1187439 - [e10s] Scroll inertia not working in Multiprocess

Status: RESOLVED WORKSFORME

(Core :: Widget: Win32, defect)

Description

[alex]

Attachment: VID_20150724_122818.webm

User Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:42.0) Gecko/20100101 Firefox/42.0
Build ID: 20150724030210

Steps to reproduce:

Enable multiprocess in nightly, attempt to flick scroll on a touchscreen.


Actual results:

The page scrolls, but there is no inertia like there is without multiprocess enabled.


Expected results:

Expected behaviour should be no different from scrolling with multiprocess disabled.

Comment 1

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

This is a legit e10s regression - there is windows widget nsWinGesture code that handles touch scrolling if APZ touch scrolling is not enabled. And with that code the inertia in scrolling is broken when e10s is enabled (regardless of APZ on or off).

The good news is that setting dom.w3c_touch_events.enabled=2 will stop using the nsWinGesture code and switch to APZ touch scrolling, which has inertia and is much smoother. So whether or not we ship this regression depends on whether or not we ship e10s before APZ touch scrolling is baked (see bug 1180706).

Comment 2

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

Just an addendum to comment 1 (thanks Jim for reminding me): touch hardware on Windows triggers accessibility which causes e10s to be disabled, so the e10s regression is not really a thing we need to worry about because it doesn't happen in the default configuration.