1411791 - In the past week or so, the taskbar hasn't been hiding as it should when Nightly or a video in NIghtly is fullscreen

Status: RESOLVED WORKSFORME

(Core :: Widget: Win32, defect, P3)

Description

[Jed]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0
Build ID: 20171025100449

Steps to reproduce:

Fullscreened Nightly or fullscreened a video, such as a YouTube or Twitch video. It doesn't happen in Edge. It does this on my laptop, but not on my PC.


Actual results:

The taskbar didn't hide and was overlayed on top of the video.


Expected results:

The taskbar should be hidden. Tried the override high DPI trick with properties.

Comment 1

[Panos Astithas (he/him) [:past] (please ni?)]

I can't reproduce this. Please try to reproduce the issue in safe mode:

https://support.mozilla.org/kb/troubleshoot-firefox-issues-using-safe-mode

It would also help if you could attach the contents of your about:support page.

Comment 2

[Jed]

Okay, that's very odd. I tried literally everything I could think of yesterday and today it's working fine. Maybe something in today's Nightly fixed it or it's just a weird bug.

Comment 3

[Jed]

Nevermind, it's doing it again.

Comment 4

[Emil Pasca [:emilpasca]]

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

I have tested this issue on Windows 10 x64 with the latest Firefox release (56.0.1) and the latest Nightly (58.0a1-20171029220112) and haven't managed to reproduce it.
After going to YouTube or Twitch and choosing the Fullscreen option for a video or using the "F11" key to fullscreen the browser the taskbar was correctly hidden.
I've also tested this with a High DPI and low DPI monitor, still unable to reproduce it.

Can you please try to reproduce the issue using safe mode as Panos mentioned in comment 1. If the issue is still reproducible please provide the information from about:support page.

Comment 5

[Jed]

It's still reproducible in safe mode, here's a copy from about:support: https://pastebin.mozilla.org/9071670

Okay, so I think Skype UWP is causing the issue as when I close the call control pop-up the taskbar vanishes as it should. The same issue happens in Chrome, but doesn't happen in Edge. Is it possible to fix this at all?

Comment 6

[Emil Pasca [:emilpasca]]

Can you please re-test this issue with the latest Firefox release and latest Nightly build?
Also if you think that the issue might be caused by Skype as mentioned in comment 5, I would suggest maybe re-installing or updating Skype.

Comment 7

[Jed]

(In reply to Emil Pasca [:emilpasca], Desktop Engineering QA from comment #6)
> Can you please re-test this issue with the latest Firefox release and latest
> Nightly build?
> Also if you think that the issue might be caused by Skype as mentioned in
> comment 5, I would suggest maybe re-installing or updating Skype.

It's been happening sporadically recently, without Skype UWP open. Sometimes just the cursor isn't hiding like it should and stays on top, and other times the taskbar shows.

Comment 8

[James Pole]

I'm running the latest Firefox release (71.0) on Win10/x64. I've noticed that sometimes, when I go to full screen mode in YouTube/Netflix, the taskbar will remain and overlap the video. This does not happen all the time. Sometimes I can make this behaviour go away by one or more of the following: switching to another window and switching back; clicking the start menu; mini/maximising Firefox; etc. I haven't yet found the exact sequence of events that triggers this issue nor the exact sequence of actions I need to undertake to fix/workaround this issue. It seems as though it happens randomly but I have a feeling there is some reason for this happening. I am at a bit of a loss as to what that reason might be but I am more than happy to provide any details that could help track down the issue.

Comment 9

[cyfare]

I can confirm this issue is occuring on both Windows 10 and 11. I maintain a custom compiled release product from upstream Nighly and my latest build has been facing this issue across all Windows devices: https://github.com/CYFARE/HellFire/issues/13

Hg pull and update date: 2025-03-06

Following is the mozconfig used:

# MOZCONFIG for "HellFire Lazer" Windows Build

# Build Configs
ac_add_options --enable-application=browser
ac_add_options --disable-artifact-builds

# Settings :: Optimizations
#ac_add_options MOZ_PGO=1
ac_add_options --enable-release
ac_add_options --disable-debug
ac_add_options --disable-debug-symbols
ac_add_options --disable-debug-js-modules
ac_add_options --disable-tests
ac_add_options --enable-strip
ac_add_options --enable-install-strip
ac_add_options --enable-clang-plugin
ac_add_options --enable-wasm-avx
ac_add_options --enable-rust-simd
ac_add_options --disable-parental-controls
ac_add_options --disable-crashreporter
ac_add_options --disable-updater
ac_add_options --disable-maintenance-service
ac_add_options --disable-bits-download
ac_add_options --disable-update-agent
ac_add_options --enable-jemalloc

ac_add_options --enable-raw
ac_add_options --enable-webrtc
ac_add_options --enable-jxl
ac_add_options --enable-av1
ac_add_options --enable-eme=widevine

ac_add_options --enable-hardening
ac_add_options --enable-sandbox

mk_add_options MOZ_PARALLEL_COMPILE=16
mk_add_options MOZ_PARALLEL_BUILD=16
mk_add_options MOZ_CRASHREPORTER=0
mk_add_options MOZ_DATA_REPORTING=0
mk_add_options MOZ_SERVICES_HEALTHREPORT=0
mk_add_options MOZ_TELEMETRY_REPORTING=0

export RUSTFLAGS="-C opt-level=3 -C target-cpu=x86-64-v3 -C codegen-units=1 -Cpanic=abort -Cforce-frame-pointers=no -Cllvm-args=--inline-threshold=1000 -Cllvm-args=-vectorize-loops -Cllvm-args=-vectorize-slp"
export CFLAGS="-O3 -march=x86-64-v3 -mavx2 -maes -msse4.2 -fno-semantic-interposition -fomit-frame-pointer -fdata-sections -ffunction-sections -fno-plt -funroll-loops $CFLAGS"
export CXXFLAGS="$CFLAGS"
export LDFLAGS="-Wl,-O3 -Wl,--gc-sections -Wl,-z,now -Wl,-z,relro -Wl,--icf=all $LDFLAGS"

