    /**
     * @class Ext.ComponentManager
     * @extends Ext.AbstractManager
     * <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#id 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 {@link Ext.Component#xtype 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 <code>{@link Ext.Component#xtype xtype}</code> 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 <code>{@link Ext.Component#xtype xtypes}</code>, see {@link Ext.Component}.</p>
     * @singleton
     */
    Ext.define('Ext.ComponentManager', {
        extend: 'Ext.AbstractManager',
        alternateClassName: 'Ext.ComponentMgr',

        singleton: true,

        typeName: 'xtype',

        /**
         * 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 {Constructor} defaultType 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 instanceof Ext.AbstractComponent) {
                return component;
            }
            else if (Ext.isString(component)) {
                return Ext.createByAlias('widget.' + component);
            }
            else {
                var type = component.xtype || defaultType,
                    config = component;

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

        registerType: function(type, cls) {
            this.types[type] = cls;
            cls[this.typeName] = type;
            cls.prototype[this.typeName] = type;
        }
    });