private void onSelection() {
        final User selected = userList.getSelectionModel().getSelected();
        if (selected != null) {
//            editButton.setTitle("Edit " + getDescription(selected));
//            editButton.setEnabled(true);
            deleteButton.setTitle("Delete " + getDescription(selected));
            deleteButton.setEnabled(true);
        } else {
//            editButton.setTitle("No Selection");
//            editButton.setEnabled(false);
            deleteButton.setTitle("No Selection");
            deleteButton.setEnabled(false);
        }
    }
For managing all the users (not groups)
stroom-core-client/src/main/java/stroom/security/client/presenter/UsersPresenter.java