/*  Prototype JavaScript framework, version 1.3.1
 *  (c) 2005 Sam Stephenson <sam@conio.net>
 *
 *  THIS FILE IS AUTOMATICALLY GENERATED. When sending patches, please diff
 *  against the source tree, available from the Prototype darcs repository. 
 *
 *  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: '1.3.1',
    emptyFunction: function() {}
}

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

var Abstract = new Object();

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

Object.prototype.extend = function(object) {
    return Object.extend.apply(this, [this, object]);
}

Function.prototype.bind = function(object) {
    var __method = this;
    return function() {
        __method.apply(object, arguments);
    }
}

Function.prototype.bindAsEventListener = function(object) {
    var __method = this;
    return function(event) {
        __method.call(object, event || window.event);
    }
}

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

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

    onTimerEvent: function() {
        if (!this.currentlyExecuting) {
            try { 
                this.currentlyExecuting = true;
                this.callback(); 
            } finally { 
                this.currentlyExecuting = false;
            }
        }
    }
}

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

function $() {
    var elements = new Array();

    for (var i = 0; i < arguments.length; i++) {
        var element = arguments[i];
        if (typeof element == 'string')
            element = document.getElementById(element);

        if (arguments.length == 1) 
            return element;

        elements.push(element);
    }

    return elements;
}

if (!Array.prototype.push) {
    Array.prototype.push = function() {
		var startLength = this.length;
		for (var i = 0; i < arguments.length; i++) {
            this[startLength + i] = arguments[i];
		}
  	    return this.length;
    }
}

Array.prototype.pushArray = function() {
    for (var i = 0; i < arguments.length; i++) {
        for (var j = 0; j < arguments[ i ].length; j++) {
            this.push(arguments[ i ][ j ]);
        }
    }
}

if (!Function.prototype.apply) {
    // Based on code from http://www.youngpup.net/
    Function.prototype.apply = function(object, parameters) {
        var parameterStrings = new Array();
        if (!object)     object = window;
        if (!parameters) parameters = new Array();
        
        for (var i = 0; i < parameters.length; i++)
            parameterStrings[i] = 'parameters[' + i + ']';
        
        object.__apply__ = this;
        var result = eval('object.__apply__(' + 
            parameterStrings.join(', ') + ')');
        object.__apply__ = null;
        
        return result;
    }
}

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

    encode: function() {
        return this.replace(/&/img, encodeURIComponent('&')).replace(/=/img, encodeURIComponent('='));
    },
    
    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].nodeValue;
    },

    htmlEntities: function() {
        return this.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;').replace(/'/g, '&apos;');
    },
    
    trim: function() {
        return this.replace(/\s/g, '');
    }
});

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

Ajax.Base = function() {};
Ajax.Base.prototype = {
    setOptions: function(options) {
        this.options = {
            method:       'post',
            asynchronous: true,
            parameters:   ''
        }.extend(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.ErrorFragment = '(?:<xmlError.*?>)((\n|.)*?)(?:<\/xmlError>)';
Ajax.Request.Events = 
    ['Uninitialized', 'Loading', 'Loaded', 'Interactive', 'Complete'];

Ajax.Request.prototype = (new Ajax.Base()).extend({
    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 += '&_=';

        try {
            if (this.options.method == 'get')
                url += '?' + parameters;

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

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

            this.setRequestHeaders();

            var body = this.options.postBody ? this.options.postBody : parameters;
            this.transport.send(this.options.method == 'post' ? body : null);
        
            // check return
            if (!this.options.asynchronous && !this.updateContent && this.responseIsSuccess() && this.transport.responseText) {
                var error = this.checkError();
                if (error != false) {
                    (this.options.onError || Prototype.emptyFunction)(error);
                    (this.options.onFailure || Prototype.emptyFunction)(this.transport);
                } else {
                    (this.options.onSuccess || Prototype.emptyFunction)(this.transport);
                }
            }
        } catch (e) {
        }
    },
    
    checkError: function (error) {
        var match = new RegExp(Ajax.Request.ErrorFragment, 'img');
        var error = this.transport.responseText.match(match);

