1983125 - Consider making delay for the sidebar's expand on hover feature customizable

Status: RESOLVED FIXED

(Firefox :: Sidebar, task)

Description

[Kelly Cochrane [:kcochrane]]

Currently, we've got a hardcoded delay of 200ms used for the delay when expand on hover is enabled for the sidebar. We should consider making this customizable via a pref in case users would like to adjust that to prevent accidental/unexpected expanding.

Comment 1

[Per Vognsen]

FWIW, the issues I'm seeing don't seem to be to related (or at least not in an obvious way, to me) to tweaking quantitative delays. I'll describe the specific use case that motivated the original request:

I'm on KDE Plasma on Linux. I have two monitors, each with a Firefox window. I'm using the vertical sidebar in auto-expand/contract mode. When I flick my mouse cursor as fast as I possible can from left to right across the monitor boundary, it always treats it as an expand-on-hover event. In other words, there doesn't seem to be any time sensitivity for the activation because the sidebar always comes up. Furthermore, I notice that the sidebar stays expanded even after the mouse cursor is out of the initial window, which is unexpected (and, with my programmer hat on, suggests some a few possible causes of the bug).

I should mention that this happens with just one Firefox window, but my motivating use case that was causing frustration was because I wanted to use two windows, which meant that I couldn't just switch left/bar attachment for the sidebar as a work-around for the bug/behavior since there's also going to be a separating vertical sidebar in both cases.

The screen recording also shows some other related glitchy behaviors. I couldn't get the screen recorder software to capture both screens, but suffice it to say that there's another monitor to the left of the shown monitor.

Comment 2

[Per Vognsen]

Attachment: Screencast_20250815_234102.webm

Screen recording referenced in previous comment.

Comment 3

[Per Vognsen]

(In reply to Per Vognsen from comment #1)

The screen recording also shows some other related glitchy behaviors. I couldn't get the screen recorder software to capture both screens, but suffice it to say that there's another monitor to the left of the shown monitor.

There doesn't seem to be any way to edit comments on Bugzilla, but I wanted to correct a typo so that it doesn't cause any confusion. The monitor recorded in the capture is the left monitor. The other, non-recorded monitor is to its right. So the mouse cursor is actually totally out of the recorded window/monitor when you see me flick the cursor right. (On further experimentation, the same kind of issue seems to happen with multiple windows on a single monitor, so the multi-monitor context might be a red herring though it was the motivating use case for me.)

Comment 4

[Kelly Cochrane [:kcochrane]]

Attachment: Bug 1983125 - Make delay for the sidebar's expand on hover feature a customizable pref

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/bf831dda4234
https://hg.mozilla.org/integration/autoland/rev/075ec0c2cda8
Make delay for the sidebar's expand on hover feature a customizable pref r=jsudiaman

Comment 6

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/075ec0c2cda8