    /**
     * @class Ext.container.Container
     * @extends Ext.container.AbstractContainer
     * <p>Base class for any {@link Ext.Component} that may contain other Components. Containers handle the
     * basic behavior of containing items, namely adding, inserting and removing items.</p>
     *
     * <p>The most commonly used Container classes are {@link Ext.panel.Panel}, {@link Ext.window.Window} and {@link Ext.tab.Panel}.
     * If you do not need the capabilities offered by the aforementioned classes you can create a lightweight
     * Container to be encapsulated by an HTML element to your specifications by using the
     * <code><b>{@link Ext.Component#autoEl autoEl}</b></code> config option.</p>
     *
     * {@img Ext.Container/Ext.Container.png Ext.Container component}
     * <p>The code below illustrates how to explicitly create a Container:<pre><code>
    // explicitly create a Container
    Ext.create('Ext.container.Container', {
        layout: {
            type: 'hbox'
        },
        width: 400,
        renderTo: Ext.getBody(),
        border: 1,
        style: {borderColor:'#000000', borderStyle:'solid', borderWidth:'1px'},
        defaults: {
            labelWidth: 80,
            // implicitly create Container by specifying xtype
            xtype: 'datefield',
            flex: 1,
            style: {
                padding: '10px'
            }
        },
        items: [{
            xtype: 'datefield',
            name: 'startDate',
            fieldLabel: 'Start date'
        },{
            xtype: 'datefield',
            name: 'endDate',
            fieldLabel: 'End date'
        }]
    });
    </code></pre></p>
     *
     * <p><u><b>Layout</b></u></p>
     * <p>Container classes delegate the rendering of child Components to a layout
     * manager class which must be configured into the Container using the
     * <code><b>{@link #layout}</b></code> configuration property.</p>
     * <p>When either specifying child <code>{@link #items}</code> of a Container,
     * or dynamically {@link #add adding} Components to a Container, remember to
     * consider how you wish the Container to arrange those child elements, and
     * whether those child elements need to be sized using one of Ext's built-in
     * <b><code>{@link #layout}</code></b> schemes. By default, Containers use the
     * {@link Ext.layout.container.Auto Auto} scheme which only
     * renders child components, appending them one after the other inside the
     * Container, and <b>does not apply any sizing</b> at all.</p>
     * <p>A common mistake is when a developer neglects to specify a
     * <b><code>{@link #layout}</code></b> (e.g. widgets like GridPanels or
     * TreePanels are added to Containers for which no <code><b>{@link #layout}</b></code>
     * has been specified). If a Container is left to use the default
     * {Ext.layout.container.Auto Auto} scheme, none of its
     * child components will be resized, or changed in any way when the Container
     * is resized.</p>
     * <p>Certain layout managers allow dynamic addition of child components.
     * Those that do include {@link Ext.layout.container.Card},
     * {@link Ext.layout.container.Anchor}, {@link Ext.layout.container.VBox}, {@link Ext.layout.container.HBox}, and
     * {@link Ext.layout.container.Table}. For example:<pre><code>
    //  Create the GridPanel.
    var myNewGrid = new Ext.grid.Panel({
        store: myStore,
        headers: myHeaders,
        title: 'Results', // the title becomes the title of the tab
    });

