.extend({}, object || {});
 Object.extend(hash, Enumerable);
 Object.extend(hash, Hash);
 return hash;
}
ObjectRange = Class.create();
Object.extend(ObjectRange.prototype, Enumerable);
Object.extend(ObjectRange.prototype, {
 initialize: function(start, end, exclusive) {
  this.start = start;
  this.end = end;
  this.exclusive = exclusive;
 },

 _each: function(iterator) {
  var value = this.start;
  while (this.include(value)) {
   iterator(value);
   value = value.succ();
  }
 },

 include: function(value) {
  if (value < this.start)
   return false;
  if (this.exclusive)
   return value < this.end;
  return value <= this.end;
 }
});

var $R = function(start, end, exclusive) {
 return new ObjectRange(start, end, exclusive);
}

var Ajax = {
 getTransport: function() {
  return Try.these(
   function() {return new XMLHttpRequest()},
   function() {return new ActiveXObject('Msxml2.XMLHTTP')},
   function() {return new ActiveXObject('Microsoft.XMLHTTP')}
  ) || false;
 },

 activeRequestCount: 0
}

Ajax.Responders = {
 responders: [],

 _each: function(iterator) {
  this.responders._each(iterator);
 },

 register: function(responderToAdd) {
  if (!this.include(responderToAdd))
   this.responders.push(responderToAdd);
 },

 unregister: function(responderToRemove) {
  this.responders = this.responders.without(responderToRemove);
 },

 dispatch: function(callback, request, transport, json) {
  this.each(function(responder) {
   if (responder[callback] && typeof responder[callback] == 'function') {
    try {
     responder[callback].apply(responder, [request, transport, json]);
    } catch (e) {}
   }
  });
 }
};

Object.extend(Ajax.Responders, Enumerable);

Ajax.Responders.register({
 onCreate: function() {
  Ajax.activeRequestCount++;
 },

 onComplete: function() {
  Ajax.activeRequestCount--;
 }
});

Ajax.Base = function() {};
Ajax.Base.prototype = {
 setOptions: function(options) {
  this.options = {
   method:    'post',
   asynchronous: true,
   contentType: 'application/x-www-form-urlencoded',
   parameters:  ''
  }
  Object.extend(this.options, options || {});
 },

 responseIsSuccess: function() {
  return this.transport.status == undefined
    || this.transport.status == 0
    || (this.transport.status >= 200 && this.transport.status < 300);
 },

 responseIsFailure: function() {
  return !this.responseIsSuccess();
 }
}

Ajax.Request = Class.create();
Ajax.Request.Events =
 ['Uninitialized', 'Loading', 'Loaded', 'Interactive', 'Complete'];

Ajax.Request.prototype = Object.extend(new Ajax.Base(), {
 initialize: function(url, options) {
  this.transport = Ajax.getTransport();
  this.setOptions(options);
  this.request(url);
 },

 request: function(url) {
  var parameters = this.options.parameters || '';
  if (parameters.length > 0) parameters += '&_=';

  /* Simulate other verbs over post */
  if (this.options.method != 'get' && this.options.method != 'post') {
   parameters += (parameters.length > 0 ? '&' : '') + '_method=' + this.options.method;
   this.options.method = 'post';
  }

  try {
   this.url = url;
   if (this.options.method == 'get' && parameters.length > 0)
    this.url += (this.url.match(/\?/) ? '&' : '?') + parameters;

   Ajax.Responders.dispatch('onCreate', this, this.transport);

   this.transport.open(this.options.method, this.url,
    this.options.asynchronous);

   if (this.options.asynchronous)
    setTimeout(function() { this.respondToReadyState(1) }.bind(this), 10);

   this.transport.onreadystatechange = this.onStateChange.bind(this);
   this.setRequestHeaders();

   var body = this.options.postBody ? this.options.postBody : parameters;
   this.transport.send(this.options.method == 'post' ? body : null);

   /* Force Firefox to handle ready state 4 for synchronous requests */
   if (!this.options.asynchronous && this.transport.overrideMimeType)
    this.onStateChange();

  } catch (e) {
   this.dispatchException(e);
  }
 },

 setRequestHeaders: function() {
  var requestHeaders =
   ['X-Requested-With', 'XMLHttpRequest',
    'X-Prototype-Version', Prototype.Version,
    'Accept', 'text/javascript, text/html, application/xml, text/xml, */*'];

  if (this.options.method == 'post') {
   requestHeaders.push('Content-type', this.options.contentType);

   /* Force "Connection: close" for Mozilla browsers to work around
    * a bug where XMLHttpReqeuest sends an incorrect Content-length
    * header. See Mozilla Bugzilla #246651.
    */
   if (this.transport.overrideMimeType)
    requestHeaders.push('Connection', 'close');
  }

  if (this.options.requestHeaders)
   requestHeaders.push.apply(requestHeaders, this.options.requestHeaders);

  for (var i = 0; i < requestHeaders.length; i += 2)
   this.transport.setRequestHeader(requestHeaders[i], requestHeaders[i+1]);
 },

 onStateChange: function() {
  var readyState = this.transport.readyState;
  if (readyState != 1)
   this.respondToReadyState(this.transport.readyState);
 },

 header: function(name) {
  try {
   return this.transport.getResponseHeader(name);
  } catch (e) {}
 },

 evalJSON: function() {
  try {
   return eval('(' + this.header('X-JSON') + ')');
  } catch (e) {}
 },

 evalResponse: function() {
  try {
   return eval(this.transport.responseText);
  } catch (e) {
   this.dispatchException(e);
  }
 },

 respondToReadyState: function(readyState) {
  var event = Ajax.Request.Events[readyState];
  var transport = this.transport, json = this.evalJSON();

  if (event == 'Complete') {
   try {
    (this.options['on' + this.transport.status]
     || this.options['on' + (this.responseIsSuccess() ? 'Success' : 'Failure')]
     || Prototype.emptyFunction)(transport, json);
   } catch (e) {
    this.dispatchException(e);
   }

   if ((this.header('Content-type') || '').match(/^text\/javascript/i))
    this.evalResponse();
  }

  try {
   (this.options['on' + event] || Prototype.emptyFunction)(transport, json);
   Ajax.Responders.dispatch('on' + event, this, transport, json);
  } catch (e) {
   this.dispatchException(e);
  }