        // error?
        if (error) {
            // get the html of the error
            return error.toString().replace(match, '$1');
        } else {
            return false;
        }
    },

    setRequestHeaders: function() {
        var requestHeaders = 
            ['X-Requested-With', 'XMLHttpRequest',
              'X-Prototype-Version', Prototype.Version];

        if (this.options.method == 'post') {
            requestHeaders.push('Content-type', 'application/x-www-form-urlencoded');

            /* 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);
    },

    respondToReadyState: function(readyState) {
        var event = Ajax.Request.Events[readyState];

        if (event == 'Complete') {
            // does it match the error?
            var sErrorMessage = this.checkError();
        
            // error?
            if (sErrorMessage != false) {
                (this.options['onError'] || Prototype.emptyFunction)(sErrorMessage);
            } else {
                // call function
                (this.options['on' + this.transport.status] || this.options['on' + (this.responseIsSuccess() ? 'Success' : 'Failure')] || Prototype.emptyFunction)(this.transport);
            }
        }

        (this.options['on' + event] || Prototype.emptyFunction)(this.transport);

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

Ajax.Updater = Class.create();
Ajax.Updater.ScriptFragment = '(?:<script.*?>)((\n|.)*?)(?:<\/script>)';
Ajax.Updater.RequestFragment = '(?:<xmlRequest.*?>)((\n|.)*?)(?:<\/xmlRequest>)';

Ajax.Updater.prototype.extend(Ajax.Request.prototype).extend({
    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() {
            this.updateContent();
            onComplete(this.transport);
        }).bind(this);

        this.request(url);
    },

    updateContent: function() {
        // check error
        if (this.checkError() != false) {
            return;
        }

        // no error
        var receiver = this.responseIsSuccess() ? this.containers.success : this.containers.failure;

        var match    = new RegExp(Ajax.Updater.ScriptFragment, 'img');
        var request  = new RegExp(Ajax.Updater.RequestFragment, 'img');
        var response = this.transport.responseText.match(request);
        if (response) response = response.toString().replace(match, '');
        if (response) response = response.toString().replace(request, '$1');
        var scripts  = this.transport.responseText.match(match);

        if (receiver) {
            if (this.options.insertion) {
                new this.options.insertion(receiver, response);
            } else {
                receiver.innerHTML = response;
            }
        }

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

        if (this.options.evalScripts && scripts) {
            match = new RegExp(Ajax.Updater.ScriptFragment, 'im');
            setTimeout((function() {
                for (var i = 0; i < scripts.length; i++) {
                    try {
                        eval(scripts[i].match(match)[1]);
                    } catch (e) {
                        alert("Parse error: " + e + "\n\n" + scripts[ i ]);
                    }
                }
            }).bind(this), 10);
        }
    }
});

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

        this.frequency = (this.options.frequency || 2);
        this.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.onComplete = undefined;
        clearTimeout(this.timer);
        (this.onComplete || Ajax.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);
    }
});

document.getElementsByClassName = function(className) {
    var children = document.getElementsByTagName('*') || document.all;
    var elements = new Array();
    
    for (var i = 0; i < children.length; i++) {
        var child = children[i];
        var classNames = child.className.split(' ');
        for (var j = 0; j < classNames.length; j++) {
            if (classNames[j] == className) {
                elements.push(child);
                break;
            }
        }
    }
    
    return elements;
}

var _DOMSerializer = {
    serializeNode: function(oNode) {
        // need node type
        if (typeof(oNode) == 'undefined' || typeof(oNode.nodeType) == 'undefined') {
            return '';
        }
        
        // what kind of node?
        switch (oNode.nodeType) {
            case 1: // element
                // serialize attributes
                var sAttributes = _DOMSerializer.serializeAttributeNodes(oNode);
                
                // return
                if (oNode.childNodes.length > 0) {
                    return '<' + oNode.nodeName + sAttributes + '>' + _DOMSerializer.serializeChildNodes(oNode) + '</' + oNode.nodeName + '>';
                } else {
                    return '<' + oNode.nodeName + sAttributes + '/>';
                }
                break;
            
            case 2: // attribute
                // just return
                return oNode.name.match(/^_moz/) ? null : oNode.name + '="' + oNode.value.htmlEntities() + '"';
            
            case 3: // text node
                // just return
                return oNode.data.htmlEntities();
            
            default:
                alert("Unhandled node type: " + oNode.nodeType);
                break;
        }
    },
    
    debugNode: function(oNode) {
        var s = '';
        for (var obj in oNode) {
            if (typeof(oNode[ obj ]) != 'function') {
                s += obj + " => " + oNode[ obj ] + ", ";
            } else {
                s += obj + " => function, ";
            }
        }
        alert(s);
    },
    
    serializeChildNodes: function(oNode) {
        // need child nodes
        if (typeof(oNode) == 'undefined' || typeof(oNode.childNodes) == 'undefined') {
            return '';
        }
        
