JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://dev.sencha.com/deploy/ext-4.0.0/resources/css/ext-all.css">

JavaScript

/**
 * Defines the test Window with common
 * configuration
 */
Ext.define('Demo.Window', {
    extend: 'Ext.window.Window',
    x: 10,
    width: 60,
    height: 100,
    title: 'Demo Window',
    defaults: {
        flex: 1
    },
    items: [{
        title: 'Panel 1',
    },{
        title: 'Panel 2',
    }]
});

/**
 * Correct configuration
 */
Ext.create('Demo.Window', {
    y: 10,
    layout: {
        type: 'hbox',
        align: 'stretch'
    }
}).show();

/**
 * Wrong configurations
 */
Ext.create('Demo.Window', {
    y: 120,
    layout: 'hbox',
    align: 'stretch'
}).show();

Ext.create('Demo.Window', {
    y: 230,
    layout: 'hbox',
    layoutConfig: {
        align: 'stretch'
    }
}).show();