1357904 - [e10s] dragging scrollbar with mouse scroll the page instead of the scrollable div

Status: RESOLVED DUPLICATE of bug 1357903

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

Description

[684sigma]

Attachment: issue with scrollbar, by reporter.htm

While testing bug 1357903, I noticed an issue on Nightly 55. It doesn't happen in Beta 53, Beta 52, ESR 45.
Sometimes dragging scrollbar doesn't work. Here's how to reproduce the bug:

1. Open attached page
2. Try to drag the small scrollbar down

Result: The page scrolls down
Expected: The <div> element should scroll down

Comment 1

[684sigma]

Mozregression-gui generated this regression range:
(in fact I only checked the last good and first bad builds in regression range from Bug 1355374)
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=4cbc57e29e25e8abe783b16915bd74325a040b02&tochange=d7518eef6b8924b4ddad6cdeeae4eed1c6129b26
->
1324117 – Enable APZ scrollbar dragging on Nightly
https://bugzilla.mozilla.org/show_bug.cgi?id=1324117

I see a slightly different result right after Bug 1324117: the first attempt to drag the scrollbar just fails (there's no result except scrollbar looking pressed), and the second attempt gives the exact result described in Comment #0. Probably related bug - Bug 1346632.

Comment 2

[ovidiu boca[:Ovidiu]]

I can reproduce this, I tested on Mac OS X 10.10 with FF Nightly 55.0a1(2017-04-19), if I turn off the apz.drag.enabled this issue is no longer reproducible.

Comment 3

[Alice0775 White]

"unaffected" on 53+?
Is it true?

I can reproduce the issue on Windows10 Nightly 55.0a1(2017-04-19).

Comment 4

[Timothy Nikkel (:tnikkel)]

If the pref apz.drag.enabled has to be true to see this then it is only enabled on nightly builds

https://dxr.mozilla.org/mozilla-central/rev/20dff607fb88ee69135a280bbb7f32df75a86237/modules/libpref/init/all.js#649

Comment 5

[ovidiu boca[:Ovidiu]]

The feature "Enable async scrolling via scrollbar dragging" it is only enabled on FF Nightly 55.0a1.

Comment 6

[Vincent Liu[:vliu]]

The apz.drag.enabled of my local ff-53 was default false. But when I turn it on, the issue still happens.

Comment 7

[Mike Taylor [:miketaylr]]

(marking as fix-optional for 55 since this is a nightly-only feature and blocks 1352312, which is the bug to ship by default)

Comment 8

[Botond Ballo [:botond]]

This almost certainly has the same root cause as bug 1357903: whatever is causing APZ to think it should be scrolling the page during wheel-scrolling, is also causing it to think it should be scrolling the page during scrollbar-dragging.

Comment 9

[Botond Ballo [:botond]]

(In reply to Botond Ballo [:botond] from comment #8)
> This almost certainly has the same root cause as bug 1357903: whatever is
> causing APZ to think it should be scrolling the page during wheel-scrolling,
> is also causing it to think it should be scrolling the page during
> scrollbar-dragging.

Setting bug 1357903 as a dependency for now. Once I verified that the fix for that fixes this too, I'll close this as a dupe.

Comment 10

[Botond Ballo [:botond]]

There's now a patch up for bug 1357903, and I've confirmed that it fixes this bug as well. Marking as dupe.