# Compile Configs
mk_add_options AUTOCLOBBER=1
mk_add_options MOZ_MAKE_FLAGS="-j16"
mk_add_options MOZ_OBJDIR=@TOPSRCDIR@/objdir-opt

Apart from the taskbar, I also notice that if any youtube link is directly pasted after starting the browser (not visited via clicking the video link), then when the fullscreen button on video controls is pressed immediately before the video starts playing, video player is not set to fullscreen, but the youtube application (rest of the site) becomes fullscreen. In this issue, the taskbar bug also persists.

Comment 10

[cyfare]

For reference, this is exactly the same as this user report: https://connect.mozilla.org/t5/discussions/going-fullscreen-in-youtube-or-netflix-doesn-t-hide-the-taskbar/td-p/89248

Comment 11

[cyfare]

Issue is solved by implementing these about:config changes:

https://github.com/CYFARE/HellFire/issues/13#issuecomment-2707915761

Comment 12

[David Parks [:handyman]]

Thanks, cyfare, that is a huge help. Can you still reproduce the issue if the prefs aren't changed? I can't reproduce it at all but I have a potential fix I'd like you to try, if you can still reproduce this.

Direct link to build: zip or installer exe
(Here is a link to the build job with the patches)

---

The link in comment 11 disables the FullscreenTransitionTask, which animates the fade-out/fade-in. The prefs to do this are:

• Set full-screen-api.transition-duration.enter and full-screen-api.transition-duration.leave to 0 0
• Set full-screen-api.warning.timeout to 0

I cannot get the taskbar to appear over YouTube videos in fullscreen, although I don't know if there is more steps to reproduce than to play a video fullscreen.

In bug 1952284 comment 9, rkraesig changed some full screen behavior to fix a similar browser issue that appeared in Windows recently. cyfare mentions there that this didn't fix the issue. The try build above adds the MarkAsHidingTaskbar behavior to the fullscreen transition window -- it was formerly only on the browser window. This is just a theory atm.

Apart from the taskbar, I also notice that if any youtube link is directly pasted after starting the browser (not visited via clicking the video link), then when the fullscreen button on video controls is pressed immediately before the video starts playing, video player is not set to fullscreen, but the youtube application (rest of the site) becomes fullscreen. In this issue, the taskbar bug also persists.

This I can reproduce, by running a debug build. It seems to be timing related -- maybe there is a race involved in the completion of the full screen transition and the element going fullscreen.

Comment 13

[cyfare]

(In reply to David Parks [:handyman] from comment #12)

Thanks, cyfare, that is a huge help. Can you still reproduce the issue if the prefs aren't changed? I can't reproduce it at all but I have a potential fix I'd like you to try, if you can still reproduce this.

Direct link to build: zip or installer exe
(Here is a link to the build job with the patches)

---

The link in comment 11 disables the FullscreenTransitionTask, which animates the fade-out/fade-in. The prefs to do this are:

• Set full-screen-api.transition-duration.enter and full-screen-api.transition-duration.leave to 0 0
• Set full-screen-api.warning.timeout to 0

I cannot get the taskbar to appear over YouTube videos in fullscreen, although I don't know if there is more steps to reproduce than to play a video fullscreen.

In bug 1952284 comment 9, rkraesig changed some full screen behavior to fix a similar browser issue that appeared in Windows recently. cyfare mentions there that this didn't fix the issue. The try build above adds the MarkAsHidingTaskbar behavior to the fullscreen transition window -- it was formerly only on the browser window. This is just a theory atm.

Apart from the taskbar, I also notice that if any youtube link is directly pasted after starting the browser (not visited via clicking the video link), then when the fullscreen button on video controls is pressed immediately before the video starts playing, video player is not set to fullscreen, but the youtube application (rest of the site) becomes fullscreen. In this issue, the taskbar bug also persists.

This I can reproduce, by running a debug build. It seems to be timing related -- maybe there is a race involved in the completion of the full screen transition and the element going fullscreen.

Installed latest Nightly version from https://www.mozilla.org/firefox/channel/desktop/?utm_source=blog.nightly.mozilla.org&utm_medium=referral&utm_campaign=blog-nav#nightly (Windows) on fresh Win11 system and issue no longer exists. But the about:config settings mentioned above are unchanged. I'm curious what causes this, but well.. we've a mitigation atleast..

Comment 14

[David Parks [:handyman]]

(In reply to cyfare from comment #13)

Installed latest Nightly version from https://www.mozilla.org/firefox/channel/desktop/?utm_source=blog.nightly.mozilla.org&utm_medium=referral&utm_campaign=blog-nav#nightly (Windows) on fresh Win11 system and issue no longer exists. But the about:config settings mentioned above are unchanged. I'm curious what causes this, but well.. we've a mitigation atleast..

I take this to mean that the bug is gone in the latest nightly -- and pref changes and other mitigations are no longer needed. I had personally seen different taskbar issues with a number of applications around the time these reappeared a few weeks ago and they seem to have gone away. This may have been due to an OS update.