In the below example, the panel does not expand to the defined height of 200, but rather the content's defined 50. If the anchor layout is removed from the parent panel, it seems to work fine.

Code:
App = new Ext.Viewport({
  layout: "border",
  items: [
    {
      region: "center",
      border: false,
      layout: 'fit',
      items: [
        {
          border: false,
          layout: 'anchor',
          items: [
            {
              anchor: '100%',
              height: 200,
              collapsible: true,
              collapsed: true,
              title: 'Expand me!',
              items: [
                {
                  height: 50,
                  border: false,
                  html: "Content"
                }
              ]
            }
          ]
        }
      ]
    }
  ]
})