Sometimes scrolling (up) does not work

[HarHarLinks]

Description

Rolling my mouse wheel to go back in the timeline, but it doesn't work reliably?

Steps to reproduce

• I'm visiting a couple public, federated rooms that were active over what is night for me
• there's the jump to last unread button
• try scrolling a bit
• nothing
• move mouse around for a bit, did element freeze?
• try scrolling here and there
• for some reason is scrolls when pointer is here, but not there
• eventually it works normally
• ???

could actually be a performance or backfilling issue?

Logs being sent: no

Version information

• Platform: desktop

For the desktop app:

• OS: Arch
• Version: aur/element-desktop-nightly-bin 2021060802-1

[germain-gg]

I have spent a bit of time trying to reproduce this issue without much luck so far.

If it does happen to you again, would you mind rageshaking as it might unveil some precious detail to debug

In the mean time a few questions to understand a bit more where that could come from

• Did that happen right after you launched Element or did you left it on overnight?
• Have you experienced it again after that time?

[HarHarLinks]

• it was shortly after launching
• i'm keeping an eye on it, so far i don't think it happened again

my intuition is that it is a performance problem of element and/or my (own, somewhat slow) homeserver. it might have been backfilling history at the point, but unlucky content somehow that the spinner wasn't visible?

[rkfg]

Happens to me as well on current develop. An easy way to reproduce when you have unread messages:

• click "Jump to first unread message"
  
• scroll works there
• click "Scroll to most recent messages":
  
• scroll locks up; move the mouse around while scrolling, after some time it randomly unlocks. Often locks up again when you scrolled to the last message.

Note: it only applies to scrolling using mouse wheel, it's always possible to drag the scroll bar handle but it's very inconvenient.

[germain-gg]

Would you be able to share a bit more information regarding your spec (OS, Browser, version, ...)
And if possible a rageshake could potentially help to unveil some important bits to resolve this

Thank you

[rkfg]

Using Brave 1.24.86 Chromium: 90.0.4430.212 (Official Build) (64-bit) on Debian testing. Reproducible on develop (https://develop.element.io/#/room/#matrix:matrix.org). Rageshake logs sent.

[HarHarLinks]

thanks for helping track this down, rkfg

it happened again to me just now, rageshake submitted. notice I did not use the go to unread nor go to most recent buttons, just load the room. element has been running for several hours before it.

[rkfg]

Yes, it happens sometimes even after switching between rooms. Then when I scroll it eventually start scrolling as if I'm trying to scroll through some invisible space (?) below the page. I just literally scroll for a long time, not even moving the mouse and the timeline starts moving after a while. Looks very weird.

[HarHarLinks]

Currently happening to me, again in TWIM room. Clicked "scroll up to last unread" and it's stuck (without going there). Clicked submit feedback then debug log, but that isn't popping up either now i can't even click submit feedback.

It "unlocked", I scrolled up slightly and back down, stuck again.

[jryans]

What about keyboard scrolling actions like page up / page down, do they still work in the locked case?

[rkfg]

PageUp/PageDown do work while mouse wheel doesn't.

[jryans]

Hmm, I wonder if this was triggered by the recent scrolling change in matrix-org/matrix-react-sdk#5823...

[jryans]

I think I can replicate this when testing in Chrome Canary on macOS with a mouse wheel, though it's a bit of a subtle issue.

[HarHarLinks]

Have you tested using a federated room? It happens in particular almost every time I open https://matrix.to/#/#thisweekinmatrix:matrix.org from my somewhat underpowered private homeserver (there is a backlog of unread messages that start out of screen for me 99% of cases).

I can confirm PageUp/PageDown do work while mouse wheel doesn't. Additionally, after using PageUp once, then using the wheel works. It is only when going back to the very bottom while there are still unread messages that it sticks there again. Scrolling back down too quickly will skip marking some unread messages as read by/for me (green line is supposedly where other participants would see my avatar icon?), and it stays sticky.

[jryans]

Hmm, still having trouble reproducing this consistently... 😕 I don't think it would be related to federated rooms, server performance, or anything like that...

[HarHarLinks]

It has now for the first time happened on a room internal to my hs. As before, I need only open the room which has had enough activity while I was away to offer the jump to first unread button and scrolling is stuck.

BTW, the "ignore and just mark everything as read" button also works to un-stick things.

My platform as mentioned above is (Arch) Linux, but I will add that I use the desktop app nightly through xwayland on wayland (swaywm) and pipewire, perhaps this is some weird edge case with this setup.

[rkfg]

I don't think it's platform-dependent. I'm on Debian with just plain Xorg and AwesomeWM and it still happens.

[mserajnik]

This happens to me with my self-built Element Desktop (Electron v13.1.2) as well after updating to v1.7.31 (matrix-react-sdk v3.24.0). It did not happen with v1.7.29 (matrix-react-sdk v3.22.0), which I used previously. I'm using Arch Linux with herbstluftwm, though I also think it's platform-independent, giving the different reports here.

I can't reliably reproduce it, it seems to happen randomly after new messages have been posted. What I can say is that dragging the scrollbar still works when this happens and doing that usually makes scrolling with the mouse wheel work again too.
Actually, never mind, it behaves exactly as described here for me as well.

Hmm, I wonder if this was triggered by the recent scrolling change in matrix-org/matrix-react-sdk#5823...

Giving that this issue definitely didn't exist with Element v1.7.29 (or at least, never happened to me with that or any prior version, and I use Element extensively 8+ hours daily), that sounds like a reasonable guess to me, because this was merged after that release.

[novocaine]

@HarHarLinks is this still happening?

[rkfg]

Can't reproduce here, at least with the steps I described above. And I don't remember it happening for a while already. Thanks!

[novocaine]

Hrm okay, if anyone still sees it we will reopen. Closing for now.