Another issue I see after simply adding the expand/collapse toggle....
You may have noticed some Twitter feeds in that sample River.
My system does auto-discovery of RSS including Twitter's RSS (which Twitter is removing in March, sadly).
In a River, the tweets are there as headlines intermixed with other feeds but their is a "Get Tweet" button that pulls in the "embedded Tweet" from Twitter's oembed endpoint.
The problem is, I chose to make this a manual request instead of loading multiple tweets at once to avoid prematurely reaching API limits.
It's also difficult to expand all and decipher twitter items from that same function.
I'll leave in the expand/collapse link regardless but it turns out its more complex in my system ;-)
I suppose I should just remove my Twitter support from Rivers.
M