1436474 - double click on HTML5 player (for fullscreen) unreliable on multi-monitor setup

Status: RESOLVED DUPLICATE of bug 1129227

(Core :: DOM: UI Events & Focus Handling, enhancement, P3)

Description

[Dan]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0
Build ID: 20180128191252

Steps to reproduce:

When having firefox on 2nd window (not Windows 10 mainscree), it acts unreliable on double click to fullscreen a twitch livestream (some. Pressing F5 (refresh website) solves the problem everytime.


Actual results:

Nothing


Expected results:

Livestream going to fullscreen sometimes, sometimes not...

Comment 1

[Dan]

Note: the UI shows the icon for "is in fullscreen mode now" when double clicking... very weird.

Comment 2

[Dan]

Please confirm this bug asap, guys...

Comment 3

[roxleitan]

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0
Build ID:20180207220120

Managed to reproduce this issue using Firefox 58.0.1(Build ID: 20180128191252), Firefox Beta 59.0b7 and Nightly 60.0a1 (2018-02-07)on Windows 10 x64.

Comment 4

[roxleitan]

Attachment: full screen button.png

Comment 5

[Dan]

Any ETA for a fix in Nightly (60) ? (this week if possible?)

Comment 6

[Dan]

Should I change tracking from FF 58 to 60 (as bug is in FF 60 too) ?

Comment 7

[roxleitan]

Andrew, what do you think?

Comment 8

[Dan]

Should we put a needinfo for Andrew here or will he most probably read this bugreport today anyways?

Comment 9

[Andrew Overholt [:overholt]]

Xidorn knows a lot about fullscreen stuff.

It would be nice to have a clear STR with URLs just to be sure we're all talking about the same thing.

Comment 10

[Dan]

What does STR stand for? (sry I'm not a professional in bugzilla)

Comment 11

[Dan]

Working for me currently, tried a lot to reproduce, not reproducable at the moment for me anymore (maybe www.twitch.tv fixed the problem? Or was it Windows 10 problem?). I will keep an eye on this bug the next days.

Comment 12

[Dan]

@Andrew, you can/could visit any video on any twitch channel to reproduce the issue, but it's working at the moment for me.

Comment 13

[roxleitan]

I cannot reproduce the issue on the latest Nightly 60.0a1 (Build ID:20180227100126), Firefox Release 58.0.2 and Firefox Beta 59.0b12 (Build ID:20180222170353) on Windows 10 x64.
Based on my results and reporter's comment 11 I will close this bug Resolved-WORKSFORME.

If anyone can still reproduce it on latest versions, feel free to reopen the issue and provide more information.

Comment 14

[Dan]

Thanks for your help, Roxana and Andrew! ;)

Comment 15

[Dan]

Yep still happening. Have to try to find the reproductive steps though...

Comment 16

[Dan]

YES found another bug that is probably causing it, when double-clicking into a stream windows like 10 times or so, (fullscreen, windowed, etc etc back and forth) the whole UI disappears... (should I make a new bug-report?)

Comment 17

[Dan]

I think I found the issue! Some Twitch streams use the Extension called "overlay by Muxy" in their streams, which is causing the fullscreen double-click to get bugged (even when enabling "double-click for fullscreen" in Muxy's overlay, only the icon changes, window not going fullscreen thoug. Tested with this 24/7 stream: https://www.twitch.tv/monstercat
Roxana, Xidorn or Andrew, can you confirm this? (in the stream, right side there are 2 icons in the stream window, 1 of the 2 symbols is a dragon where you can enable "double-click to fullscreen", when enabled, even doubleclick won't do fullscreen. Please press 10 times or so into stream to try to reproduce). Thank you guys!

Comment 18

[Andrew Overholt [:overholt]]

(In reply to Daniel from comment #17)
> I think I found the issue! Some Twitch streams use the Extension called
> "overlay by Muxy" in their streams, which is causing the fullscreen
> double-click to get bugged (even when enabling "double-click for fullscreen"
> in Muxy's overlay, only the icon changes, window not going fullscreen thoug.
> Tested with this 24/7 stream: https://www.twitch.tv/monstercat
> Roxana, Xidorn or Andrew, can you confirm this? (in the stream, right side
> there are 2 icons in the stream window, 1 of the 2 symbols is a dragon where
> you can enable "double-click to fullscreen", when enabled, even doubleclick
> won't do fullscreen. Please press 10 times or so into stream to try to
> reproduce). Thank you guys!

