newsupernova/app/code/Magefan/Blog/Block/Adminhtml/Edit/CreateButton.php

<?php
/**
 * Copyright © 2016 Ihor Vansach (ihor@magefan.com). All rights reserved.
 * See LICENSE.txt for license details (http://opensource.org/licenses/osl-3.0.php).
 *
 * Glory to Ukraine! Glory to the heroes!
 */
namespace Magefan\Blog\Block\Adminhtml\Edit;

use Magento\Framework\View\Element\UiComponent\Control\ButtonProviderInterface;

/**
 * Button "Create" in "New Category" slide-out panel of a post page
 */
class CreateButton extends GenericButton implements ButtonProviderInterface
{
    /**
     * @return array
     */
    public function getButtonData()
    {
        return [
            'label' => __('Create'),
            'class' => 'save primary',
            'data_attribute' => [
                'mage-init' => ['button' => ['event' => 'save']],
                'form-role' => 'save',
            ],
            'sort_order' => 10
        ];
    }
}