1747792 - scrollbar with fullscreen youtube when changing fullzoom

Status: UNCONFIRMED

(Core :: Layout: Scrolling and Overflow, defect, P3)

Description

[na2007]

Attachment: forced_scroll_bar_in_ver95.0.2

Steps to reproduce:

I use a ‘Windows 7 Ultimate (64-bit)’ operating system with a 3840x2160 resolution, and the most important part is that the ‘Dot Per Inch (DPI)’ scaling is set to a custom 170% (it means 163 dots/inch).

Actual results:

According to my experience, the DPI change was not a problem in ‘Firefox’ until around version ‘90’, but after that, as it can be seen on the attached screenshot, the scrollbar was forced on the right and does not go away as it should in fullscreen mode (while watching a video on ‘YouTube’). It is important to note two facts: I use a 60% zoom (so minus 40%) on the ‘YouTube’ video pages, plus, due to the nature of the different video player, this persistent problem does not occur while watching a video also in fullscreen (with the same minus 40% zoom) on ‘Twitch.TV’.

Expected results:

I tested this situation the same way but without the DPI change, and there was no issue. The specific result was the following: I started zooming out on a ‘YouTube’ video page while watching the content in fullscreen mode, and the scrollbar immediately appeared on the right side — the more I zoomed out the larger it become. After refreshing the page, the new zoom-out view remained accordingly and the fullscreen mode hid the scrollbar, which mean the ‘YouTube’ video page noticed the change and scaled the fullscreen mode properly again. I think this is how it should normally operate, even with higher DPI setting than the regular 96 dots/inch (which is set as default by the ‘Windows 7’ operating system).

Comment 1

[Andrei Purice]

Hey na2007,
I'm not sure if this is an actual issue or expected behavior as changing the resolution and the zoom level triggers the appearance of a scroll bar.

Can you test the issue while in Safe Mode? You can find helpful info here : https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode .
Also a fresh new profile could help. You can find more about creating a new profile here : https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems#w_6-create-a-new-firefox-profile .
If possible, you can test this issue on the nightly build as well. Download the build from : https://www.mozilla.org/en-US/firefox/nightly/all/ .

Comment 2

[na2007]

(In reply to Andrei Purice from comment #1)

Hey na2007,
I'm not sure if this is an actual issue or expected behavior as changing the resolution and the zoom level triggers the appearance of a scroll bar.

Can you test the issue while in Safe Mode? You can find helpful info here : https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode .
Also a fresh new profile could help. You can find more about creating a new profile here : https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems#w_6-create-a-new-firefox-profile .
If possible, you can test this issue on the nightly build as well. Download the build from : https://www.mozilla.org/en-US/firefox/nightly/all/ .

I tested this further and the results were the same with the variables you mentioned. I think a very good solution would be a flag which could disable and re-enable the visual scrollbar for users who are affected by this phenomenon.

Comment 3

[Andrei Purice]

Setting a component for this issue in order to get the dev team involved.
If you feel it's an incorrect one please feel free to change it to a more appropriate one.

Comment 4

[Timothy Nikkel (:tnikkel)]

What is the steps to reproduce here exactly?

Play a youtube video in fullscreen, and without leaving full screen change the full zoom of the page (ctrl +/-)? And that creates a scrollbar on the full screen youtube content, but if you exit and re-enter full screen then the scrollbar doesn't appear even though you are still at the same full zoom?

Comment 5

[na2007]

(In reply to Timothy Nikkel (:tnikkel) from comment #4)

What is the steps to reproduce here exactly?

Play a youtube video in fullscreen, and without leaving full screen change the full zoom of the page (ctrl +/-)? And that creates a scrollbar on the full screen youtube content, but if you exit and re-enter full screen then the scrollbar doesn't appear even though you are still at the same full zoom?

Your description is correct, though there is one missing piece to the proper problem: setting the ‘Dot Per Inch (DPI)’ scaling to a higher value than ‘96’ on the mentioned operating system (in my case, it was custom 170% which means 163 dots/inch).

If you follow your instructions in the regular ‘96 DPI’ view, then what will happen with the scrollbar is exactly what you wrote (and what I described above in the ‘Expected results’ section). The problem only persists when a higher than ‘96 DPI’ value is set in the operating system — which affects the browser as intended. (Zooming out on the page can also be achieved by the ‘Ctrl + Mouse Wheel down’ combination.)

Comment 6

[Timothy Nikkel (:tnikkel)]

I can get a scrollbar to appear in Chrome as well, so seems more likely to be a site issue.

Comment 7

[Hiroyuki Ikezoe (:hiro)]

(In reply to na2007 from comment #0)

According to my experience, the DPI change was not a problem in ‘Firefox’ until around version ‘90’, but after that, as it can be seen on the attached screenshot, the scrollbar was forced on the right and does not go away as it should in fullscreen mode (while watching a video on ‘YouTube’).

Hey na2007, can you please try to use mozregression to narrow down which change caused this bug. The version number 90 makes me suspect this bug is another variant of bug 1757410 which regressed in 92.

Comment 8

[na2007]

Attachment: regression report

Comment 9

[na2007]

Attachment: proper website positioning

Comment 10

[na2007]

Attachment: proper fullscreen without scroll bar

Comment 11

[na2007]

(In reply to Hiroyuki Ikezoe (:hiro) from comment #7)

(In reply to na2007 from comment #0)

According to my experience, the DPI change was not a problem in ‘Firefox’ until around version ‘90’, but after that, as it can be seen on the attached screenshot, the scrollbar was forced on the right and does not go away as it should in fullscreen mode (while watching a video on ‘YouTube’).

Hey na2007, can you please try to use mozregression to narrow down which change caused this bug. The version number 90 makes me suspect this bug is another variant of bug 1757410 which regressed in 92.

Ikezoe-san, I used the regression tool to narrow the versions even further, and I uploaded 3 new files regarding this topic. I hope the regression report helps!

Comment 12

[Hiroyuki Ikezoe (:hiro)]

This is the regression range;
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=4d4bc56f77a199234c625dfdd85d06c62caae273&tochange=a96c49a026f646c041c781789de2b781b27cfe7c

Bug 1698783 is the only one suspicious in the list, but it makes me wonder that the reporter wants to make the scrollbar ignore DPI?