1802721 - White line at the bottom of Firefox content area when Windows taskbar auto-hides

Status: RESOLVED FIXED

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

Description

[luisgefe6]

Attachment: Screenshot (15).png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/109.0

Steps to reproduce:

have an app that fully hides your taskbar (i use my dock finder) and then have firefox maximized and then open windows explorer or any other map(it needs to be windowed) and than the white line appears

Actual results:

a white line appears when i open an app while firefox is full screen, i have tryed to open firefox in troubleshoot mode and the white line still appeared, so it definitely is a firefox bug and not a theme/extension error or windows or version or anything else

Expected results:

a white line shouldn't appear, firefox is the only app that the white line appears

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'WebExtensions::Untriaged' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Alex Cornestean]

Hello,

Since the issue still occurs in Troubleshoot Mode, which disables extensions and themes, it’s clear extensions are not involved.

I’ll change the Component and Product of the issue to better reflect the underlying causes. In case of error please revert the changes.

Thank you !

Comment 3

[luisgefe6]

i found something interesting, when i use a css skin that can utilize the MicaForEveryone app the white line becomes blurry and less noticeable
the used css theme is this one https://github.com/datguypiko/Firefox-Mod-Blur

Comment 4

[Simona Badau, Desktop QA]

I can only reproduce this issue when the Taskbar is hidden and the color set is light, but I reproduce it on other apps also - I tried using the latest Nightly 109.0a1 on Windows 10 x64.

Setting this to Core > Widget: Win32 so that our developers could take a closer look, if this is not the right component - please set it to a more appropriate one. Thanks!

Comment 5

[Ray Kraesig [:rkraesig]]

This may be closely related to bug 642851 — although, unlike that bug, it doesn't seem to require the taskbar to be on a nondefault side of the screen.

Comment 6

[Stephen A Pohl [:spohl]]

From duplicate bug 1819525 comment 1:

The Windows update that removed the one pixel line when hiding the taskbar was -
(KB5022913)

From duplicate bug 1819525 comment 2:

I should have added I am using Windows 11 Pro, 22H2.

Comment 8

[Chris Peterson [:cpeterson]]

I can reproduce this bug in both recent and two-year-old Firefox builds, so this is not a new Firefox bug. Unlike comment 4, I don't see the white line in other apps like Chrome or Edge.

My Windows color mode is "dark" and app color mode is "light".

Comment 9

[Alice0775 White]

I can also reproduce this on Chrome Windows10.

Comment 10

[spyda.bird]

I don't think this is a duplicate to Bug 1819525 -
With Win 11 update (KB5022913) from yesterday they removed the one pixel line that has been shown in Windows when hiding the task bar.
Firefox hasn'tt been updated to account for this.
That is why it appears in older versions of Firefox too if you have yesterdays update.
It only seems to affect Firefox people discuss it here -
https://www.reddit.com/r/Windows11/comments/11en8ej/ugly_taskbar_line_finally_gone_in_latest_update/

Comment 11

[spyda.bird]

I just uninstalled update (KB5022913) from yesterday and the white line is gone.
This is not a duplicate of bug 1819525 it is a new bug with similar symptoms.

Comment 12

[iharshraj1123]

Same issue.
I just updated windows yesterday and the while line came.

Comment 13

[zaheerdesai123]

Can confirm after updating windows 11, I am also getting this issue tried new profiles/safe mode and reinstalling but the issue is still present.

From a new profile.

Does anyone have any temporary fixes, maybe using css?

Comment 14

[iharshraj1123]

will this be addressed or we need to file a new bug?

Comment 15

[Alice0775 White]

About Windows11, See Bug 1819525.

Comment 16

[Ray Kraesig [:rkraesig]]

Bug 1819525 (and its root-cause bug, bug 642851) has been fixed in the latest Firefox Nightly. While this does appear to be a different bug, the fix for that happens to be general enough that it might deal with this one, too.