  /* Avoid memory leak in MSIE: clean up the oncomplete event handler */
  if (event == 'Complete')
   this.transport.onreadystatechange = Prototype.emptyFunction;
 },

 dispatchException: function(exception) {
  (this.options.onException || Prototype.emptyFunction)(this, exception);
  Ajax.Responders.dispatch('onException', this, exception);
 }
});

Ajax.Updater = Class.create();

Object.extend(Object.extend(Ajax.Updater.prototype, Ajax.Request.prototype), {
 initialize: function(container, url, options) {
  this.containers = {
   success: container.success ? $(container.success) : $(container),
   failure: container.failure ? $(container.failure) :
    (container.success ? null : $(container))
  }

  this.transport = Ajax.getTransport();
  this.setOptions(options);

  var onComplete = this.options.onComplete || Prototype.emptyFunction;
  this.options.onComplete = (function(transport, object) {
   this.updateContent();
   onComplete(transport, object);
  }).bind(this);

  this.request(url);
 },

 updateContent: function() {
  var receiver = this.responseIsSuccess() ?
   this.containers.success : this.containers.failure;
  var response = this.transport.responseText;

  if (!this.options.evalScripts)
   response = response.stripScripts();

  if (receiver) {
   if (this.options.insertion) {
    new this.options.insertion(receiver, response);
   } else {
    Element.update(receiver, response);
   }
  }

  if (this.responseIsSuccess()) {
   if (this.onComplete)
    setTimeout(this.onComplete.bind(this), 10);
  }
 }
});

Ajax.PeriodicalUpdater = Class.create();
Ajax.PeriodicalUpdater.prototype = Object.extend(new Ajax.Base(), {
 initialize: function(container, url, options) {
  this.setOptions(options);
  this.onComplete = this.options.onComplete;

  this.frequency = (this.options.frequency || 2);
  this.decay = (this.options.decay || 1);

  this.updater = {};
  this.container = container;
  this.url = url;

  this.start();
 },

 start: function() {
  this.options.onComplete = this.updateComplete.bind(this);
  this.onTimerEvent();
 },

 stop: function() {
  this.updater.options.onComplete = undefined;
  clearTimeout(this.timer);
  (this.onComplete || Prototype.emptyFunction).apply(this, arguments);
 },

 updateComplete: function(request) {
  if (this.options.decay) {
   this.decay = (request.responseText == this.lastText ?
    this.decay * this.options.decay : 1);

   this.lastText = request.responseText;
  }
  this.timer = setTimeout(this.onTimerEvent.bind(this),
   this.decay * this.frequency * 1000);
 },

 onTimerEvent: function() {
  this.updater = new Ajax.Updater(this.container, this.url, this.options);
 }
});
function $() {
 var results = [], element;
 for (var i = 0; i < arguments.length; i++) {
  element = arguments[i];
  if (typeof element == 'string')
   element = document.getElementById(element);
  results.push(Element.extend(element));
 }
 return results.reduce();
}

document.getElementsByClassName = function(className, parentElement) {
 var children = ($(parentElement) || document.body).getElementsByTagName('*');
 return $A(children).inject([], function(elements, child) {
  if (child.className.match(new RegExp("(^|\\s)" + className + "(\\s|$)")))
   elements.push(Element.extend(child));
  return elements;
 });
}

/*--------------------------------------------------------------------------*/

if (!window.Element)
 var Element = new Object();

Element.extend = function(element) {
 if (!element) return;
 if (_nativeExtensions || element.nodeType == 3) return element;

 if (!element._extended && element.tagName && element != window) {
  var methods = Object.clone(Element.Methods), cache = Element.extend.cache;

  if (element.tagName == 'FORM')
   Object.extend(methods, Form.Methods);
  if (['INPUT', 'TEXTAREA', 'SELECT'].include(element.tagName))
   Object.extend(methods, Form.Element.Methods);

  for (var property in methods) {
   var value = methods[property];
   if (typeof value == 'function')
    element[property] = cache.findOrStore(value);
  }
 }

 element._extended = true;
 return element;
}

Element.extend.cache = {
 findOrStore: function(value) {
  return this[value] = this[value] || function() {
   return value.apply(null, [this].concat($A(arguments)));
  }
 }
}

