before:
new Action('io.ox/mail/actions/compose', {
id: 'compose',
requires: function () {
....
});
---
after:
new Action('io.ox/mail/actions/compose', {
requires: function () {
....
});

hint: for some more examples take a look at
http://oxpedia.org/wiki/index.php?title=AppSuite:Extending_the_UI_(best_pr actices)