Created attachment 110311 [details]
How macOS Finder does it

We now have support for hiding and showing Places panel categories. Yay! However, the UI for this is rather hidden: you have to right-click on the header to hide it and its category, and then when you do, the entire thing--including the header--disappears, so you can easily forget about it or not even realize that there's anything hidden that can be shown!

I would recommend using a UI more similar to how the macOS Finder implements this: when you click on a header, its content collapses, the but the header remains, to show you that there's hidden content. It's quite slick.

Bonus: if we implement this, we can feasibly hide certain categories by default to reduce clutter (like "Search for") without impairing usability or discoverability because people can easily show it if they'd like.