I can confirm. The console shows some stuff:

Request for fullscreen was denied because Element.requestFullscreen() was not called from inside a short running user-generated event handler.
player.js:28:2878
ReferenceError: event is not defined[Learn More]
viewer.js:18:58290
ReferenceError: event is not defined[Learn More]
viewer.js:18:58290
ReferenceError: event is not defined[Learn More]
viewer.js:18:58290
ReferenceError: event is not defined[Learn More]
viewer.js:18:58290
ReferenceError: event is not defined[Learn More]
viewer.js:18:58290
ReferenceError: event is not defined[Learn More]
viewer.js:18:58290
ReferenceError: event is not defined[Learn More]
viewer.js:18:58290
ReferenceError: event is not defined[Learn More]
viewer.js:18:58290
ReferenceError: event is not defined[Learn More]
viewer.js:18:58290

Comment 19

[Dan]

So is a fix possible very soon in Nightly?

Comment 20

[Dan]

This is a REALLY frustrating issue and affects probably more than thousands of Firefox users (everyone who views streams on Twitch) and should be P1 priority... (it is not an issue in Google Chrome and now hundreds of Twitch viewers will switch to Chrome because this bug is not occuring in Chrome for some reason)

Comment 21

[Dan]

Ok I can confirm issue also happens in ESR 52.6.0.

Comment 22

[Dan]

What does "Trunk" mean on FF 60 ?

Comment 23

[Dan]

Issue seems fixed at least in FF 60 on notebook (single screen), will test home again too on multi-monitor setup.

Comment 24

[Dan]

sorry meant 61.0

Comment 25

[Dan]

Yeeeepp.. issue STILL persisting on FF 61 with multi monitor!!

Comment 26

[Xidorn Quan [:xidorn] UTC+10]

I... cannot reproduce this with the url in comment 17, even after logging in.

From what Andrew observed in comment 18, it could possibly be an issue in the website which is requesting fullscreen from somewhere it is not allowed currently.

If it works in other browsers, they may have a different way for tracking connection between user gesture (e.g. click / keypress) and fullscreen request than Firefox.

I think the easiest general solution to this kind of issue is what I mentioned in bug 1185052 comment 3, but security people haven't replied yet whether they think that is okay :/

Comment 27

[Xidorn Quan [:xidorn] UTC+10]

If the observation in comment 18 is indeed where the issue is, then it should effectively be the same issue as bug 1129227.

Comment 28

[Dan]

So it means this bug can only be fixed if bug 1129227 gets fixed?

Comment 29

[Xidorn Quan [:xidorn] UTC+10]

We can also make this a Tech Evangelism bug and contact the website to fix.

That being said, it is unclear to me how this can be related to multi-monitor setup at all. I don't expect the issue to be affected by whether there is multi-monitor at all, so what you are experiencing may or may not be the same issue observed in comment 18.

Comment 30

[Dan]

I don't know how bad it is when "Element.requestFullscreen()" is not called from inside a short running user-generated event handler... But Google has it working in Chrome browser, so it should be possible to fix in Firefox I hoped, but yes, Twch Evangelism bug and contact the website to fix might be a good way to fix too.

Comment 31

[Xidorn Quan [:xidorn] UTC+10]

Fullscreen is a dangerous feature that we always want user to be aware of that they are triggering it via only allowing it in certain case, e.g. when user click something etc. because otherwise a web app may be able to spoof anything via requesting fullscreen quietly somehow.

This is a security requirement for Fullscreen API, and all browsers deploy this kind of restrictions in some way, and it's also required by the spec.

It is possible that different browsers use different approaches to enforce this restriction, and that may end up having different behavior if a website doesn't meet the requirement of the strictest one.

We may want to choose a weaker way to apply this restriction to have better webcompat and developer experience, but that needs approval from security, since this whole restriction is there for security reason.

Comment 32

[Dan]

Ok thanks for your reply. can we have a developer from the security team read this bug thread please and reply here?

Comment 33

[Dan]

Andrew where in Firefox Nightly source code so I find "Element.requestFullscreen()", "player.js" and "viewer.js" ? I hope I can fix this bug myself then.

Comment 34

[Andrew Overholt [:overholt]]

Wennie can probably find someone to chime in from a security standpoint.

Xidorn is in a much better position than I am to answer comment 33 so I'll his needinfo for that :)

Comment 35

[Xidorn Quan [:xidorn] UTC+10]

player.js and viewer.js are code of the website, not in Firefox.

requestFullscreen is defined inside Firefox from https://searchfox.org/mozilla-central/rev/49cc27555d5b7ed2eb06baf156693dd578daa06f/dom/base/Element.cpp#3567-3586

Comment 36

[Firefox Bug Husbandry Bot]

See bug 1547409. Moving webcompat whiteboard tags to project flags.