Tip to generate fresh thumbnails for old bookmarks Rated 5 out of 5 stars
So, I thought I'd be a good Samaritan and leave a tip for anyone who might use this awesome addon:
Here's how to generate thumbnails for pre-existing bookmarks (ones you made before installing this addon) which can be time-consuming, but might be useful. First check the "Fetch missing thumbnails automatically" option in Preferences. Then by loading any of your old bookmarks in a tab, a fresh thumbnail will be created for that bookmark.
To make them faster, you can open multiple bookmarks in background tabs and then close them all once their images are auto-generated.