1478304 - Can't scroll when click/hover a sticky element in a parent with transform

Status: RESOLVED FIXED

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

Description

[Eternahl]

Attachment: sticky_scroll.html

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0
Build ID: 20180724223402

Steps to reproduce:

Try to scroll(mouse wheel) when hovering or clicking a sticky element

scroll container
└ css:transform:- element
   └ css:position:sticky element


Actual results:

Can't scroll


Expected results:

Can scroll

Comment 1

[roxleitan]

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0
Build ID: 20180726001822

I can reproduce the issue on Release 61.0.1, Beta 62.0b11 and latest Nightly 63.0a1(2018-07-26) on Windows 10 x64 and Mac OS X 10.12.

Comment 2

[Emilio Cobos Álvarez (:emilio)]

WFM with webrender, which means that this is likely a graphics bug instead.

Comment 3

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

Thanks for the testcase! This does seem like an APZ bug of some sort.

Comment 4

[Botond Ballo [:botond]]

What's happening here is:

  * Layout code calls Layer::SetFixedPositionData() for both fixed 
    and sticky layers. This is necessary because at least some of
    the fixed position data (the anchor and the sides) are used
    by AsyncCompositionManager for both fixed and sticky layers.

  * As a result, Layer::GetFixedPositionScrollContainerId() returns
    non-NULL_SCROLL_ID for both fixed and sticky layers.

  * When building the hit-testing tree, however, APZCTreeManager
    interprets Layer::GetFixedPositionScrollContainerId() returning
    non-NULL_SCROLL_ID as meaning the layer is fixed, and marks
    the corresponding hit-testing node as fixed, which in turn
    causes events that hit the node to be redirected to the
    document's RSF.

Comment 5

[Botond Ballo [:botond]]

Attachment: Bug 1478304 - Ensure Layer::GetFixedPositionScrollContainerId() returns NULL_SCROLL_ID for layers that are not fixed. r?kats

Comment 6

[Botond Ballo [:botond]]

Attachment: Bug 1478304 - Add a mochitest. r?kats

Depends on D9327

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ebf726d7d48d
Ensure Layer::GetFixedPositionScrollContainerId() returns NULL_SCROLL_ID for layers that are not fixed. r=kats
https://hg.mozilla.org/integration/autoland/rev/4a875561b1ae
Add a mochitest. r=kats

Comment 8

[Daniel Varga [:dvarga]]

https://hg.mozilla.org/mozilla-central/rev/ebf726d7d48d
https://hg.mozilla.org/mozilla-central/rev/4a875561b1ae