Auto-scroll on new messages is broken on certain monitor setups

[anoadragon453]

Description

I only notice this behaviour on my external monitor (1920x1080), but not on my Laptop screen (2560x1440). I find that:

• Scrolling to the bottom of room does not dismiss the "scroll-to-bottom" button in the bottom right corner.
• Sending a message does not scroll the room timeline to the bottom.

For example, I've used my scroll-wheel to scroll to the bottom of this room, but the scroll-to-bottom button is still showing, and still thinks there's a message hidden.

Moving the window to my Laptop screen and scrolling up and down dismisses the indicator.

I had a similar problem back in https://github.com/vector-im/element-web/issues/9342, though I'm not sure where the JS snipped went to test whether I'm having a non-int scrollTop value again.

Unlike the bug mentioned, this happens in all rooms.

Logs being sent: yes

Version information

• Platform: desktop
• OS: Manjaro Linux
• DE: GNOME3
• Version: Element nightly 2020081601

[anoadragon453]

@clokep noticed this behaviour as well while zoomed in a fair bit on his Element instance.

[clokep]

@clokep noticed this behaviour as well while zoomed in a fair bit on his Element instance.

After a bit of testing it seems that zooming a bit (Ctrl++) causes this be reproduced. (I had also increased the font size, but that seems unrelated after reverting it to normal.)