Element.Methods = {
 visible: function(element) {
  return $(element).style.display != 'none';
 },

 toggle: function(element) {
  element = $(element);
  Element[Element.visible(element) ? 'hide' : 'show'](element);
  return element;
 },

 hide: function(element) {
  $(element).style.display = 'none';
  return element;
 },

 show: function(element) {
  $(element).style.display = '';
  return element;
 },

 remove: function(element) {
  element = $(element);
  element.parentNode.removeChild(element);
  return element;
 },

 update: function(element, html) {
  $(element).innerHTML = html.stripScripts();
  setTimeout(function() {html.evalScripts()}, 10);
  return element;
 },

 replace: function(element, html) {
  element = $(element);
  if (element.outerHTML) {
   element.outerHTML = html.stripScripts();
  } else {
   var range = element.ownerDocument.createRange();
   range.selectNodeContents(element);
   element.parentNode.replaceChild(
    range.createContextualFragment(html.stripScripts()), element);
  }
  setTimeout(function() {html.evalScripts()}, 10);
  return element;
 },

 inspect: function(element) {
  element = $(element);
  var result = '<' + element.tagName.toLowerCase();
  $H({'id': 'id', 'className': 'class'}).each(function(pair) {
   var property = pair.first(), attribute = pair.last();
   var value = (element[property] || '').toString();
   if (value) result += ' ' + attribute + '=' + value.inspect(true);
  });
  return result + '>';
 },

 recursivelyCollect: function(element, property) {
  element = $(element);
  var elements = [];
  while (element = element[property])
   if (element.nodeType == 1)
    elements.push(Element.extend(element));
  return elements;
 },

 ancestors: function(element) {
  return $(element).recursivelyCollect('parentNode');
 },

 descendants: function(element) {
  element = $(element);
  return $A(element.getElementsByTagName('*'));
 },

 previousSiblings: function(element) {
  return $(element).recursivelyCollect('previousSibling');
 },

 nextSiblings: function(element) {
  return $(element).recursivelyCollect('nextSibling');
 },

 siblings: function(element) {
  element = $(element);
  return element.previousSiblings().reverse().concat(element.nextSiblings());
 },

 match: function(element, selector) {
  element = $(element);
  if (typeof selector == 'string')
   selector = new Selector(selector);
  return selector.match(element);
 },

 up: function(element, expression, index) {
  return Selector.findElement($(element).ancestors(), expression, index);
 },

 down: function(element, expression, index) {
  return Selector.findElement($(element).descendants(), expression, index);
 },

 previous: function(element, expression, index) {
  return Selector.findElement($(element).previousSiblings(), expression, index);
 },

 next: function(element, expression, index) {
  return Selector.findElement($(element).nextSiblings(), expression, index);
 },

 getElementsBySelector: function() {
  var args = $A(arguments), element = $(args.shift());
  return Selector.findChildElements(element, args);
 },

 getElementsByClassName: function(element, className) {
  element = $(element);
  return document.getElementsByClassName(className, element);
 },

 getHeight: function(element) {
  element = $(element);
  return element.offsetHeight;
 },

 classNames: function(element) {
  return new Element.ClassNames(element);
 },

 hasClassName: function(element, className) {
  if (!(element = $(element))) return;
  return Element.classNames(element).include(className);
 },

 addClassName: function(element, className) {
  if (!(element = $(element))) return;
  Element.classNames(element).add(className);
  return element;
 },

 removeClassName: function(element, className) {
  if (!(element = $(element))) return;
  Element.classNames(element).remove(className);
  return element;
 },

 observe: function() {
  Event.observe.apply(Event, arguments);
  return $A(arguments).first();
 },

 stopObserving: function() {
  Event.stopObserving.apply(Event, arguments);
  return $A(arguments).first();
 },

 // removes whitespace-only text node children
 cleanWhitespace: function(element) {
  element = $(element);
  var node = element.firstChild;
  while (node) {
   var nextNode = node.nextSibling;
   if (node.nodeType == 3 && !/\S/.test(node.nodeValue))
    element.removeChild(node);
   node = nextNode;
  }
  return element;
 },

 empty: function(element) {
  return $(element).innerHTML.match(/^\s*$/);
 },

 childOf: function(element, ancestor) {
  element = $(element), ancestor = $(ancestor);
  while (element = element.parentNode)
   if (element == ancestor) return true;
  return false;
 },

 scrollTo: function(element) {
  element = $(element);
  var x = element.x ? element.x : element.offsetLeft,
    y = element.y ? element.y : element.offsetTop;
  window.scrollTo(x, y);
  return element;
 },

 getStyle: function(element, style) {
  element = $(element);
  var value = element.style[style.camelize()];
  if (!value) {
   if (document.defaultView && document.defaultView.getComputedStyle) {
    var css = document.defaultView.getComputedStyle(element, null);
    value = css ? css.getPropertyValue(style) : null;
   } else if (element.currentStyle) {
    value = element.currentStyle[style.camelize()];
   }
  }

  if (window.opera && ['left', 'top', 'right', 'bottom'].include(style))
   if (Element.getStyle(element, 'position') == 'static') value = 'auto';

  return value == 'auto' ? null : value;
 },

 setStyle: function(element, style) {
  element = $(element);
  for (var name in style)
   element.style[name.camelize()] = style[name];
  return element;
 },

 getDimensions: function(element) {
  element = $(element);
  if (Element.getStyle(element, 'display') != 'none')
   return {width: element.offsetWidth, height: element.offsetHeight};

  // All *Width and *Height properties give 0 on elements with display none,
  // so enable the element temporarily
  var els = element.style;
  var originalVisibility = els.visibility;
  var originalPosition = els.position;
  els.visibility = 'hidden';
  els.position = 'absolute';
  els.display = '';
  var originalWidth = element.clientWidth;
  var originalHeight = element.clientHeight;
  els.display = 'none';
  els.position = originalPosition;
  els.visibility = originalVisibility;
  return {width: originalWidth, height: originalHeight};
 },

 makePositioned: function(element) {
  element = $(element);
  var pos = Element.getStyle(element, 'position');
  if (pos == 'static' || !pos) {
   element._madePositioned = true;
   element.style.position = 'relative';
   // Opera returns the offset relative to the positioning context, when an
   // element is position relative but top and left have not been defined
   if (window.opera) {
    element.style.top = 0;
    element.style.left = 0;
   }
  }
  return element;
 },

 undoPositioned: function(element) {
  element = $(element);
  if (element._madePositioned) {
   element._madePositioned = undefined;
   element.style.position =
    element.style.top =
    element.style.left =
    element.style.bottom =
    element.style.right = '';
  }
  return element;
 },

 makeClipping: function(element) {
  element = $(element);
  if (element._overflow) return;
  element._overflow = element.style.overflow || 'auto';
  if ((Element.getStyle(element, 'overflow') || 'visible') != 'hidden')
   element.style.overflow = 'hidden';
  return element;
 },

 undoClipping: function(element) {
  element = $(element);
  if (!element._overflow) return;
  element.style.overflow = element._overflow == 'auto' ? '' : element._overflow;
  element._overflow = null;
  return element;
 }
}

