button_split_box
Github

	function button_split_box() {
		return _class('html')->button_split_box('input_name', ['k1' => 'key1', 'k2' => 'key2']);
	}
	function button_split_box($name, $values = [], $selected = '', $extra = []) {
		$extra['button_split'] = true;
		return $this->button_box ($name, $values, $selected, $extra);
	}