Items are arranged according to a `layout`.

- `layout:'fit'` 
- `layout: 'card'`
- `layout: 'vbox'`
- `layout: 'hbox'`
- `layout: 'flexbox'`

When you need to provide more config details, use this form:

    layout: {
        ntype:'vbox',
        align: 'stretch'
    }


The container base class imports all layouts, which means you
can use `ntype` (and don't need to explicitly import the layout class).

<span style="color: #bbbbbb;">And actually, in the case of layouts, you
<i style="color: #bbbbbb;">must</i> use ntype. You do not specify layouts 
using the <tt>module</tt> config.
</span>