Rustdoc paragraphs are sometimes individually scrollable

[danielkeller]

On Firefox and MacOS, the individual paragraphs in item documentation sometimes scroll internally. This appears to happen when the cursor is on the top or bottom row of pixels of the paragraph, right where the cursor changes to a text cursor. If I remove the overflow-x: auto set on the paragraphs, the problem goes away.

[GuillaumeGomez]

Do you have a URL so I can test it locally (and also a screenshot to see where precisely)?

[ehuss]

I have bisected this to #88824. There are a lot of rustdoc changes in that rollup, though.

It only seems to happen for me in Firefox (96.0.1). It doesn't seem to happen in Safari or Chrome.

Here is a screen capture:

[GuillaumeGomez]

I see, thanks!

[ehuss]

FWIW, this is possibly a Firefox bug. I also notice this happening in the GitHub diff viewer. I tried searching for an issue related to this, but I couldn't find one. However, I am not very familiar with Firefox issue tracking.

I also tried Firefox 98.0a1 (2022-01-14) nightly, and it is still happening.

It's hard to explain what triggers it. The mouse cursor has to be at certain positions, but I can't tell what is special about them.

[Funky185540]

I noticed this behavior, too. I can reproduce it on:

• Firefox, version 96.0.3
• Tor, version 11.0.4 (based on Firefox 91.5.0esr)

It does not happen on:

• Epiphany, version 41.3 (i.e. GNOME Web)

Which makes a Bug in Firefox all the more likely.

[robjtede]

I did notice this but it seems to be fixed in the latest nightly Firefox build. I can reproduce on stable Firefox on the walkdir page that @ehuss referenced but not on nightly.

Regardless, it can be prevented pretty easily with overflow-y: hidden.

[GuillaumeGomez]

I can't reproduce it so I assume it was fixed. Please don't hesitate to reopen with an URL where it can be checked if it's not the case.