public function definition_after_data() {
        $buttonarray = array();
        if (!$this->uistage->is_first_stage()) {
            $buttonarray[] = $this->_form->createElement('submit', 'previous', get_string('previousstage', 'backup'));
        } else if ($this->uistage instanceof backup_ui_stage) {
            // Only display the button on the first stage of backup, they only place where it has an effect.
            $buttonarray[] = $this->_form->createElement('submit', 'oneclickbackup', get_string('jumptofinalstep', 'backup'),
                array('class' => 'oneclickbackup'));
        }
        $buttonarray[] = $this->_form->createElement('cancel', 'cancel', get_string('cancel'), array('class' => 'confirmcancel'));
        $buttonarray[] = $this->_form->createElement(
            'submit',
            'submitbutton',
            get_string($this->uistage->get_ui()->get_name().'stage'.$this->uistage->get_stage().'action', 'backup'),
            array('class' => 'proceedbutton')
        );
        $this->_form->addGroup($buttonarray, 'buttonar', '', array(' '), false);
        $this->_form->closeHeaderBefore('buttonar');

        $this->_definition_finalized = true;
    }