silverstripe-blog/code/admin/GridFieldFormAction.php

<?php

class GridFieldFormAction extends GridField_FormAction {
	/**
	 * @var array
	 */
	protected $extraAttributes = array();

	/**
	 * @param array $attributes
	 */
	public function setExtraAttributes(array $attributes) {
		$this->extraAttributes = $attributes;
	}

	/**
	 * @return array
	 */
	public function getAttributes()
	{
		$attributes = parent::getAttributes();

		return array_merge(
			$attributes,
			$this->extraAttributes
		);
	}
}