    /**
     * @private
     *
     * <p>Provides a registry of all Components (instances of {@link Ext.Component} or any subclass
     * thereof) on a page so that they can be easily accessed by {@link Ext.Component component}
     * {@link Ext.Component#getId id} (see {@link #get}, or the convenience method {@link Ext#getCmp Ext.getCmp}).</p>
     * <p>This object also provides a registry of available Component <i>classes</i>
     * indexed by a mnemonic code known as the Component's `xtype`.
     * The <code>xtype</code> provides a way to avoid instantiating child Components
     * when creating a full, nested config object for a complete Ext page.</p>
     * <p>A child Component may be specified simply as a <i>config object</i>
     * as long as the correct `xtype` is specified so that if and when the Component
     * needs rendering, the correct type can be looked up for lazy instantiation.</p>
     * <p>For a list of all available `xtype`, see {@link Ext.Component}.</p>
     */
    Ext.define('Ext.ComponentManager', {
        alternateClassName: 'Ext.ComponentMgr',
        singleton: true,

        constructor: function() {
            var map = {};

            // The sole reason for this is just to support the old code of ComponentQuery
            this.all = {
                map: map,

                getArray: function() {
                    var list = [],
                        id;

                    for (id in map) {
                        list.push(map[id]);
                    }

                    return list;
                }
            };

            this.map = map;
        },

        /**
         * Registers an item to be managed
         * @param {Object} component The item to register
         */
        register: function(component) {
            this.map[component.getId()] = component;
        },

        /**
         * Unregisters an item by removing it from this manager
         * @param {Object} component The item to unregister
         */
        unregister: function(component) {
            delete this.map[component.getId()];
        },

        /**
         * Checks if an item type is registered.
         * @param {String} component The mnemonic string by which the class may be looked up
         * @return {Boolean} Whether the type is registered.
         */
        isRegistered : function(component){
            return this.map[component] !== undefined;
        },

        /**
         * Returns an item by id.
         * For additional details see {@link Ext.util.HashMap#get}.
         * @param {String} id The id of the item
         * @return {Object} The item, undefined if not found.
         */
        get: function(id) {
            return this.map[id];
        },

        /**
         * Creates a new Component from the specified config object using the
         * config object's xtype to determine the class to instantiate.
         * @param {Object} config A configuration object for the Component you wish to create.
         * @param {Function} defaultType (optional) The constructor to provide the default Component type if
         * the config object does not contain a <code>xtype</code>. (Optional if the config contains a <code>xtype</code>).
         * @return {Ext.Component} The newly instantiated Component.
         */
        create: function(component, defaultType) {
            if (component.isComponent) {
                return component;
            }
            else if (Ext.isString(component)) {
                return Ext.createByAlias('widget.' + component);
            }
            else {
                var type = component.xtype || defaultType;

                return Ext.createByAlias('widget.' + type, component);
            }
        },

        registerType: Ext.emptyFn
    });