1925564 - [macOS] Sidebar vertical tabs scrollbar doesn't autohide and remains in hover state

Status: NEW

(Core :: Panning and Zooming, defect, P3)

Description

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

Attachment: video showing the issue

Found in

• 133.0a1 (2024-10-17)

Affected versions

• 133.0a1
• 132.0b8

Preconditions

• Have the “sidebar.revamp” pref set to true in about:config
• Have the sidebar.verticalTabs pref set to true in about:config

Tested platforms

• Affected platforms: macOS 14.7
• Unaffected platforms: Windows 11, Ubuntu 22.04

Steps to reproduce

1. Open multiple tabs so that the scrollbar is visible
2. Scroll down or up and hover over the scrollbar before it disappears
3. Move the cursor away and observe the behavior

Expected result

• The scrollbar should autohide

Actual result

• The scrollbar remains visible and in hover state

Regression range

• Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=de7bfa4d7c30ab51ace9eb7f3e30790515a30033&tochange=d2e1f0acc1ad19db478439b44064a14ebc4e18e0
• Unfortunately I cannot tell whether bug 1907592 or bug 1899582 is the actual regressor

Additional notes

• See the attached video
• The scrollbar does not disappear if moving the cursor from the tab strip (only after scrolling up and down again)

Comment 1

[Emilio Cobos Álvarez [:emilio]]

So this seems like an APZ bug. I logged scrollbar activity using a patch that I'm going to attach now, and it seems like apz never sends the transformend.

Comment 2

[Emilio Cobos Álvarez [:emilio]]

Attachment: Logging patch, for reference

Comment 3

[Emilio Cobos Álvarez [:emilio]]

Just for reference, this looks like a regular scroller but it's not... https://searchfox.org/mozilla-central/rev/4ac5b1f6cc9d8c186986f52369a2d9a537d10474/toolkit/content/widgets/arrowscrollbox.js#713 scrolls programmatically rather than letting Gecko do its thing.

Comment 4

[Botond Ballo [:botond]]

cc Dan who has recently worked on scrollend, which shares an underlying mechanism with the scrollbar activity tracker (transform-begin / transform-end notifications).

The regression window includes a change which (potentially) makes the affected scrolling operation an instant scroll -- maybe you've come across an issue related to a missing transform-end notification for a programmatic instant scroll?

Comment 5

[Donal Meehan [:dmeehan]]

Setting Bug 1907592 as the regressor based on Comment 0 and Comment 4. Can correct later if needed.
The depends on bug, Bug 1927132, is not something we would take in beta.
Setting Fx133 to wontfix but please let me know if there are any concerns with that.

Comment 6

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

:jsudiaman, since you are the author of the regressor, bug 1907592, could you take a look?

For more information, please visit BugBot documentation.

Comment 7

[Jonathan Sudiaman [:jsudiaman]]

This seems to be an issue with how <arrowscrollbox> handles vertical scrolling. We would either have to make a fix there, or use a different container, neither of which seems trivial. wontfix for 133 sounds right to me.

Comment 8

[Mathew Hodson]

Only encountered with the new sidebar and sidebar.revamp is disabled by default.