newsupernova/vendor/magento/module-backend/view/adminhtml/templates/widget/button/split.phtml

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

// @codingStandardsIgnoreFile

?>
<?php
/** @var $block \Magento\Backend\Block\Widget\Button\SplitButton */
?>

<div <?= $block->getAttributesHtml() ?>>
    <button <?= $block->getButtonAttributesHtml() ?>>
        <span><?= $block->escapeHtml($block->getLabel()) ?></span>
    </button>
    <?php if ($block->hasSplit()): ?>
        <button <?= $block->getToggleAttributesHtml() ?>>
            <span>Select</span>
        </button>

        <?php if (!$block->getDisabled()): ?>
            <ul class="dropdown-menu" <?= /* @escapeNotVerified */ $block->getUiId("dropdown-menu") ?>>
                <?php foreach ($block->getOptions() as $key => $option): ?>
                <li>
                    <span <?= $block->getOptionAttributesHtml($key, $option) ?>>
                        <?= $block->escapeHtml($option['label']) ?>
                    </span>
                    <?php if (isset($option['hint'])): ?>
                    <div class="tooltip" <?= /* @escapeNotVerified */ $block->getUiId('item', $key, 'tooltip') ?>>
                        <a href="<?= $block->escapeHtml($option['hint']['href']) ?>" class="help">
                            <?= $block->escapeHtml($option['hint']['label']) ?>
                        </a>
                    </div>
                    <?php endif; ?>
                </li>
                <?php endforeach; ?>
            </ul>
        <?php endif; ?>
    <?php endif; ?>
</div>

<script type="text/x-magento-init">
    {
        ".actions-split": {
            "Magento_Ui/js/grid/controls/button/split": {}
        }
    }
</script>