// IE is missing .innerHTML support for TABLE-related elements
if(document.all){
 Element.Methods.update = function(element, html) {
  element = $(element);
  var tagName = element.tagName.toUpperCase();
  if (['THEAD','TBODY','TR','TD'].indexOf(tagName) > -1) {
   var div = document.createElement('div');
   switch (tagName) {
    case 'THEAD':
    case 'TBODY':
     div.innerHTML = '<table><tbody>' + html.stripScripts() + '</tbody></table>';
     depth = 2;
     break;
    case 'TR':
     div.innerHTML = '<table><tbody><tr>' + html.stripScripts() + '</tr></tbody></table>';
     depth = 3;
     break;
    case 'TD':
     div.innerHTML = '<table><tbody><tr><td>' + html.stripScripts() + '</td></tr></tbody></table>';
     depth = 4;
   }
   $A(element.childNodes).each(function(node){
    element.removeChild(node)
   });
   depth.times(function(){ div = div.firstChild });

   $A(div.childNodes).each(
    function(node){ element.appendChild(node) });
  } else {
   element.innerHTML = html.stripScripts();
  }
  setTimeout(function() {html.evalScripts()}, 10);
  return element;
 }
}

Object.extend(Element, Element.Methods);

var _nativeExtensions = false;

if (!window.HTMLElement && /Konqueror|Safari|KHTML/.test(navigator.userAgent)) {
 /* Emulate HTMLElement, HTMLFormElement, HTMLInputElement, HTMLTextAreaElement,
   and HTMLSelectElement in Safari */
 ['', 'Form', 'Input', 'TextArea', 'Select'].each(function(tag) {
  var klass = window['HTML' + tag + 'Element'] = {};
  klass.prototype = document.createElement(tag ? tag.toLowerCase() : 'div').__proto__;
 });
}

Element.addMethods = function(methods) {
 Object.extend(Element.Methods, methods || {});

 function copy(methods, destination) {
  var cache = Element.extend.cache;
  for (var property in methods) {
   var value = methods[property];
   destination[property] = cache.findOrStore(value);
  }
 }

 if (typeof HTMLElement != 'undefined') {
  copy(Element.Methods, HTMLElement.prototype);
  copy(Form.Methods, HTMLFormElement.prototype);
  [HTMLInputElement, HTMLTextAreaElement, HTMLSelectElement].each(function(klass) {
   copy(Form.Element.Methods, klass.prototype);
  });
  _nativeExtensions = true;
 }
}

var Toggle = new Object();
Toggle.display = Element.toggle;

/*--------------------------------------------------------------------------*/

Abstract.Insertion = function(adjacency) {
 this.adjacency = adjacency;
}

Abstract.Insertion.prototype = {
 initialize: function(element, content) {
  this.element = $(element);
  this.content = content.stripScripts();

  if (this.adjacency && this.element.insertAdjacentHTML) {
   try {
    this.element.insertAdjacentHTML(this.adjacency, this.content);
   } catch (e) {
    var tagName = this.element.tagName.toLowerCase();
    if (tagName == 'tbody' || tagName == 'tr') {
     this.insertContent(this.contentFromAnonymousTable());
    } else {
     throw e;
    }
   }
  } else {
   this.range = this.element.ownerDocument.createRange();
   if (this.initializeRange) this.initializeRange();
   this.insertContent([this.range.createContextualFragment(this.content)]);
  }

  setTimeout(function() {content.evalScripts()}, 10);
 },

 contentFromAnonymousTable: function() {
  var div = document.createElement('div');
  div.innerHTML = '<table><tbody>' + this.content + '</tbody></table>';
  return $A(div.childNodes[0].childNodes[0].childNodes);
 }
}

var Insertion = new Object();

Insertion.Before = Class.create();
Insertion.Before.prototype = Object.extend(new Abstract.Insertion('beforeBegin'), {
 initializeRange: function() {
  this.range.setStartBefore(this.element);
 },

 insertContent: function(fragments) {
  fragments.each((function(fragment) {
   this.element.parentNode.insertBefore(fragment, this.element);
  }).bind(this));
 }
});

Insertion.Top = Class.create();
Insertion.Top.prototype = Object.extend(new Abstract.Insertion('afterBegin'), {
 initializeRange: function() {
  this.range.selectNodeContents(this.element);
  this.range.collapse(true);
 },

 insertContent: function(fragments) {
  fragments.reverse(false).each((function(fragment) {
   this.element.insertBefore(fragment, this.element.firstChild);
  }).bind(this));
 }
});

Insertion.Bottom = Class.create();
Insertion.Bottom.prototype = Object.extend(new Abstract.Insertion('beforeEnd'), {
 initializeRange: function() {
  this.range.selectNodeContents(this.element);
  this.range.collapse(this.element);
 },

 insertContent: function(fragments) {
  fragments.each((function(fragment) {
   this.element.appendChild(fragment);
  }).bind(this));
 }
});

