1988384 - Vertical tab Sidebar does not auto hide if mouse does not leave Window

Status: RESOLVED DUPLICATE of bug 1985692

(Firefox :: Sidebar, defect)

Description

[Meron35]

Attachment: Screencast From 2025-09-13 09-54-50.mp4

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0

Steps to reproduce:

Enable Expand sidebar on hover, and open two different windows.
Arrange the windows so that they are overlapping, or next to each other in left/right direction.
Make the left window focused, and move the cursor to the right window's sidebar to expand its sidebar, then move the cursor back to the left window.

Actual results:

The right window's vertical sidebar stays expanded when moving the cursor back to the left window. This only happens if the cursor does not leave any windows, i.e. by making sure the two windows are separate/non overlapping.

Expected results:

The right window's vertical sidebar should auto hide when moving the cursor back to the left window.

Comment 1

[Monica Chiorean (OOO July 31st 5:30PM)]

I was able to reproduce the issue on Win11x64 using FF build 142.0.1(20250827004350).
Marking issue as new for engineering input. Thank you.

Comment 2

[Meron35]

Attachment: Screencast From 2025-09-15 18-52-05.mp4