Thumbnails with cover image for Windows/epub, djvu

[betelguese]

Hi all, I once was able in my previous Windows 7 PC to set Windows Explorer to be able to show the cover image (first page) of an ebook when Windows Explorer was set to Thumbnail View.

For PDF format I applied this fix, for mobi this one, but now I need to also extend thumbnail view to djvu and epub ebook formats and I don't recall how I managed to do it in Windows 7. Does anyone know how to do this? Thanks.

(since I have a backup of my previous Windows 7 PC, is there a way to export the corresponding registry keys and import them in my current Windows 8.1 PC?)