This is a great add-on that compliments Firefox well. Thank you to Geoff Lankow for developing it. To those who are having trouble with the "Capture Thumbnail" feature I had a couple of sites that weren't displaying thumbnails automatically. This is the procedure I followed to capture the thumbnails.

1. Open the new tab page and left click a tile without a thumbnail.
2. Go back to the new tab page, delete the tile and close the new tab page.
3. Go back to the tab displaying the page and apply the "Capture Thumbnail" function.
4. On the same page as (3) above apply the "Pin to the New Tab page" function.
5. Open the new tab page and the tile should be there with its thumbnail.

There may be other variants of this procedure that also work.

Regards to all.