I would like to see it added to the forum.
It's (spoiler: ███ ████████ ), it saves screen real estate, and of course, it can be used for actual spoilers.
i think this is a good idea, i've seen it on a few subreddits and it works really well. i did think of a couple potential problems with it though:
a) how would it work for mobile users?
b) sometimes spoilers are used to hide large amounts of code, and this wouldn't allow for that. it would be a nice feature to have though, especially on a bitcoin forum (i think that code might be posted in some sections especially the development sections)