Using TT-RSS feeds, I noticed the "New Subscription" button is not grey'd out when you click on a feed.
But if you click on "Unread" or "Important" then the New Subscription button can be used but it doesn't seem to do anything. I add a feed, it says "Updating (feed)" but the feed never appears in the list. After I exit TT-RSS and start it up, the feed is still not visible.
Not sure if this is intended or not. I mean, I can always add the feed through TT-RSS, I was just curious.