/**
                             * Provides Tab instances for use with TabView
                             * @param config {Object} Object literal specifying tabview configuration properties.
                             *
                             * @class Tab
                             * @constructor
                             * @extends Widget
                             * @uses WidgetChild
                             */
                            Y.Tab = Y.Base.create('tab', Y.Widget, [Y.WidgetChild], {
                                BOUNDING_TEMPLATE: '<li></li>',
                                CONTENT_TEMPLATE: '<a></a>',
                                PANEL_TEMPLATE: '<div></div>',
                            
                                _uiSetSelectedPanel: function(selected) {
                                    this.get('panelNode').toggleClass(Y.TabviewBase._classNames.selectedPanel, selected);
                                },
                            
                                _afterTabSelectedChange: function(event) {
                                   this._uiSetSelectedPanel(event.newVal);
                                },
                            
                                _afterParentChange: function(e) {
                                    if (!e.newVal) {
                                        this._remove();
                                    } else {
                                        this._add();
                                    }
                                },
                            
                                _initAria: function() {
                                    var anchor = this.get('contentBox'),
                                        id = anchor.get('id'),
                                        panel = this.get('panelNode');
                            
                                    if (!id) {
                                        id = Y.guid();
                                        anchor.set('id', id);
                                    }
                                    //  Apply the ARIA roles, states and properties to each tab
                                    anchor.set('role', 'tab');
                                    anchor.get('parentNode').set('role', 'presentation');
                            
                                    //  Apply the ARIA roles, states and properties to each panel
                                    panel.setAttrs({
                                        role: 'tabpanel',
                                        'aria-labelledby': id
                                    });
                                },
                            
                                syncUI: function() {
                                    var _classNames = Y.TabviewBase._classNames;
                            
                                    this.get('boundingBox').addClass(_classNames.tab);
                                    this.get('contentBox').addClass(_classNames.tabLabel);
                                    this.set('label', this.get('label'));
                                    this.set('content', this.get('content'));
                                    this._uiSetSelectedPanel(this.get('selected'));
                                },
                            
                                bindUI: function() {
                                   this.after('selectedChange', this._afterTabSelectedChange);
                                   this.after('parentChange', this._afterParentChange);
                                },
                            
                                renderUI: function() {
                                    this._renderPanel();
                                    this._initAria();
                                },
                            
                                _renderPanel: function() {
                                    this.get('parent').get('panelNode')
                                        .appendChild(this.get('panelNode'));
                                },
                            
                                _add: function() {
                                    var parent = this.get('parent').get('contentBox'),
                                        list = parent.get('listNode'),
                                        panel = parent.get('panelNode');
                            
                                    if (list) {
                                        list.appendChild(this.get('boundingBox'));
                                    }
                            
                                    if (panel) {
                                        panel.appendChild(this.get('panelNode'));
                                    }
                                },
                            
                                _remove: function() {
                                    this.get('boundingBox').remove();
                                    this.get('panelNode').remove();
                                },
                            
                                _onActivate: function(e) {
                                     if (e.target === this) {
                                         //  Prevent the browser from navigating to the URL specified by the
                                         //  anchor's href attribute.
                                         e.domEvent.preventDefault();
                                         e.target.set('selected', 1);
                                     }
                                },
                            
                                initializer: function() {
                                   this.publish(this.get('triggerEvent'), {
                                       defaultFn: this._onActivate
                                   });
                                },
                            
                                _defLabelGetter: function() {
                                    return this.get('contentBox').getHTML();
                                },
                            
                                _defLabelSetter: function(label) {
                                    var labelNode = this.get('contentBox');
                                    if (labelNode.getHTML() !== label) { // Avoid rewriting existing label.
                                        labelNode.setHTML(label);
                                    }
                                    return label;
                                },
                            
                                _defContentSetter: function(content) {
                                    var panel = this.get('panelNode');
                                    if (panel.getHTML() !== content) { // Avoid rewriting existing content.
                                        panel.setHTML(content);
                                    }
                                    return content;
                                },
                            
                                _defContentGetter: function() {
                                    return this.get('panelNode').getHTML();
                                },
                            
                                // find panel by ID mapping from label href
                                _defPanelNodeValueFn: function() {
                                    var _classNames = Y.TabviewBase._classNames,
                                        href = this.get('contentBox').get('href') || '',
                                        parent = this.get('parent'),
                                        hashIndex = href.indexOf('#'),
                                        panel;
                            
                                    href = href.substr(hashIndex);
                            
                                    if (href.charAt(0) === '#') { // in-page nav, find by ID
                                        panel = Y.one(href);
                                        if (panel) {
                                            panel.addClass(_classNames.tabPanel);
                                        }
                                    }
                            
                                    // use the one found by id, or else try matching indices
                                    if (!panel && parent) {
                                        panel = parent.get('panelNode')
                                                .get('children').item(this.get('index'));
                                    }
                            
                                    if (!panel) { // create if none found
                                        panel = Y.Node.create(this.PANEL_TEMPLATE);
                                        panel.addClass(_classNames.tabPanel);
                                    }
                                    return panel;
                                }
                            }, {
                                ATTRS: {
                                    /**
                                     * @attribute triggerEvent
                                     * @default "click"
                                     * @type String
                                     */
                                    triggerEvent: {
                                        value: 'click'
                                    },
                            
                                    /**
                                     * @attribute label
                                     * @type HTML
                                     */
                                    label: {
                                        setter: '_defLabelSetter',
                                        getter: '_defLabelGetter'
                                    },
                            
                                    /**
                                     * @attribute content
                                     * @type HTML
                                     */
                                    content: {
                                        setter: '_defContentSetter',
                                        getter: '_defContentGetter'
                                    },
                            
                                    /**
                                     * @attribute panelNode
                                     * @type Y.Node
                                     */
                                    panelNode: {
                                        setter: function(node) {
                                            node = Y.one(node);
                                            if (node) {
                                                node.addClass(Y.TabviewBase._classNames.tabPanel);
                                            }
                                            return node;
                                        },
                                        valueFn: '_defPanelNodeValueFn'
                                    },
                            
                                    tabIndex: {
                                        value: null,
                                        validator: '_validTabIndex'
                                    }
                            
                                },
                            
                                HTML_PARSER: {
                                    selected: function() {
                                        var ret = (this.get('boundingBox').hasClass(Y.TabviewBase._classNames.selectedTab)) ?
                                                    1 : 0;
                                        return ret;
                                    }
                                }
                            
                            });