adding custom extension archives thumb support?

[Owyn]

I'd like to have a way to turn previews on for .ugoira extension (pixiv animation format) (zip archive with jpeg files)

example (inside zip archive):
95973632_ugoira1920x1080.zip

[fire-eggs]

I see. I'll consider adding the ability to add additional extensions - ugoira == zip == cbz.

[I'm used to seeing ugoira files as uploaded on Danbooru, which are just ZIP files. I wasn't aware they were packaged with their own extension.]

[Owyn]

their own extension

well, some image viewers (honeyview for example) can play this extensions animation like that

[crisalis2]

I'm also interested in this, since many file formats are just ZIP and I'd like some of them to show a thumbnail (for example an hypothetical custom .htmlz format, .htmlz files consisting of two zipped files, something.html and cover.jpg), but not the generic .zip files. This is so easy to do on Linux, I miss that on Windows :-(