1941195 - HTML dropdown select wrong element after scrolling

Status: VERIFIED FIXED

(Core :: Panning and Zooming, defect, P2)

Description

[mone27]

Attachment: Screencast From 2025-01-12 14-09-25.mp4

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:136.0) Gecko/20100101 Firefox/136.0

Steps to reproduce:

Open a page with a long dropdown (e.g. https://mone27.net/ff-dropdown-bug)
Open the dropdown and the scroll with the mouse wheel

Actual results:

The cursor position and the selected element get out of line

This bugs has been reproduces on the latest nightly (136.0a1 (2025-01-11) (64-bit) on Linux), on the stable release this it is working as intended.

Expected results:

The selected element should be the one below the cursors

Comment 1

[Francesco Lodolo [:flod]]

Not sure if this is a graphics problem, or a Linux one. I can't reproduce on macOS.

Could you try running mozregression to help to identify the issue?
https://mozilla.github.io/mozregression/quickstart.html

Comment 2

[Alice0775 White]

I can reproduce the issue on Nightly136.0a1 Windows11.

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=39bdda0a157484f029b483a902e27e8e19b68b28&tochange=38d1226c547097a771905e876d958c67374d61a0

Comment 3

[mone27]

@Flod would you still like me to run mozregression on Linux?

Comment 4

[Francesco Lodolo [:flod]]

(In reply to mone27 from comment #3)

@Flod would you still like me to run mozregression on Linux?

No need, Alice already found the regression.

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

:hiro, since you are the author of the regressor, bug 1938840, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 6

[Alice0775 White]

And Regression window with apz.popups_without_remote.enabled = true;
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=8aec7b1b4272d50e21928ba57fff57af1909a778&tochange=8e8305f85074074769f6d51a556f210132f2c25b

Comment 7

[Hiroyuki Ikezoe (:hiro)]

I think the patch for bug 1941175 fixes this too.

Comment 8

[Bianca Hidecuti, Desktop Test Engineering [:bhidecuti]]

I was able to reproduce the issue on an affected Firefox Nightly 136.0a1 build from 2025-01-12, using Windows 11 and Ubuntu 22.04, while following the steps described in Comment 0.
Verified as fixed on Firefox 136.0b3 using Windows 11 and Ubuntu 22.04. The selected element is now the one below the cursor.