Insertion.After = Class.create();
Insertion.After.prototype = Object.extend(new Abstract.Insertion('afterEnd'), {
 initializeRange: function() {
  this.range.setStartAfter(this.element);
 },

 insertContent: function(fragments) {
  fragments.each((function(fragment) {
   this.element.parentNode.insertBefore(fragment,
    this.element.nextSibling);
  }).bind(this));
 }
});

/*--------------------------------------------------------------------------*/

Element.ClassNames = Class.create();
Element.ClassNames.prototype = {
 initialize: function(element) {
  this.element = $(element);
 },

 _each: function(iterator) {
  this.element.className.split(/\s+/).select(function(name) {
   return name.length > 0;
  })._each(iterator);
 },

 set: function(className) {
  this.element.className = className;
 },

 add: function(classNameToAdd) {
  if (this.include(classNameToAdd)) return;
  this.set(this.toArray().concat(classNameToAdd).join(' '));
 },

 remove: function(classNameToRemove) {
  if (!this.include(classNameToRemove)) return;
  this.set(this.select(function(className) {
   return className != classNameToRemove;
  }).join(' '));
 },

 toString: function() {
  return this.toArray().join(' ');
 }
}

Object.extend(Element.ClassNames.prototype, Enumerable);
var Selector = Class.create();
Selector.prototype = {
 initialize: function(expression) {
  this.params = {classNames: []};
  this.expression = expression.toString().strip();
  this.parseExpression();
  this.compileMatcher();
 },

 parseExpression: function() {
  function abort(message) { throw 'Parse error in selector: ' + message; }

  if (this.expression == '') abort('empty expression');

  var params = this.params, expr = this.expression, match, modifier, clause, rest;
  while (match = expr.match(/^(.*)\[([a-z0-9_:-]+?)(?:([~\|!]?=)(?:"([^"]*)"|([^\]\s]*)))?\]$/i)) {
   params.attributes = params.attributes || [];
   params.attributes.push({name: match[2], operator: match[3], value: match[4] || match[5] || ''});
   expr = match[1];
  }

  if (expr == '*') return this.params.wildcard = true;

  while (match = expr.match(/^([^a-z0-9_-])?([a-z0-9_-]+)(.*)/i)) {
   modifier = match[1], clause = match[2], rest = match[3];
   switch (modifier) {
    case '#':    params.id = clause; break;
    case '.':    params.classNames.push(clause); break;
    case '':
    case undefined: params.tagName = clause.toUpperCase(); break;
    default:    abort(expr.inspect());
   }
   expr = rest;
  }

  if (expr.length > 0) abort(expr.inspect());
 },

 buildMatchExpression: function() {
  var params = this.params, conditions = [], clause;

  if (params.wildcard)
   conditions.push('true');
  if (clause = params.id)
   conditions.push('element.id == ' + clause.inspect());
  if (clause = params.tagName)
   conditions.push('element.tagName.toUpperCase() == ' + clause.inspect());
  if ((clause = params.classNames).length > 0)
   for (var i = 0; i < clause.length; i++)
    conditions.push('Element.hasClassName(element, ' + clause[i].inspect() + ')');
  if (clause = params.attributes) {
   clause.each(function(attribute) {
    var value = 'element.getAttribute(' + attribute.name.inspect() + ')';
    var splitValueBy = function(delimiter) {
     return value + ' && ' + value + '.split(' + delimiter.inspect() + ')';
    }

    switch (attribute.operator) {
     case '=':    conditions.push(value + ' == ' + attribute.value.inspect()); break;
     case '~=':   conditions.push(splitValueBy(' ') + '.include(' + attribute.value.inspect() + ')'); break;
     case '|=':   conditions.push(
              splitValueBy('-') + '.first().toUpperCase() == ' + attribute.value.toUpperCase().inspect()
             ); break;
     case '!=':   conditions.push(value + ' != ' + attribute.value.inspect()); break;
     case '':
     case undefined: conditions.push(value + ' != null'); break;
     default:    throw 'Unknown operator ' + attribute.operator + ' in selector';
    }
   });
  }

  return conditions.join(' && ');
 },

 compileMatcher: function() {
  this.match = new Function('element', 'if (!element.tagName) return false; \
   return ' + this.buildMatchExpression());
 },

 findElements: function(scope) {
  var element;

  if (element = $(this.params.id))
   if (this.match(element))
    if (!scope || Element.childOf(element, scope))
     return [element];

  scope = (scope || document).getElementsByTagName(this.params.tagName || '*');

  var results = [];
  for (var i = 0; i < scope.length; i++)
   if (this.match(element = scope[i]))
    results.push(Element.extend(element));

  return results;
 },

 toString: function() {
  return this.expression;
 }
}

Object.extend(Selector, {
 matchElements: function(elements, expression) {
  var selector = new Selector(expression);
  return elements.select(selector.match.bind(selector));
 },

 findElement: function(elements, expression, index) {
  if (typeof expression == 'number') index = expression, expression = false;
  return Selector.matchElements(elements, expression || '*')[index || 0];
 },

 findChildElements: function(element, expressions) {
  return expressions.map(function(expression) {
   return expression.strip().split(/\s+/).inject([null], function(results, expr) {
    var selector = new Selector(expr);
    return results.inject([], function(elements, result) {
     return elements.concat(selector.findElements(result || element));
    });
   });
  }).flatten();
 }
});

function $$() {
 return Selector.findChildElements(document, $A(arguments));
}
var Form = {
 reset: function(form) {
  $(form).reset();
  return form;
 }
};

