1409033 - Cannot scroll using two fingers in Library window

Status: NEW

(Toolkit :: XUL Widgets, defect, P3)

Description

[Petruta Horea [:phorea]]

[Note]:
- This only reproduces on a specific Acer Aspire V5 laptop running Win 10 64-bit, with Intel Core i3-2377M, Synaptics PS/2 Port TouchPad Driver 19.1.3.6 and Touch support.

[Affected versions]:
- Firefox 56.0
- Firefox 57.0b8
- latest Nightly 58.0a1 2017-10-15

[Affected platforms]:
- Win 10 64-bit

[Steps to reproduce]:
1. Open Firefox with a clean profile
2. Create several History, Bookmarks and Downloads entries
3. Open the Library window and touch scroll using the fingers on the above categories

[Expected result]:
- Items can be scrolled

[Actual result]:
- https://bug1399126.bmoattachments.org/attachment.cgi?id=8918282
- Touch scrolling is not performed

[Regression range]:
- This is not a recent regression as it reproduces back to Firefox 52.0

[Additional notes]:
- Gecko profiler: https://perfht.ml/2yiM76S
- This may be a follow-up issue from bug 1345355

Comment 1

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

Probably this is happening because the library window is scrolled by JS code rather than APZ. Bug 1345355 fixed the APZ code path, but the various JS scrollers [1][2][3] all require a single touch input to scroll.

[1] http://searchfox.org/mozilla-central/rev/40b456626e2d0409b7034768b4d9526fc7235ea4/toolkit/content/widgets/listbox.xml#892
[2] http://searchfox.org/mozilla-central/rev/40b456626e2d0409b7034768b4d9526fc7235ea4/toolkit/content/widgets/scrollbox.xml#530
[3] http://searchfox.org/mozilla-central/rev/40b456626e2d0409b7034768b4d9526fc7235ea4/toolkit/content/widgets/tree.xml#709

Comment 2

[Firefox Bug Husbandry Bot]

https://wiki.mozilla.org/Bug_Triage/Projects/Bug_Handling/Bug_Husbandry#Update_affecteds

Comment 3

[Tim Guan-tin Chien [:timdream] (please needinfo)]

P3: Backlog.