I had been asking for this for YEARS over on the PHT forum, and it just never happened. I'm a first-timer to Open PHT (since PHT functionality has been compromised with the new PMS version).
I'm THRILLED to see the ability to hide any in-episode thumbnails from unwatched episodes. Now I won't see character spoilers etc in the thumbnail before watching the episode!
GREAT stuff! Thank you, whoever implemented this long-wanted feature!