Thumbnail functionality was news to me but this post intrigued me to taker a closer look. This has been addressed in previous topics.
Check here:
Key points:
- file needs to be generated newly from 0.9.14 or newer
- you can’t have manually set Windows file association as this apparently messes up the required configuration
- you need to set Explorer view to icon or larger for this to work.
I never noticed thumbnails in Mac when I previously worked in that environment nor have I tried this in Linux.