NextGen Gallery: one thumbnail in sidebar link to complete slideshow

Using NextGen Gallery 1.8.1 w/ WP 3.1.3.

This seems simple but maybe I’m blind and can’t see how to do it.

I want to show one thumbnail in the sidebar widget that links to a slideshow of an entire gallery.

In the widget options, “show” (quantity) displays that number of thumbnails… then those link to a slideshow of that number of images.

Any guidance?

Thanks.