Form.Methods = {
 serialize: function(form) {
  var elements = Form.getElements($(form));
  var queryComponents = new Array();

  for (var i = 0; i < elements.length; i++) {
   var queryComponent = Form.Element.serialize(elements[i]);
   if (queryComponent)
    queryComponents.push(queryComponent);
  }

  return queryComponents.join('&');
 },

 getElements: function(form) {
  form = $(form);
  var elements = new Array();

  for (var tagName in Form.Element.Serializers) {
   var tagElements = form.getElementsByTagName(tagName);
   for (var j = 0; j < tagElements.length; j++)
    elements.push(tagElements[j]);
  }
  return elements;
 },

 getInputs: function(form, typeName, name) {
  form = $(form);
  var inputs = form.getElementsByTagName('input');

  if (!typeName && !name)
   return inputs;

  var matchingInputs = new Array();
  for (var i = 0; i < inputs.length; i++) {
   var input = inputs[i];
   if ((typeName && input.type != typeName) ||
     (name && input.name != name))
    continue;
   matchingInputs.push(input);
  }

  return matchingInputs;
 },

 disable: function(form) {
  form = $(form);
  var elements = Form.getElements(form);
  for (var i = 0; i < elements.length; i++) {
   var element = elements[i];
   element.blur();
   element.disabled = 'true';
  }
  return form;
 },

 enable: function(form) {
  form = $(form);
  var elements = Form.getElements(form);
  for (var i = 0; i < elements.length; i++) {
   var element = elements[i];
   element.disabled = '';
  }
  return form;
 },

 findFirstElement: function(form) {
  return Form.getElements(form).find(function(element) {
   return element.type != 'hidden' && !element.disabled &&
    ['input', 'select', 'textarea'].include(element.tagName.toLowerCase());
  });
 },

 focusFirstElement: function(form) {
  form = $(form);
  Field.activate(Form.findFirstElement(form));
  return form;
 }
}

Object.extend(Form, Form.Methods);

/*--------------------------------------------------------------------------*/

Form.Element = {
 focus: function(element) {
  $(element).focus();
  return element;
 },

 select: function(element) {
  $(element).select();
  return element;
 }
}

Form.Element.Methods = {
 serialize: function(element) {
  element = $(element);
  var method = element.tagName.toLowerCase();
  var parameter = Form.Element.Serializers[method](element);

  if (parameter) {
   var key = encodeURIComponent(parameter[0]);
   if (key.length == 0) return;

   if (parameter[1].constructor != Array)
    parameter[1] = [parameter[1]];

   return parameter[1].map(function(value) {
    return key + '=' + encodeURIComponent(value);
   }).join('&');
  }
 },

 getValue: function(element) {
  element = $(element);
  var method = element.tagName.toLowerCase();
  var parameter = Form.Element.Serializers[method](element);

  if (parameter)
   return parameter[1];
 },

 clear: function(element) {
  $(element).value = '';
  return element;
 },

 present: function(element) {
  return $(element).value != '';
 },

 activate: function(element) {
  element = $(element);
  element.focus();
  if (element.select)
   element.select();
  return element;
 },

 disable: function(element) {
  element = $(element);
  element.disabled = '';
  return element;
 },

 enable: function(element) {
  element = $(element);
  element.blur();
  element.disabled = 'true';
  return element;
 }
}

Object.extend(Form.Element, Form.Element.Methods);
var Field = Form.Element;

/*--------------------------------------------------------------------------*/

Form.Element.Serializers = {
 input: function(element) {
  switch (element.type.toLowerCase()) {
   case 'checkbox':
   case 'radio':
    return Form.Element.Serializers.inputSelector(element);
   default:
    return Form.Element.Serializers.textarea(element);
  }
  return false;
 },

 inputSelector: function(element) {
  if (element.checked)
   return [element.name, element.value];
 },

 textarea: function(element) {
  return [element.name, element.value];
 },

 select: function(element) {
  return Form.Element.Serializers[element.type == 'select-one' ?
   'selectOne' : 'selectMany'](element);
 },

 selectOne: function(element) {
  var value = '', opt, index = element.selectedIndex;
  if (index >= 0) {
   opt = element.options[index];
   value = opt.value || opt.text;
  }
  return [element.name, value];
 },

 selectMany: function(element) {
  var value = [];
  for (var i = 0; i < element.length; i++) {
   var opt = element.options[i];
   if (opt.selected)
    value.push(opt.value || opt.text);
  }
  return [element.name, value];
 }
}

/*--------------------------------------------------------------------------*/

var $F = Form.Element.getValue;

/*--------------------------------------------------------------------------*/

Abstract.TimedObserver = function() {}
Abstract.TimedObserver.prototype = {
 initialize: function(element, frequency, callback) {
  this.frequency = frequency;
  this.element  = $(element);
  this.callback = callback;

  this.lastValue = this.getValue();
  this.registerCallback();
 },

 registerCallback: function() {
  setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
 },

 onTimerEvent: function() {
  var value = this.getValue();
  if (this.lastValue != value) {
   this.callback(this.element, value);
   this.lastValue = value;
  }
 }
}

Form.Element.Observer = Class.create();
Form.Element.Observer.prototype = Object.extend(new Abstract.TimedObserver(), {
 getValue: function() {
  return Form.Element.getValue(this.element);
 }
});

Form.Observer = Class.create();
Form.Observer.prototype = Object.extend(new Abstract.TimedObserver(), {
 getValue: function() {
  return Form.serialize(this.element);
 }
});