Can anyone experiencing this confirm whether or not it still occurs in the latest Nightly build?

Comment 17

[rockett1000]

It's not clear if you guys have done this setting already but it half solves the problem. There is still a bug with this setting that will allow the whiteline to come back:

1. Type "about:config" in the URL bar
2. Accept the prompt
3. Type "browser.fullscreen.autohide" and change the value from true to false

White bar will no longer appear when opening your browser, but resizing the window and then remaximizing it makes the white line reappear.

Making "browser.fullscreen.autohide" reapply after you maximise your browser window (just like it does when your open a fresh new firefox browser) sounds like the solution to the problem but I have 0 knowledge on how to implement that.

Comment 18

[spyda.bird]

(In reply to rockett1000 from comment #17)

It's not clear if you guys have done this setting already but it half solves the problem. There is still a bug with this setting that will allow the whiteline to come back:

1. Type "about:config" in the URL bar
2. Accept the prompt
3. Type "browser.fullscreen.autohide" and change the value from true to false

White bar will no longer appear when opening your browser, but resizing the window and then remaximizing it makes the white line reappear.

Making "browser.fullscreen.autohide" reapply after you maximise your browser window (just like it does when your open a fresh new firefox browser) sounds like the solution to the problem but I have 0 knowledge on how to implement that.

That only works when Firefox is fullscreen - And even without "browser.fullscreen.autohide" there is no line.
The bug relates to when Firefox is maximised.
Being in fullscreen is not a fix as you have to constantly exit fullscreen to use other applications i.e multitask.

Comment 19

[Ray Kraesig [:rkraesig]]

(In reply to rockett1000 from comment #17)

It's not clear if you guys have done this setting already but it half solves the problem. There is still a bug with this setting that will allow the whiteline to come back:

1. Type "about:config" in the URL bar
2. Accept the prompt
3. Type "browser.fullscreen.autohide" and change the value from true to false

This shouldn't have any effect on Firefox when it's merely maximized -- and I suspect it actually doesn't. On my system (the one I could repro bug 1819525 on, anyway), the initial color of the line was not necessarily white, even though it would reasonably consistently become white after a restore-maximize sequence; it was often far less noticeable. It's at least plausible that that's what you're seeing here.

Try this:

• Open Firefox initially maximized (such that you don't see the line).
• In that open Firefox window, go to data:text/html,<body bgcolor=magenta>.
• Take a fullscreen screenshot (Ctrl + Win + S).
• Paste that screenshot into an image editor. [Probably not MS Paint; see below.]
• Zoom in all the way and look at the bottom edge.

What I saw when I did that on my Windows 11 box (prior to the fix for 642851 being landed, which made this go away) was that the bottom line of pixels was not magenta, but was some much darker color.

(MS Paint didn't work for me because the bottom line of pixels was covered up by the horizontal scrollbar, even when zoomed in as far as it will let you go. I eventually worked around that but it was a five-step mess.)

Comment 20

[Asif Youssuff]

(In reply to Ray Kraesig [:rkraesig] from comment #16)

Bug 1819525 (and its root-cause bug, bug 642851) has been fixed in the latest Firefox Nightly. While this does appear to be a different bug, the fix for that happens to be general enough that it might deal with this one, too.

Can anyone experiencing this confirm whether or not it still occurs in the latest Nightly build?

Seems like we got confirmation here: https://www.reddit.com/r/firefox/comments/131r024/how_to_fix_white_line_on_bottom_of_screen/ji2vaub/

Comment 21

[Ray Kraesig [:rkraesig]]

(In reply to Asif Youssuff from comment #20)

Seems like we got confirmation here: https://www.reddit.com/r/firefox/comments/131r024/how_to_fix_white_line_on_bottom_of_screen/ji2vaub/

Good enough! Closing as RESOLVED FIXED.

@luisgefe6 (or anyone else), feel free to reopen if you still experience this issue in Firefox 114+ (whether a current Nightly build or the eventual Release version).