1545393 - Remove layout.reflow.synthMouseMove

Status: RESOLVED FIXED

(Core :: DOM: UI Events & Focus Handling, enhancement)

Description

[Makoto Kato [:m_kato]]

bug 657844 adds layout.reflow.synthMouseMove prefs not to fire mouse move event by SynthesizeMouseMove for Fennec/Maemo.

Since Android can use native mouse event and device is more faster. So, I guess that we don't need this prefs.

Comment 1

[Makoto Kato [:m_kato]]

Attachment: Bug 1545393 - Remove layout.reflow.synthMouseMove setting from GeckoView

layout.reflow.synthMouseMove was added by Fennec/Maemo era (bug 657844) since this was low-end device. Since layout.reflow.synthMouseMove is false even if now, sampling rate of GeckoView's mouse event is still very sparse.

Since today is 2019, so we should change this to match sampling rate of mouse event with desktop.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0b8b9de44b8b
Remove layout.reflow.synthMouseMove setting from GeckoView r=geckoview-reviewers,agi

Comment 3

[Raul Gurzau (:RaulG)]

https://hg.mozilla.org/mozilla-central/rev/0b8b9de44b8b

Comment 4

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

Since the status are different for nightly and release, what's the status for beta?
For more information, please visit auto_nag documentation.

Comment 5

[Kartikaya Gupta (email:[e-mail])]

I think we should revisit if this is a good idea. The original reason for this pref may have been performance, but turning it on also produces unexpected UX effects. This is because Gecko has a notion of a "mouse" which is not visible to the user and in fact doesn't correspond to the user's mental model of what is happening on the page. This results in "random" seeming hover and mouseover effects like:

https://github.com/mozilla-mobile/fenix/issues/8779
https://github.com/mozilla-mobile/fenix/issues/9860
https://github.com/mozsearch/mozsearch/pull/308#issue-408060050

Are there any concrete advantages to turning on this pref? Maybe we can accomplish the same thing in a different way, or refine the implementation so that it doesn't produce these random-seeming effects.

Comment 6

[[ex-Mozilla] Agi Sferro | :agi]

Yeah it definitely sounds like we should roll this back. Makoto?

Comment 7

[Makoto Kato [:m_kato]]

(In reply to Agi Sferro | :agi | ⏰ PST | he/him from comment #6)

Yeah it definitely sounds like we should roll this back. Makoto?

I guess that random issue will occurs on Window Tablet. And this preferences is enabled by bug 1582363 again. It is OK to revert this preferences.
Kats, does github's issue occur on Windows tablet?

And random issue should file new bug for Core:Selection.

Comment 8

[Makoto Kato [:m_kato]]

or DOM:Events.

Comment 9

[Kartikaya Gupta (email:[e-mail])]

(In reply to Makoto Kato [:m_kato] from comment #7)

Kats, does github's issue occur on Windows tablet?

Yes, I see the issues occur on a Windows tablet too.

Comment 10

[Kartikaya Gupta (email:[e-mail])]

Filed bug 1633450 for the gecko-side changes needed. Filed bug 1633451 to turn the pref back off on Android for the moment.