Alter the login form.

test.plugin.php

<?php
	public function action_modify_form_habari_login(FormUI $form) {
		// Remove the reset message
		$form->remove($form->reset_message);
		// Create a ul wrapper that wraps its children in li's
		$buttons = $form->append(FormControlWrapper::create('buttons')->set_setting('wrap_element', 'ul')->set_setting('wrap_each', '<li>%s</li>'));
		// Move the login button from the dropbutton to the button wrapper we just created
		$form->move_into($form->login, $buttons);
		// Remove the dropbutton
		$form->remove($form->submit_button);
		// Add a Register button
		$buttons->append(FormControlSubmit::create('register')->set_caption('Register?')->on_success(function(){ }));
		// Move the reset button into the button wrapper we created
		$form->move_into($form->reset_button, $buttons);
		// Remove the javascript links
		$form->remove($form->reset_link);
		$form->remove($form->login_link);

		// Insert a fieldset before the label for the username field
		$form->insert($form->label_for_habari_username, $inputs = FormControlFieldset::create('inputs'));
		// Move the username label (and the input control inside it) into the created fieldset
		$form->move_into($form->label_for_habari_username, $inputs);
		// Move the password label (and the input control inside it) into the created fieldset
		$form->move_into($form->label_for_habari_password, $inputs);

		// Add "foo" as a class to all of the buttons in the buttons wrapper
		$buttons->each(function(FormControl $control){
			$control->add_class('foo');
		});
	}