Hi,

it's working for me if I put a height and minHeight to the children (ExtJS 4.2):

Code:
items:[
{
    xtype: 'container',
    layout: 'accordion', 
    overflowY: 'auto',
    items: [{ 
        title: 'first',
        height: 150,
        minHeight: 150,
        html: 'this is first<br>more content'
    },
    { 
        title: 'second',
        height: 150,
        minHeight: 150,
        html: 'this is a 2nd panel<br>more content<br>and more content'
    },
...