The old reddit client I used had an option in the drop down menu to hide read posts. So say you were on the Frontpage, if you selected hide read, it would only hide the posts that were currently visible using your sort algorithm. So unread posts, and ant read posts that hadn't been loaded yet would still be there. You could use it on any view in any subreddit or multimedia, rather than just having one global option. There was also a way to 'unhindered posts, making it more like a toggle. That's what I'd like to see next if possible.