Clicking on the Room List section label doesn't allow to jump to the top of it anymore

[AmandineLP]

this is a problem as sometimes I end up having the room list scrolled quite far down (I think because I use search to find a room, and when I get into the room the room list scrolls down to where the room is), and I can't scroll back up quickly. Previously if the room list was scrolled down clicking on 'Rooms' would bring me back to the top of the list of rooms. Then I had to click on People then Favourites to eventually get back to my default preferred state (Favourites + People + Rooms displayed), which was painful enough. Now I have no choice but use the scroll bar which is even worse. One way to work around this could be to not make the room list scroll down to where the room is when I get into a room from search (it doesn't bring anything to do this).

[turt2live]

During a call earlier I thought this was about jumping down the room list, but indeed it's a bug that jumping up the room list is now different. It appears as though matrix-org/matrix-react-sdk#7991 may have broken this, somehow, in that reverting the PR restores almost-working functionality.

Before 7991:

1. Have lots of rooms under "Rooms" in your room list & show them all
2. Scroll down a bunch so that the "Rooms" header is sticky to the top of the room list
3. Click the "Rooms" header to try and scroll back up
4. Note the (side-quest) bug which meant the room list wouldn't jump all the way up, instead stopping somewhere in the 66-75% towards the top mark, requiring further (multiple) clicks. This behaviour was not introduced by Fix room list being laggy while scrolling 🐌 matrix-org/matrix-react-sdk#7939 or Fix accessibility around the room list treeview and new search beta matrix-org/matrix-react-sdk#7856 which would have been prime candidates for this. The cause is unknown.

After 7991:

1. Have lots of rooms under "Rooms" in your room list & show them all
2. Scroll down a bunch so that the "Rooms" header is sticky to the top of the room list
3. Click the "Rooms" header to try and scroll back up
4. Rooms section is collapsed instead of jumping up to the top

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From the call earlier, there is a separate bug where the "Low Priority" (or any header sicky to the bottom) has slightly weird behaviour post-7991:

• If already collapsed, it will scroll down and expand (most of the time - I couldn't figure out repro steps, but sometimes it'll expand without scrolling)
• If already expanded, it will collapse instead of scrolling down

Before 7991 the expected behaviour worked fine:

• If already collapsed, it will scroll without expanding.
• If already expanded, it will scroll without collapsing.

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It was also mentioned that matrix-org/matrix-react-sdk#6054 might help this situation in general.