How to do something like 'up' from form success handler?

Newbie alert.

I am trying to write a authentication system using card layout. On successful submission of credentials, I want the success handler of my login form to do layout.setActiveItem('authenticated'). But, I have to be able to get the layout object.

I have tried a couple of things but nothing in the scope of the success handler seems to be able to access the component hierarchy. How is this meant to be done?

Code:

    buttons: ['->', {        text: 'Login',
        handler: function() {
            var frmLogin = this.up('form').getForm();
            if (frmLogin.isValid()) {
                frmLogin.submit({
                    url: '/user/session',
                    waitMsg: 'Submitting your credentials',
                    success: function(form, action) {
                        var panel = form.up('panel'); //form doesn't have an up method?