        // serialize child nodes
        return _DOMSerializer.serializeNodeList(oNode.childNodes).join('');
    },
    
    serializeAttributeNodes: function(oNode) {
        // need attributes
        if (typeof(oNode) == 'undefined' || typeof(oNode.attributes) == 'undefined') {
            return '';
        }
        
        // serialize attributes
        return ((oNode.attributes.length > 0) ? ' ' : '') + _DOMSerializer.serializeNodeList(oNode.attributes).join(' ');
    },
    
    serializeNodeList: function(aNodes) {
        // array
        var aSerialized = new Array(), oNode = null;
        
        // serialize child nodes
        for (var iNode = 0; iNode < aNodes.length; iNode++) {
            // only add nodes that aren't null
            oNode = _DOMSerializer.serializeNode(aNodes[ iNode ]);
            if (oNode != null) {
                aSerialized.push(_DOMSerializer.serializeNode(aNodes[ iNode ]));
            }
        }
        
        // return array
        return aSerialized;
    }
};

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

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

Object.extend(Element, {
    toggle: function() {
        for (var i = 0; i < arguments.length; i++) {
            var element = $(arguments[i]);
            element.style.display = 
                (element.style.display == 'none' ? '' : 'none');
        }
    },

    hide: function() {
        for (var i = 0; i < arguments.length; i++) {
            var element = $(arguments[i]);
            if (element) {
                element.style.display = 'none';
            }
        }
    },

    show: function() {
        for (var i = 0; i < arguments.length; i++) {
            var element = $(arguments[i]);
            element.style.display = '';
        }
    },

    removeChildren: function(element) {
        element = $(element);
        if (element && element.childNodes && element.childNodes.length) {
            for (var iChild = element.childNodes.length; iChild; --iChild) {
                element.removeChild(element.childNodes[iChild - 1]);
            }
        }
    },

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

    hasClassName: function(element, className) {
        element = $(element);
        if (!element) {
            return;
        }
        var a = element.className.split(' ');
        for (var i = 0; i < a.length; i++) {
            if (a[i] == className) {
                return true;
            }
        }
        return false;
    },

    addClassName: function(className) {
        for (var i = 1; i < arguments.length; i++) {
            var element = $(arguments[i]);
            if (!element) {
                continue;
            }
            if (typeof(element.length) == 'number' && typeof(element.item) == 'function') {
                for (var j = 0; j < element.length; j++) {
                    Element.addClassName(className, element[ j ]);
                }
            } else {
                Element.removeClassName(className, element);
                element.className += ' ' + className;
            }
        }
    },

    removeClassName: function(className) {
        for (var i = 1; i < arguments.length; i++) {
            var element = $(arguments[ i ]);
            if (!element) {
                continue;
            }
            if (typeof(element.length) == 'number' && typeof(element.item) == 'function') {
                for (var j = 0; j < element.length; j++) {
                    Element.removeClassName(className, element[ j ]);
                }
            } else {
                var newClassName = '';
                var a = element.className.split(' ');
                for (var i = 0; i < a.length; i++) {
                    if (a[i] != className) {
                        if (i > 0) {
                            newClassName += ' ';
                        }
                        newClassName += a[i];
                    }
                }
                element.className = newClassName;
            }
        }
    },
    
    // removes whitespace-only text node children
    cleanWhitespace: function(element) {
        var element = $(element);
        for (var i = 0; i < element.childNodes.length; i++) {
            var node = element.childNodes[i];
            if (node.nodeType == 3 && !/\S/.test(node.nodeValue)) 
                Element.remove(node);
        }
    }
});

