@shukino

The following code works for me in GA:

Code:
Ext.application({
    name: 'Sencha',

    launch: function() {
        Ext.Viewport.add({
            top: 10,
            left: 10,
            width: 100,
            height: 100,
            modal: true,
            zIndex: 999,
            style: 'background:red'
        });
    }
});