Here's an idea: if a topic only has a new post from a user on my Ignore list (I'm talking about you ChartBuddy), it shouldn't show up on my Watchlist.
I like the sound of it. The problem is, it involves two things (user ignore, and the watchlist) that aren't present in my branch of SMF. There's no harm in posting ideas that I can't currently work on, though: I expect that I'll be able to work on them at some point.I really, really hate the trend of having to guess the meaning of icons (and that's a lot worse on any "modern" website than it is on Bitcointalk).
Yeah, I know just what you mean. 
But, in this case there's actually an icon-legend at the bottom of the page:
Will that also work on very long topics?
I think so. Behind the scenes it just makes the SQL query (that retrieves the posts) strictly more selective. The pagination and everything else will work like it normally does. Maybe there's some effect that I haven't accounted for, but, I'll probably be able to work around it if I bump into performance problems. It's actually an old patch (October 2022) that I'm re-working: When I originally sent it to theymos I'd only been on the forum for 4 months, so, I get why he didn't make time back then to carefully consider it. (Anyone else feel mildly embarrassed after reading their old posts/PMs?) 