/*--------------------------------------------------------------------------*/

Abstract.EventObserver = function() {}
Abstract.EventObserver.prototype = {
 initialize: function(element, callback) {
  this.element = $(element);
  this.callback = callback;

  this.lastValue = this.getValue();
  if (this.element.tagName.toLowerCase() == 'form')
   this.registerFormCallbacks();
  else
   this.registerCallback(this.element);
 },

 onElementEvent: function() {
  var value = this.getValue();
  if (this.lastValue != value) {
   this.callback(this.element, value);
   this.lastValue = value;
  }
 },

 registerFormCallbacks: function() {
  var elements = Form.getElements(this.element);
  for (var i = 0; i < elements.length; i++)
   this.registerCallback(elements[i]);
 },

 registerCallback: function(element) {
  if (element.type) {
   switch (element.type.toLowerCase()) {
    case 'checkbox':
    case 'radio':
     Event.observe(element, 'click', this.onElementEvent.bind(this));
     break;
    default:
     Event.observe(element, 'change', this.onElementEvent.bind(this));
     break;
   }
  }
 }
}

Form.Element.EventObserver = Class.create();
Form.Element.EventObserver.prototype = Object.extend(new Abstract.EventObserver(), {
 getValue: function() {
  return Form.Element.getValue(this.element);
 }
});

Form.EventObserver = Class.create();
Form.EventObserver.prototype = Object.extend(new Abstract.EventObserver(), {
 getValue: function() {
  return Form.serialize(this.element);
 }
});
if (!window.Event) {
 var Event = new Object();
}

Object.extend(Event, {
 KEY_BACKSPACE: 8,
 KEY_TAB:    9,
 KEY_RETURN:  13,
 KEY_ESC:   27,
 KEY_LEFT:   37,
 KEY_UP:    38,
 KEY_RIGHT:  39,
 KEY_DOWN:   40,
 KEY_DELETE:  46,
 KEY_HOME:   36,
 KEY_END:   35,
 KEY_PAGEUP:  33,
 KEY_PAGEDOWN: 34,

 element: function(event) {
  return event.target || event.srcElement;
 },

 isLeftClick: function(event) {
  return (((event.which) && (event.which == 1)) ||
      ((event.button) && (event.button == 1)));
 },

 pointerX: function(event) {
  return event.pageX || (event.clientX +
   (document.documentElement.scrollLeft || document.body.scrollLeft));
 },

 pointerY: function(event) {
  return event.pageY || (event.clientY +
   (document.documentElement.scrollTop || document.body.scrollTop));
 },

 stop: function(event) {
  if (event.preventDefault) {
   event.preventDefault();
   event.stopPropagation();
  } else {
   event.returnValue = false;
   event.cancelBubble = true;
  }
 },

 // find the first node with the given tagName, starting from the
 // node the event was triggered on; traverses the DOM upwards
 findElement: function(event, tagName) {
  var element = Event.element(event);
  while (element.parentNode && (!element.tagName ||
    (element.tagName.toUpperCase() != tagName.toUpperCase())))
   element = element.parentNode;
  return element;
 },

 observers: false,

 _observeAndCache: function(element, name, observer, useCapture) {
  if (!this.observers) this.observers = [];
  if (element.addEventListener) {
   this.observers.push([element, name, observer, useCapture]);
   element.addEventListener(name, observer, useCapture);
  } else if (element.attachEvent) {
   this.observers.push([element, name, observer, useCapture]);
   element.attachEvent('on' + name, observer);
  }
 },

 unloadCache: function() {
  if (!Event.observers) return;
  for (var i = 0; i < Event.observers.length; i++) {
   Event.stopObserving.apply(this, Event.observers[i]);
   Event.observers[i][0] = null;
  }
  Event.observers = false;
 },

 observe: function(element, name, observer, useCapture) {
  element = $(element);
  useCapture = useCapture || false;

  if (name == 'keypress' &&
    (navigator.appVersion.match(/Konqueror|Safari|KHTML/)
    || element.attachEvent))
   name = 'keydown';

  Event._observeAndCache(element, name, observer, useCapture);
 },

 stopObserving: function(element, name, observer, useCapture) {
  element = $(element);
  useCapture = useCapture || false;

  if (name == 'keypress' &&
    (navigator.appVersion.match(/Konqueror|Safari|KHTML/)
    || element.detachEvent))
   name = 'keydown';

  if (element.removeEventListener) {
   element.removeEventListener(name, observer, useCapture);
  } else if (element.detachEvent) {
   try {
    element.detachEvent('on' + name, observer);
   } catch (e) {}
  }
 }
});

/* prevent memory leaks in IE */
if (navigator.appVersion.match(/\bMSIE\b/))
 Event.observe(window, 'unload', Event.unloadCache, false);
var Position = {
 // set to true if needed, warning: firefox performance problems
 // NOT neeeded for page scrolling, only if draggable contained in
 // scrollable elements
 includeScrollOffsets: false,

 // must be called before calling withinIncludingScrolloffset, every time the
 // page is scrolled
 prepare: function() {
  this.deltaX = window.pageXOffset
        || document.documentElement.scrollLeft
        || document.body.scrollLeft
        || 0;
  this.deltaY = window.pageYOffset
        || document.documentElement.scrollTop
        || document.body.scrollTop
        || 0;
 },

 realOffset: function(element) {
  var valueT = 0, valueL = 0;
  do {
   valueT += element.scrollTop || 0;
   valueL += element.scrollLeft || 0;
   element = element.parentNode;
  } while (element);
  return [valueL, valueT];
 },

 cumulativeOffset: function(element) {
  var valueT = 0, valueL = 0;
  do {
   valueT += element.offsetTop || 0;
   valueL += element.offsetLeft || 0;
   element = element.offsetParent;
  } while (element);
  return [valueL, valueT];
 },

