ExtJS 4 window with no initial size

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">

JavaScript

Ext.onReady(function() {
    new Ext.window.Window({
        resizable: true,
        height:300,
        width:400,
        layout: {
            type: 'hbox',
            align: 'stretch'
        },
      items: [{
        xtype: 'panel',
        title: 'Inner Panel One',
          border:0,
         flex: 6
    },{
        xtype:'splitter'
   },{
        xtype: 'panel',
        title: 'Results',
           border:0,
       flex: 4
    }]
    }).show();
});