Tab list scroll position starts from the oldest instead of the newest (Regression)

[krokofant]

Steps to reproduce

1. Open 100+ tabs (might be visible with less as well)
2. Open your newest normal tab
3. Switch to incognito and open a new tab
4. Switch back to the normal tab list

Expected behavior

The tab list scroll position should start from the newest, at the bottom, as previous versions.

Actual behavior

The tab list scroll position starts from the oldest, at the top.
This means i need to scroll a long way down to get to my newest tabs.

Device information

• Device vendor / model and Android version: LGV30 Android 9
• Firefox for Android version: Nightly 210424 17:00 (Build #2015806539)

┆Issue is synchronized with this Jira Task

[SoftVision-LorandJanos]

Hi @krokofant ! Thank you for your report! I can reproduce this issue on latest Nightly (210426 05:02 - GV90) and Nightly (210424 17:00). Opened over 100 tabs and observed the behavior after taking the steps described above. Actual result at my end was the 100th tab going to the top each time I do the steps.
Device used: Motorola Nexus 6 with Android 7.1.1.

[stale]

See: #17373 This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[mariansima]

This issue still occurs on Samsung Galaxy A8 (Android 9) with Firefox Nightly 95.0a1 2021-11-01

[marcel263]

This is reproducable at least with tab grid.

Having interacted with private tabs, after which returning to normal tab tray, the last known scroll position i.e. selected tab is lost. Always scrolls to the top.

This behavior of forgetting the normal tab inconveniences common workflow for private tabs that were created from normal tabs ("open link in private tab" long-press menu option), e.g. a quick link check for untrusted domains, reading paywalled sites. Alas, a user might spend more time scrolling back to their last normal tab than they spent interacting with private tab, only becoming more impractical as one's tab count grows.

In short, normal tab position is always reset to the top after opening/creating private tabs while returning to normal tab tray. This behavior is inconsistent from the behavior when user merely switches between modes without any interaction, in that case normal tab tray position is remembered. Remembering last tab position (perhaps without selecting/opening, just scrolling) is beneficial for quick switching between modes.

edit: for reference, tested in chromium 89 this workflow of creating private tab from normal tab and returning to its 'parent' normal tab. Chromium remembers tab list scroll position in this case. Unfortunately no screencast due to security policy.

[chartmix]

Position sometimes gets also lost when in normal mode. Goes up to the top instead of the last position.

[chartmix]

Is there any update?
It is annoying to scroll so much because of the bug.

[bigConifer]

Looks like this is related to #23584.

See #23584 (comment).

[boek]

Moved to bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1812879

Change performed by the Move to Bugzilla add-on.