 positionedOffset: function(element) {
  var valueT = 0, valueL = 0;
  do {
   valueT += element.offsetTop || 0;
   valueL += element.offsetLeft || 0;
   element = element.offsetParent;
   if (element) {
    p = Element.getStyle(element, 'position');
    if (p == 'relative' || p == 'absolute') break;
   }
  } while (element);
  return [valueL, valueT];
 },

 offsetParent: function(element) {
  if (element.offsetParent) return element.offsetParent;
  if (element == document.body) return element;

  while ((element = element.parentNode) && element != document.body)
   if (Element.getStyle(element, 'position') != 'static')
    return element;

  return document.body;
 },

 // caches x/y coordinate pair to use with overlap
 within: function(element, x, y) {
  if (this.includeScrollOffsets)
   return this.withinIncludingScrolloffsets(element, x, y);
  this.xcomp = x;
  this.ycomp = y;
  this.offset = this.cumulativeOffset(element);

  return (y >= this.offset[1] &&
      y < this.offset[1] + element.offsetHeight &&
      x >= this.offset[0] &&
      x < this.offset[0] + element.offsetWidth);
 },

 withinIncludingScrolloffsets: function(element, x, y) {
  var offsetcache = this.realOffset(element);

  this.xcomp = x + offsetcache[0] - this.deltaX;
  this.ycomp = y + offsetcache[1] - this.deltaY;
  this.offset = this.cumulativeOffset(element);

  return (this.ycomp >= this.offset[1] &&
      this.ycomp < this.offset[1] + element.offsetHeight &&
      this.xcomp >= this.offset[0] &&
      this.xcomp < this.offset[0] + element.offsetWidth);
 },

 // within must be called directly before
 overlap: function(mode, element) {
  if (!mode) return 0;
  if (mode == 'vertical')
   return ((this.offset[1] + element.offsetHeight) - this.ycomp) /
    element.offsetHeight;
  if (mode == 'horizontal')
   return ((this.offset[0] + element.offsetWidth) - this.xcomp) /
    element.offsetWidth;
 },

 page: function(forElement) {
  var valueT = 0, valueL = 0;

  var element = forElement;
  do {
   valueT += element.offsetTop || 0;
   valueL += element.offsetLeft || 0;

   // Safari fix
   if (element.offsetParent==document.body)
    if (Element.getStyle(element,'position')=='absolute') break;

  } while (element = element.offsetParent);

  element = forElement;
  do {
   if (!window.opera || element.tagName=='BODY') {
    valueT -= element.scrollTop || 0;
    valueL -= element.scrollLeft || 0;
   }
  } while (element = element.parentNode);

  return [valueL, valueT];
 },

 clone: function(source, target) {
  var options = Object.extend({
   setLeft:  true,
   setTop:   true,
   setWidth:  true,
   setHeight: true,
   offsetTop: 0,
   offsetLeft: 0
  }, arguments[2] || {})

  // find page position of source
  source = $(source);
  var p = Position.page(source);

  // find coordinate system to use
  target = $(target);
  var delta = [0, 0];
  var parent = null;
  // delta [0,0] will do fine with position: fixed elements,
  // position:absolute needs offsetParent deltas
  if (Element.getStyle(target,'position') == 'absolute') {
   parent = Position.offsetParent(target);
   delta = Position.page(parent);
  }

  // correct by body offsets (fixes Safari)
  if (parent == document.body) {
   delta[0] -= document.body.offsetLeft;
   delta[1] -= document.body.offsetTop;
  }

  // set position
  if(options.setLeft)  target.style.left = (p[0] - delta[0] + options.offsetLeft) + 'px';
  if(options.setTop)  target.style.top  = (p[1] - delta[1] + options.offsetTop) + 'px';
  if(options.setWidth) target.style.width = source.offsetWidth + 'px';
  if(options.setHeight) target.style.height = source.offsetHeight + 'px';
 },

 absolutize: function(element) {
  element = $(element);
  if (element.style.position == 'absolute') return;
  Position.prepare();

  var offsets = Position.positionedOffset(element);
  var top   = offsets[1];
  var left  = offsets[0];
  var width  = element.clientWidth;
  var height = element.clientHeight;

  element._originalLeft  = left - parseFloat(element.style.left || 0);
  element._originalTop  = top - parseFloat(element.style.top || 0);
  element._originalWidth = element.style.width;
  element._originalHeight = element.style.height;

  element.style.position = 'absolute';
  element.style.top  = top + 'px';;
  element.style.left  = left + 'px';;
  element.style.width = width + 'px';;
  element.style.height = height + 'px';;
 },

 relativize: function(element) {
  element = $(element);
  if (element.style.position == 'relative') return;
  Position.prepare();

  element.style.position = 'relative';
  var top = parseFloat(element.style.top || 0) - (element._originalTop || 0);
  var left = parseFloat(element.style.left || 0) - (element._originalLeft || 0);

  element.style.top  = top + 'px';
  element.style.left  = left + 'px';
  element.style.height = element._originalHeight;
  element.style.width = element._originalWidth;
 }
}

// Safari returns margins on body which is incorrect if the child is absolutely
// positioned. For performance reasons, redefine Position.cumulativeOffset for
// KHTML/WebKit only.
if (/Konqueror|Safari|KHTML/.test(navigator.userAgent)) {
 Position.cumulativeOffset = function(element) {
  var valueT = 0, valueL = 0;
  do {
   valueT += element.offsetTop || 0;
   valueL += element.offsetLeft || 0;
   if (element.offsetParent == document.body)
    if (Element.getStyle(element, 'position') == 'absolute') break;

   element = element.offsetParent;
  } while (element);

  return [valueL, valueT];
 }
}

Element.addMethods();