    myTabPanel.add(myNewGrid); // {@link Ext.tab.Panel} implicitly uses {@link Ext.layout.container.Card Card}
    myTabPanel.{@link Ext.tab.Panel#setActiveTab setActiveTab}(myNewGrid);
     * </code></pre></p>
     * <p>The example above adds a newly created GridPanel to a TabPanel. Note that
     * a TabPanel uses {@link Ext.layout.container.Card} as its layout manager which
     * means all its child items are sized to {@link Ext.layout.container.Fit fit}
     * exactly into its client area.
     * <p><b><u>Overnesting is a common problem</u></b>.
     * An example of overnesting occurs when a GridPanel is added to a TabPanel
     * by wrapping the GridPanel <i>inside</i> a wrapping Panel (that has no
     * <code><b>{@link #layout}</b></code> specified) and then add that wrapping Panel
     * to the TabPanel. The point to realize is that a GridPanel <b>is</b> a
     * Component which can be added directly to a Container. If the wrapping Panel
     * has no <code><b>{@link #layout}</b></code> configuration, then the overnested
     * GridPanel will not be sized as expected.<p>
     *
     * <p><u><b>Adding via remote configuration</b></u></p>
     *
     * <p>A server side script can be used to add Components which are generated dynamically on the server.
     * An example of adding a GridPanel to a TabPanel where the GridPanel is generated by the server
     * based on certain parameters:
     * </p><pre><code>
    // execute an Ajax request to invoke server side script:
    Ext.Ajax.request({
        url: 'gen-invoice-grid.php',
        // send additional parameters to instruct server script
        params: {
            startDate: Ext.getCmp('start-date').getValue(),
            endDate: Ext.getCmp('end-date').getValue()
        },
        // process the response object to add it to the TabPanel:
        success: function(xhr) {
            var newComponent = eval(xhr.responseText); // see discussion below
            myTabPanel.add(newComponent); // add the component to the TabPanel
            myTabPanel.setActiveTab(newComponent);
        },
        failure: function() {
            Ext.Msg.alert("Grid create failed", "Server communication failure");
        }
    });
    </code></pre>
     * <p>The server script needs to return a JSON representation of a configuration object, which, when decoded
     * will return a config object with an {@link Ext.Component#xtype xtype}. The server might return the following
     * JSON:</p><pre><code>
    {
        "xtype": 'grid',
        "title": 'Invoice Report',
        "store": {
            "model": 'Invoice',
            "proxy": {
                "type": 'ajax',
                "url": 'get-invoice-data.php',
                "reader": {
                    "type": 'json'
                    "record": 'transaction',
                    "idProperty": 'id',
                    "totalRecords": 'total'
                })
            },
            "autoLoad": {
                "params": {
                    "startDate": '01/01/2008',
                    "endDate": '01/31/2008'
                }
            }
        },
        "headers": [
            {"header": "Customer", "width": 250, "dataIndex": 'customer', "sortable": true},
            {"header": "Invoice Number", "width": 120, "dataIndex": 'invNo', "sortable": true},
            {"header": "Invoice Date", "width": 100, "dataIndex": 'date', "renderer": Ext.util.Format.dateRenderer('M d, y'), "sortable": true},
            {"header": "Value", "width": 120, "dataIndex": 'value', "renderer": 'usMoney', "sortable": true}
        ]
    }
    </code></pre>
     * <p>When the above code fragment is passed through the <code>eval</code> function in the success handler
     * of the Ajax request, the result will be a config object which, when added to a Container, will cause instantiation
     * of a GridPanel. <b>Be sure that the Container is configured with a layout which sizes and positions the child items to your requirements.</b></p>
     * <p>Note: since the code above is <i>generated</i> by a server script, the <code>autoLoad</code> params for
     * the Store, the user's preferred date format, the metadata to allow generation of the Model layout, and the ColumnModel
     * can all be generated into the code since these are all known on the server.</p>
     *
     * @xtype container
     */
    Ext.define('Ext.container.Container', {
        extend: 'Ext.container.AbstractContainer',
        alias: 'widget.container',
        alternateClassName: 'Ext.Container',

        /**
         * Return the immediate child Component in which the passed element is located.
         * @param el The element to test.
         * @return {Component} The child item which contains the passed element.
         */
        getChildByElement: function(el) {
            var item,
                itemEl,
                i = 0,
                it = this.items.items,
                ln = it.length;

            el = Ext.getDom(el);
            for (; i < ln; i++) {
                item = it[i];
                itemEl = item.getEl();
                if ((itemEl.dom === el) || itemEl.contains(el)) {
                    return item;
                }
            }
            return null;
        }
    });