setTitle doesn't update the title on a collapsed region in a border layout. This works in 4.0.7.

Code:
Ext.onReady(function() {
    var count = 1;

    var panel = Ext.create('Ext.panel.Panel', {
        height: 200,
        layout: 'border',
        renderTo: Ext.getBody(),
        width: 200,
        items: [
            {
                region: 'center',
                items: {
                    text: 'Update',
                    xtype: 'button',
                    handler: function() {
                        Ext.getCmp('west').setTitle('Count: ' + count++);
                    }
                }
            }, {
                collapsed: true,
                collapsible: true,
                id: 'west',
                region: 'west',
                title: 'West',
                width: 100
            }
        ]
    });
});