I saw some discussion about this and it was CLOSED, but I'm having issues with this converting an ext 3.x app to 4.x.

Below is the code for the north region in a Viewport layout. Everything works except pack: 'center'. Each of the items are at the left of their containers. Just to see what would happen I changed it to pack: 'right' and there was no difference. Am I missing something?

Thanks

Dennis

Code:
Ext.create('Ext.container.Container', {        // north region
   region: 'north',
   id: 'clientTitle',
   baseCls: 'x-plain',
   margins: '10 0 0 0',
   height: 65, // give north region a height
   layout: {
      type: 'hbox',
      pack: 'center',
      align: 'middle'
   },
   items: [
      {
         xtype: 'container',
         flex: .5,
         autoEl: {
            cls:  'image',
            tag: 'img',
            src: '/images/my_image.png'
         }
      },
      {
         xtype: 'container',
         flex: 2,
         id : 'myTitle',
         autoEl: {
            tag: 'div',
            cls: 'title',
            html:'My Title'
         }
      },
      {
         xtype: 'container',
         flex: .5,
         autoEl: {
            tag: 'div',
            cls: 'version',
            html: 'test'
         }
      }
   ]
})