Magento的。 如何扩展和使用默认产品图片上传器？

i have created my own grid in magento admin panel and add few tabs. In one tab i need to display same picture uploader like in creating product page.

I mean this block: Mage/Adminhtml/Block/Catalog/Product/Helper/Form/Gallery/Content.php

here is how i create the tab

$this->addTab('images_uploader', array(
        'label'     => Mage::helper('adminhtml')->__('Images Uploader'),
        'title'     => Mage::helper('adminhtml')->__('Images Uploader'),
        'content'   => $this->getLayout()->createBlock('adminhtml/catalog_product_helper_form_gallery_content')->toHtml(),
    ));

but i get error Call to a member function getDataObject() on a non-object app/code/core/Mage/Adminhtml/Block/Catalog/Product/Helper/Form/Gallery/Content.php on line 164