1302737 - [e10s] Cannot touch scroll multiple tabs

Status: VERIFIED FIXED

(Toolkit :: UI Widgets, defect)

Description

[Petruta Horea [:phorea], Desktop QA]

[Note]:
- Create 'browser.tabs.remote.force-enable' preference and set it to true. Restart the browser.

[Affected versions]:
- Nightly 51.0a1 2016-09-14

[Affected platforms]:
- Microsoft Surface Pro 2 with Win 10 64-bit

[Steps to reproduce]:
1. Open multiple tabs so that the tab bar can be scrolled 
2. Touch scroll the tabs
3. Tap "X" to close a tab

[Expected result]:
2. The tabs can be scrolled
3. The tabs are rearranged after closing one of them

[Actual result]:
2. The tabs cannot be scrolled
3. An empty space remains on the right side of Tab Bar.

Comment 1

[Markus Stange [:mstange]]

The tab bar is a <scrollbox> which process wheel events to do scrolling. Fixing this may require adding touch event listeners to scrollbox.xml.

Comment 2

[Dão Gottwald [:dao]]

(In reply to Markus Stange [:mstange] from comment #1)
> The tab bar is a <scrollbox> which process wheel events to do scrolling.
> Fixing this may require adding touch event listeners to scrollbox.xml.

Why would this only manifest with e10s though? Sounds like a core :: event handling bug to me.

Comment 3

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

We only fire touch events when e10s is enabled. Without e10s we don't have the machinery to properly support touch events and they get converted to mouse events instead.

Comment 4

[Markus Stange [:mstange]]

How does touch scrolling work with those simulated mouse events? Do we synthesize wheel events?

Comment 5

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

With e10s disabled you mean? Yeah, there's some goop in nsWinGesture.cpp that gets gesture events from Windows (as opposed to WM_TOUCH messages) and dispatches it as wheel events.

Comment 6

[Markus Stange [:mstange]]

Ah, interesting.

Comment 7

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

Working on this. I have a patch that makes the scrolling work already, but I want to fix the "empty space left on the side of the tab bar after closing a bunch of tabs" as well. That code appears to be somewhere other than scrollbox.xml

Comment 8

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

Attachment: Bug 1302737 - Add rudimentary touch-scrolling support to the XUL scrollbox widget.

Review commit: https://reviewboard.mozilla.org/r/81454/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/81454/

Comment 9

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

Attachment: Bug 1302737 - When closing tabs with non-mouse devices (e.g. touch, pen), don't enter locked-tab-size mode.

The problem with entering this mode with touch input is that there's no obvious
time to exit the mode. If the user taps on the tab-close button and then lifts
their finger, they might want to close more tabs or they might want to do
something else. For touch/pen, we don't get events like mousemove/mouseout
to distinguish between the two cases. Using a timeout is one possibility but
for now it seems safer to simply not enter that mode when the user is using
touch input to close tabs.

Review commit: https://reviewboard.mozilla.org/r/81456/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/81456/

Comment 10

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

The try push at https://treeherder.mozilla.org/#/jobs?repo=try&revision=3067b29ef288&group_state=expanded includes the first patch on this bug.

Comment 11

[:Gijs (he/him)]

Comment on attachment 8795399 [details]
Bug 1302737 - When closing tabs with non-mouse devices (e.g. touch, pen), don't enter locked-tab-size mode.

https://reviewboard.mozilla.org/r/81456/#review80028

Comment 12

[Dão Gottwald [:dao]]

Comment on attachment 8795398 [details]
Bug 1302737 - Add rudimentary touch-scrolling support to the XUL scrollbox widget.

see bug 1302736 comment 11

Comment 13

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/4d39febef604
Add rudimentary touch-scrolling support to the XUL scrollbox widget. r=dao
https://hg.mozilla.org/integration/mozilla-inbound/rev/f2bac20c2f76
When closing tabs with non-mouse devices (e.g. touch, pen), don't enter locked-tab-size mode. r=Gijs

Comment 14

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/4d39febef604
https://hg.mozilla.org/mozilla-central/rev/f2bac20c2f76

Comment 15

[Petruta Horea [:phorea], Desktop QA]

Verified as fixed with 50.0a1 Nightly 2016-10-18.