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;
        
        if (this.adjacency && this.element.insertAdjacentHTML) {
            this.element.insertAdjacentHTML(this.adjacency, this.content);
        } else {
            this.range = this.element.ownerDocument.createRange();
            if (this.initializeRange) this.initializeRange();
            this.fragment = this.range.createContextualFragment(this.content);
            this.insertContent();
        }
    }
}

var Insertion = new Object();

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

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

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

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

var Field = {
    clear: function() {
        for (var i = 0; i < arguments.length; i++)
            $(arguments[i]).value = '';
    },

    focus: function(element) {
        $(element).focus();
    },
    
    present: function() {
        for (var i = 0; i < arguments.length; i++)
            if ($(arguments[i]).value == '') return false;
        return true;
    },
    
    select: function(element) {
        $(element).select();
    },
      
    activate: function(element) {
        $(element).focus();
        $(element).select();
    }
}

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

var Form = {
    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) {
        var form = $(form);
        if (!form) {
            return;
        }
        var elements = new Array();

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

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

    focusFirstElement: function(form) {
        var form = $(form);
        var elements = Form.getElements(form);
        for (var i = 0; i < elements.length; i++) {
            var element = elements[i];
            if (element.type != 'hidden' && !element.disabled) {
                Field.activate(element);
                break;
            }
        }
    },

    reset: function(form) {
        $(form).reset();
    }
}

Form.Element = {
    serialize: function(element) {
        var element = $(element);
        var method = element.tagName.toLowerCase();
        var parameter = Form.Element.Serializers[method](element);
        
        if (parameter) {
            return parameter[0].encode() + '=' + (parameter[1] ? parameter[1].encode() : ''.encode());
        }
    },
    
    getValue: function(element) {
        var element = $(element);
        var method = element.tagName.toLowerCase();
        var parameter = Form.Element.Serializers[method](element);
        
        if (parameter) {
            return parameter[1];
        }
    }
}

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

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

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

    select: function(element) {
        var value = '';
        if (element.type == 'select-one') {
            var index = element.selectedIndex;
            if (index >= 0)
                value = element.options[index].value || element.options[index].text;
        } else {
            value = new Array();
            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 = (new Abstract.TimedObserver()).extend({
    getValue: function() {
        return Form.Element.getValue(this.element);
    }
});

Form.Observer = Class.create();
Form.Observer.prototype = (new Abstract.TimedObserver()).extend({
    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':
                    element.target = this;
                    element.prev_onclick = element.onclick || Prototype.emptyFunction;
                    element.onclick = function() {
                        this.prev_onclick(); 
                        this.target.onElementEvent();
                    }
                    break;
                case 'password':
                case 'text':
                case 'textarea':
                case 'select-one':
                case 'select-multiple':
                    element.target = this;
                    element.prev_onchange = element.onchange || Prototype.emptyFunction;
                    element.onchange = function() {
                        this.prev_onchange(); 
                        this.target.onElementEvent();
                    }
                    break;
            }
        }    
    }
}

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

Form.EventObserver = Class.create();
Form.EventObserver.prototype = (new Abstract.EventObserver()).extend({
    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,

    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;
        }
    },

    // 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) {
        var element = $(element);
        useCapture = useCapture || false;
        
        if (name == 'keypress' &&
                ((navigator.appVersion.indexOf('AppleWebKit') > 0) 
                || element.attachEvent))
            name = 'keydown';
        
        this._observeAndCache(element, name, observer, useCapture);
    },

    stopObserving: function(element, name, observer, useCapture) {
        var element = $(element);
        useCapture = useCapture || false;
        
        if (name == 'keypress' &&
                ((navigator.appVersion.indexOf('AppleWebKit') > 0) 
                || element.detachEvent))
            name = 'keydown';
        
        if (element.removeEventListener) {
            element.removeEventListener(name, observer, useCapture);
        } else if (element.detachEvent) {
            element.detachEvent('on' + name, observer);
        }
    }
});

/* prevent memory leaks in IE */
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];
    },

    // 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;
    },

    clone: function(source, target) {
        source = $(source);
        target = $(target);
        target.style.position = 'absolute';
        var offsets = this.cumulativeOffset(source);
        target.style.top    = offsets[1] + 'px';
        target.style.left   = offsets[0] + 'px';
        target.style.width  = source.offsetWidth + 'px';
        target.style.height = source.offsetHeight + 'px';
    }
}