2028072 - www.facebook.com - Attempting to comment inside a post causes glitches after each letter typed in the input comment field

Status: RESOLVED FIXED

(Web Compatibility :: Site Reports, defect, P1)

Description

[Raul Bucata]

Environment:
Operating system: Android 14
Firefox version: Firefox 151.0

Steps to reproduce:

1. Navigate to: https://www.facebook.com/
2. Perform account login
3. Open a post
4. Type inside the comment input box and observe

Expected Behavior:
Typing letters causes no issues

Actual Behavior:
Typing letters causes glitches in the page

Notes:

• Reproduces regardless of the status of ETP
• Reproduces in firefox-nightly, and firefox-release
• Does not reproduce in chrome

Created from https://github.com/webcompat/web-bugs/issues/214434

Comment 1

[Raul Bucata]

In Chrome, the keyboard collapses after the first attempt, and no glitches are present anymore.

Comment 2

[Raul Bucata]

Attachment: Chr vs ff

Comment 3

[Hsin-Yi Tsai (she/her) [:hsinyi]]

Hi Jan, can you help investigate this? Thanks.

Comment 4

[Simon Farre [:sfarre]]

I'll take a look :hsinyi

Comment 5

[Simon Farre [:sfarre]]

I'm looking at this, but I'm NI'ing two who has touched or reviewed what I think may be relevant for this bug; just asking, is there anything that comes to mind that could cause this behavior on facebook? It seems like it could be the virtual keyboard doing something it shouldn't, but I'm not entirely sure.

Comment 6

[Simon Farre [:sfarre]]

So parts of facebook issues is definitely caused by the dynamic toolbar; when animating it seems to be firing a lot of resize events. Turning that off makes the site more responsive and also doesn't turn warp the input "widget" on the page. The widget gets elongated by the exact amount of the dynamic toolbar otherwise.

However, turning that off, still leaves us with the issue, that when inputting text and then hitting backspace, makes the thread "scroll jump down" until one is at the bottom. I have not yet been able to determine the cause of that bug (I can't reproduce just typing to make the page scroll, it is always just backspace)

Comment 7

[Emilio Cobos Álvarez [:emilio]]

I'm pretty sure this is due to the "Scroll to focused input" code: https://searchfox.org/firefox-main/rev/33682acc1fa0db34ac826b143048db28ee9f16a6/dom/base/nsDOMWindowUtils.cpp#2951

If the element is visible we shouldn't be scrolling anywhere, so it's probably a bug in the math there...

Also worth checking if this is a regression?

Comment 8

[Simon Farre [:sfarre]]

Thank you :emilio.

Bug 1947470 is the regressor.

Comment 9

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1947470

Comment 10

[Hiroyuki Ikezoe (:hiro)]

Geez, this one is also one of the bugs that I can't see the issue locally.

Can someone who can reproduce the issue post the link to a post where you can see the issue. I am on https://m.facebook.com/story.php?story_fbid=27011638605127452&id=183792915005385 but I don't see any scroll position jumps while typing.

Comment 11

[Hiroyuki Ikezoe (:hiro)]

Oops I saw a jump while I deleted a character in the input field. But now I can no longer see the jump. There's definitely a trigger but I have no idea right now.

Comment 12

[Hiroyuki Ikezoe (:hiro)]

Also can someone try to flip layout.scroll_fixed_content_into_view_visually to false and see if the issue still persists? It looks to me that in the recording in comment 2 there are two mixtures of different problems, 1) scroll position jumps, 2) the software keyboard closed suddenly? 1) is indeed a regression by bug 1947470, but the latter is unrelated to the bug. The pref disables the machinery introduced by bug 1947470.

Comment 13

[Hiroyuki Ikezoe (:hiro)]

Okay, I found a reliable way to reproduce the jump. That is: on https://m.facebook.com/story.php?story_fbid=791544977363614&id=1497163901777755 1) scroll to the middle of the scroll range 2) touch the "Write a comment" 3) The software keyboard appears, then touch the [x] key on the keyboard

Comment 14

[Simon Farre [:sfarre]]

:Hiro, just like you I can only reproduce differently from OP. I can reproduce only with backspace, when the input box is empty. When doing mozregression, I would start to also witness the jump scrolling while typing and when I got up to the regressor and past it the problem went away entirely.

Comment 15

[Hiroyuki Ikezoe (:hiro)]

Okay I confirmed this bug is no longer reproducible on a Fenix nightly based on this revision: https://treeherder.mozilla.org/jobs?repo=mozilla-central&revision=7a75e5d0dc02cefe2d13353043bd67fb5432df44