Room scroll can get stuck with last message hidden

[dbkr]

scroll up in a room, switch away from that room, switch back to that room, scroll down to the bottom. For me in matrix core just now, this hides my last message below the status bar. Switching away from the room whilst scrolled to the bottom, then switching back again, fixes it.

[ara4n]

i see this intermittently too. @richvdh don't suppose you remember what could cause this?

[richvdh]

Looks like geminiscrollbar thinks you are already scrolled all the way down; so this would imply some change that has made the content longer, with geminiscrollbar.update() not being called. In the past this has happened when things happen like images loading; but I thought we'd got all of them :/.

[lukebarnard1]

Since swapping to Quantum, I've realised what's going on here.

The "Jump to first unread message" is causing the timeline viewport to shrink, but no one tells the ScrollPanel that things have resized (like we do when events change content).

To avoid bugs like this, I have a fix that detects resizes in event tiles and the scroll panel that should fix this and similar bugs: matrix-org/matrix-react-sdk#1662

[t3chguy]

This is no longer relevant as we got rid of the typing indicator reserved margin