1608352 - User is unable to reach the Facebook User and Password fields after exiting RDM

Status: VERIFIED FIXED

(DevTools :: Responsive Design Mode, defect, P2)

Description

[Rares Doghi, Desktop QA]

Attachment: 2020-01-10_10h34_54.mp4

[Affected versions]:
Nightly 74.0a1

[Affected platforms]:
Platforms: ALL

Steps :

1. Open the Firefox Browser.
2. Reach facebook.com.
3. Hit Ctrl+Shift+M in order to start RDM.
4. Select the iPad device or enable touch simulation.
5. Exit RDM mode.
6. Click the User or Password fields.

Expected Results :
The user should be able to click the fields.

Actual Results :
The User cannot enter the user or password fields, instead some text underneat the fields are highlighted.

Note : Please not that this issue only occurs on Facebook.com, this issue does not occur on Twitter or Reddit.
Please also note that this issue only occurs with devtools.responsive.metaViewport.enabled = true.
If the user Disables Touch Simulation before exiting RDM the issue does not occur.

Comment 1

[Patrick Brosset <:pbro>]

I couldn't reproduce the exact problem at first, but I think that's because I had the "reload on ..." options turned on in RDM.
With those on, I had a slightly different, but related, problem where I couldn't click inside of fields while inside RDM. Almost like if there was an offset between where I clicked and where the event actually happened.

I switched off the reload options and then could reproduce the issue described. And there too, it feels like its an offset problem after leaving RDM.
This could either be due to the viewport scaling logic somehow, or the way we simulate events.

Brad and/or Micah should investigate to know more.

Comment 2

[Micah [:mtigley] (she/her)]

I am also able to reproduce this issue with the steps provided above.

Interestingly, the issue seems to go away when I have devtools.responsive.browserUI.enabled = true. I'll keep investigating.

Comment 3

[Brad Werth [:bradwerth] (out until Aug 17)]

I'm narrowing it down a bit. In RDM, it's the transition off-to-on of touch simulation (meta viewport) that is the culprit. If you make this transition in RDM and reload or have auto-reload on, then the error is visible within RDM while the meta viewport is on. This shows up in the browser console:

TypeError: browsingContext.embedderElement.getTabBrowser is not a function SessionStore.jsm:2667:56

Which is at https://searchfox.org/mozilla-central/rev/ba4fab1cc2f1c9c4e07cdb71542b8d441707c577/browser/components/sessionstore/SessionStore.jsm#2667

So a quick fix may be to throw a try/catch block around that if block. That doesn't explain the bad behavior, but it may shield us from it. I'll try that.

Comment 4

[Brad Werth [:bradwerth] (out until Aug 17)]

Attachment: Bug 1608352: Wrap a call to getTabBrowser in a try/catch block.

Comment 5

[Brad Werth [:bradwerth] (out until Aug 17)]

This is a truly surprising regression -- Bug 1569475. Since the bug is a bit tricky to replicate, I'm not completely confident in it. I found the issue using mozregression and built a debug nightly with the patch reverted which did not seem to replicate the bug. I'm doing another regression now to triple-check.

If Bug 1569475 is the real cause, then this indicates that one of the callers to MVM::ClampZoom is doing a divide-by-zero, and that NaN value is causing further trouble down the line. If true, it's actually great to have a replication case for this odd calling pattern.

Comment 6

[Brad Werth [:bradwerth] (out until Aug 17)]

A second mozregression confirmed Bug 1569475.

Comment 7

[Brad Werth [:bradwerth] (out until Aug 17)]

Timing issues in debug make this very difficult for me to reproduce in a debug build. Specifically, the issue noted in Bug 1569626 always appears for me when trying to reproduce. I'm marking that bug as a blocker. It's possible they are related.

Comment 8

[Brad Werth [:bradwerth] (out until Aug 17)]

I can no longer reproduce this now that Bug 1569626 has landed. Is it still happening for you?

Comment 9

[Rares Doghi, Desktop QA]

Nope this issue no longer occurs in 74.0a1 (2020-01-21), when we exit RDM everything goes back to normal, but we did notice that while in RDM its hard to click inside the fields from the sign up form, while in iPad mode for instance we would have to click underneath the First name field in order to select it. Should we add a different issue for that ? is it already logged ?

Comment 10

[Brad Werth [:bradwerth] (out until Aug 17)]

(In reply to Rares Doghi from comment #9)

Nope this issue no longer occurs in 74.0a1 (2020-01-21), when we exit RDM everything goes back to normal, but we did notice that while in RDM its hard to click inside the fields from the sign up form, while in iPad mode for instance we would have to click underneath the First name field in order to select it. Should we add a different issue for that ? is it already logged ?

I don't have this other issue. Please file a bug with as specific a steps to reproduce as you can provide.

Comment 11

[Rares Doghi, Desktop QA]

I can no longer reproduce the issue on my side either, if it reoccurs ill add a different defect.

Comment 12

[Ryan VanderMeulen [:RyanVM]]

We know what fixed this, so FIXED is the correct resolution for this bug.

Comment 13

[Rares Doghi, Desktop QA]

This issue is Verified as fixed In our latest Beta 74.0b2 on Windows 10, Mac 10.14, and Ubuntu 18.04.