ExtJS 4 hbox (toolbars) 2

Trying to get a window with vbox/hbox layout to automatically compute a reasonable size.

by kzoon

HTML

<link rel="stylesheet" href="http://cdn.sencha.io/ext-4.0.7-gpl/resources/css/ext-all.css">

CSS

/* tabPanel header*/
.simple-selector .x-tab-bar-top{

    margin-right:60px!important;
}
/* */
.simple-selector .x-panel-body{border-top:0px!important;}


 .simple-selector .selected-panel{
    margin-top:12px!important;
    /*border-width:1px!important;
   border-style:solid!important;*/
    
}
.icon-selector-add              {
    background-image:url('../resources/themes/images/default/form/trigger.gif') !important;
}

JavaScript

Ext.onReady(function() {
    var treestore = Ext.create('Ext.data.TreeStore', {
        root: {
            expanded: true,
            children: [
                {
                text: "World",
                expanded: true,
                children: [
                    {
                    text: "North America",
                    leaf: false},
                {
                    text: "Asia",
                    leaf: false},
                {
                    text: "South America",
                    leaf: false},
                {
                    text: "Europe",
                    leaf: false}
                ]}
            ]
        }
    });

    new Ext.window.Window({
        resizable: true,
        height: 450,
        width: 700,
        cls: 'simple-selector',
        layout: {
            type: 'vbox'
            //,align:'stretch'
        },
        buttons: [{
            text: "Ok"},
        {
            text: "Apply"},
        {
            text: "Cancel"}],
        bodyStyle: 'padding:10px;',
        items: [
            {
            xtype: 'combobox',


            fieldLabel: 'Dimension'},
        {
            xtype: 'combobox',
            fieldLabel: 'Stored Selection'},
        {
            xtype: 'combobox',
            fieldLabel: 'Hierarchy'},
        {
            xtype: 'combobox',
            fieldLabel: 'Label'},
        {
            xtype: 'tbspacer',
            height: 15},
        {
            id: 'detailsContainer',
            xtype: 'container',
            width: '100%',
            flex: 1,
            layout: {
                type: 'hbox',
                align: 'stretch'

            },

            items: [

                {
                id: 'mytabpanel',
                xtype: 'tabpanel',
                title: false,
                border: 0,
                plain: true,
                flex: 5,
                items: [
                    {
                    xtype: 'panel',
            ...