/**
                             * The TabView module
                             *
                             * @module tabview
                             */
                            
                            var DOT = '.',
                            
                                /**
                                 * Provides a tabbed widget interface
                                 * @param config {Object} Object literal specifying tabview configuration properties.
                                 *
                                 * @class TabView
                                 * @constructor
                                 * @extends Widget
                                 * @uses WidgetParent
                                 */
                                TabView = Y.Base.create('tabView', Y.Widget, [Y.WidgetParent], {
                            
                                _afterChildAdded: function() {
                                    this.get('contentBox').focusManager.refresh();
                                },
                            
                                _defListNodeValueFn: function() {
                                    var node = Y.Node.create(this.LIST_TEMPLATE);
                            
                                    node.addClass(Y.TabviewBase._classNames.tabviewList);
                            
                                    return node;
                                },
                            
                                _defPanelNodeValueFn: function() {
                                    var node = Y.Node.create(this.PANEL_TEMPLATE);
                            
                                    node.addClass(Y.TabviewBase._classNames.tabviewPanel);
                            
                                    return node;
                                },
                            
                                _afterChildRemoved: function(e) { // update the selected tab when removed
                                    var i = e.index,
                                        selection = this.get('selection');
                            
                                    if (!selection) { // select previous item if selection removed
                                        selection = this.item(i - 1) || this.item(0);
                                        if (selection) {
                                            selection.set('selected', 1);
                                        }
                                    }
                            
                                    this.get('contentBox').focusManager.refresh();
                                },
                            
                                _initAria: function(contentBox) {
                                    var tablist = contentBox.one(Y.TabviewBase._queries.tabviewList);
                            
                                    if (tablist) {
                                        tablist.setAttrs({
                                            //'aria-labelledby':
                                            role: 'tablist'
                                        });
                                    }
                                },
                            
                                bindUI: function() {
                                    //  Use the Node Focus Manager to add keyboard support:
                                    //  Pressing the left and right arrow keys will move focus
                                    //  among each of the tabs.
                            
                                    this.get('contentBox').plug(Y.Plugin.NodeFocusManager, {
                                                    descendants: DOT + Y.TabviewBase._classNames.tabLabel,
                                                    keys: { next: 'down:39', // Right arrow
                                                            previous: 'down:37' },  // Left arrow
                                                    circular: true
                                                });
                            
                                    this.after('render', this._setDefSelection);
                                    this.after('addChild', this._afterChildAdded);
                                    this.after('removeChild', this._afterChildRemoved);
                                },
                            
                                renderUI: function() {
                                    var contentBox = this.get('contentBox');
                                    this._renderListBox(contentBox);
                                    this._renderPanelBox(contentBox);
                                    this._childrenContainer = this.get('listNode');
                                    this._renderTabs(contentBox);
                                    this._initAria(contentBox);
                                },
                            
                                _setDefSelection: function() {
                                    //  If no tab is selected, select the first tab.
                                    var selection = this.get('selection') || this.item(0);
                            
                                    this.some(function(tab) {
                                        if (tab.get('selected')) {
                                            selection = tab;
                                            return true;
                                        }
                                    });
                                    if (selection) {
                                        // TODO: why both needed? (via widgetParent/Child)?
                                        this.set('selection', selection);
                                        selection.set('selected', 1);
                                    }
                                },
                            
                                _renderListBox: function(contentBox) {
                                    var node = this.get('listNode');
                                    if (!node.inDoc()) {
                                        contentBox.append(node);
                                    }
                                },
                            
                                _renderPanelBox: function(contentBox) {
                                    var node = this.get('panelNode');
                                    if (!node.inDoc()) {
                                        contentBox.append(node);
                                    }
                                },
                            
                                _renderTabs: function(contentBox) {
                                    var _classNames = Y.TabviewBase._classNames,
                                        _queries = Y.TabviewBase._queries,
                                        tabs = contentBox.all(_queries.tab),
                                        panelNode = this.get('panelNode'),
                                        panels = (panelNode) ? this.get('panelNode').get('children') : null,
                                        tabview = this;
                            
                                    if (tabs) { // add classNames and fill in Tab fields from markup when possible
                                        tabs.addClass(_classNames.tab);
                                        contentBox.all(_queries.tabLabel).addClass(_classNames.tabLabel);
                                        contentBox.all(_queries.tabPanel).addClass(_classNames.tabPanel);
                            
                                        tabs.each(function(node, i) {
                                            var panelNode = (panels) ? panels.item(i) : null;
                                            tabview.add({
                                                boundingBox: node,
                                                contentBox: node.one(DOT + _classNames.tabLabel),
                                                panelNode: panelNode
                                            });
                                        });
                                    }
                                }
                            }, {
                                ATTRS: {
                                    defaultChildType: {
                                        value: 'Tab'
                                    },
                            
                                    listNode: {
                                        setter: function(node) {
                                            node = Y.one(node);
                                            if (node) {
                                                node.addClass(Y.TabviewBase._classNames.tabviewList);
                                            }
                                            return node;
                                        },
                            
                                        valueFn: '_defListNodeValueFn'
                                    },
                            
                                    panelNode: {
                                        setter: function(node) {
                                            node = Y.one(node);
                                            if (node) {
                                                node.addClass(Y.TabviewBase._classNames.tabviewPanel);
                                            }
                                            return node;
                                        },
                            
                                        valueFn: '_defPanelNodeValueFn'
                                    },
                            
                                    tabIndex: {
                                        value: null
                                        //validator: '_validTabIndex'
                                    }
                                },
                            
                                HTML_PARSER: {
                                    listNode: function(srcNode) {
                                        return srcNode.one(Y.TabviewBase._queries.tabviewList);
                                    },
                                    panelNode: function(srcNode) {
                                        return srcNode.one(Y.TabviewBase._queries.tabviewPanel);
                                    }
                                },
                            
                                // Static for legacy support.
                                LIST_TEMPLATE: '<ul></ul>',
                                PANEL_TEMPLATE: '<div></div>'
                            });
                            
                            // Map to static values by default.
                            TabView.prototype.LIST_TEMPLATE = TabView.LIST_TEMPLATE;
                            TabView.prototype.PANEL_TEMPLATE = TabView.PANEL_TEMPLATE;
                            
                            Y.TabView = TabView;