1247095 - Disable re-targeting mouse event in Fennec

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: General, defect)

Description

[Randall Barker [:rbarker]]

Re-targeting mouse events appears to cause these issues:

1) When an <a> or input element is above or below an element with a jQuery event handler, the function FindFrameTargetedByInputEvent is unable to detect that the jQuery enabled element is clickable due to the fact that the event handler is not actually stored on the element. This cause the <a> element to be targeted when it should not.

2) Selecting text above or below an <a> element is not possible because FindFrameTargetedByInputEvent will always re-target the element so the link pop-up menu is always displayed instead of selecting the text being longpressed.

Disabling re-targeting of mouse events in Fennec appears to be the best option at this time to alleviate these issues.

Comment 1

[Randall Barker [:rbarker]]

Attachment: 0001-Bug-1247095-Disable-re-targeting-mouse-event-in-Fennec-16020914-aff215c.patch

Comment 2

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

For (1), how does jQuery trigger the event handler?

Comment 3

[Randall Barker [:rbarker]]

(In reply to Kartikaya Gupta (email:[e-mail]) from comment #2)
> For (1), how does jQuery trigger the event handler?

It catchs the event at the top of the document, then uses the target in the event to look for an attribute called jquery12-really-big-number-38, the value of this attribute is the location of the elements jQuery cache entry. The various event handlers for the element are stored in the cache and are invoked from there.

Comment 4

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/3cb44e7f6639

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/3cb44e7f6639

Comment 6

[Randall Barker [:rbarker]]

Comment on attachment 8717647 [details] [diff] [review]
0001-Bug-1247095-Disable-re-targeting-mouse-event-in-Fennec-16020914-aff215c.patch

Approval Request Comment
[Feature/regressing bug #]:Bug 1233272, Bug 1235339
[User impact if declined]:Clicking on links and selecting text is much more difficult in certain situations. Particularly egregious on pages that use jQuery for for event handling.
[Describe test coverage new/current, TreeHerder]:There do not seem to be any tests that are specific to touch re-targeting. All tests pass with or without this feature disabled.
[Risks and why]: links with a very small touch area may become harder to press without zooming in.
[String/UUID change made/needed]:None

Comment 7

[Sylvestre Ledru [:Sylvestre]]

Comment on attachment 8717647 [details] [diff] [review]
0001-Bug-1247095-Disable-re-targeting-mouse-event-in-Fennec-16020914-aff215c.patch

OK, taking it as it seems to impact major websites
Should be in 45 beta 7

Comment 8

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/releases/mozilla-beta/rev/449003d52efb

Comment 9

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/releases/mozilla-aurora/rev/f9114bdcff3b

Comment 13

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

(In reply to Randall Barker [:rbarker] from comment #0)

1. When an <a> or input element is above or below an element with a jQuery
   event handler, the function FindFrameTargetedByInputEvent is unable to
   detect that the jQuery enabled element is clickable due to the fact that the
   event handler is not actually stored on the element. This cause the <a>
   element to be targeted when it should not.

There are no bugs linked to this one (or that I could find) that demonstrate this problem. I tried creating a test case manually but registering a click handler always added it as a listener on the individual element rather than on the root of the document. I tried with jQuery versions 3.4.1, 2.2.4, and 1.12.4 (the latest 3.x, 2.x, and 1.x versions available right now).

Comment 14

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

Attachment: My test page attempting to reproduce issue #1 from comment 0

Here's my simple test page that doesn't repro the problem.