Scaling one monitor (to 1.5x in my case) can cause Firefox to lose window features (titlebar, buttons, bookmark bar)

[Allan Bogh]

One monitor is a 4K monitor scaled to 1.5x, the other is a normal 1920x1080 monitor scaled to 1x.

While Firefox is already open, after logging in with the lock screen, or modifying display settings, sometimes Firefox will lose the titlebar, address bar, buttons, and bookmark bar. The website being displayed will still show, however not all features are usable (right click menu, mouse icon doesn't change).

Reproduction steps:

- Change zoom level of one or more monitors to >1.0 but less than 2.0 (have not tested with non-fractional zooms)
- Open Firefox and browse to any website
- Lock screen or leave computer alone until the screen locks.
- Login
- Firefox may have lost the window chrome

Workaround:

- Open Display Settings
- Change display settings or zoom level, then change back.

Computer info:

- Ubuntu 20.04.1
- Fractional Scaling enabled
- NVidia GeForce GTX 1080/PCIe/SSE2
- Gnome 3.36.3
- X11
- Samsung LU32J590 4K (3840x2160) @ 1.5x
- Dell E2416Hb 1920x1080 rotated portrait left, right of Samsung

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xorg 1:7.7+19ubuntu14
ProcVersionSignature: Ubuntu 5.4.0-52.57-generic 5.4.65
Uname: Linux 5.4.0-52-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
.proc.driver.nvidia.gpus.0000.02.00.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0000:02:00.0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.suspend: suspend hibernate resume
.proc.driver.nvidia.suspend_depth: default modeset uvm
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 435.21 Sun Aug 25 08:17:57 CDT 2019
 GCC version: gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)
ApportVersion: 2.20.11-0ubuntu27.10
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CasperMD5CheckResult: skip
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Wed Nov 4 09:31:17 2020
DistUpgraded: 2020-04-03 12:51:44,815 DEBUG Running PostInstallScript: './xorg_fix_proprietary.py'
DistroCodename: focal
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 NVIDIA Corporation GP104 [GeForce GTX 1080] [10de:1b80] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: eVga.com. Corp. GP104 [GeForce GTX 1080] [3842:6188]
InstallationDate: Installed on 2018-04-28 (920 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-52-generic root=UUID=dfb5d6fd-4a4e-471d-bb00-77a6729533d8 ro quiet splash pci=nommconf vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to focal on 2020-04-03 (214 days ago)
dmi.bios.date: 04/06/2018
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: P3.80
dmi.board.name: X99 Extreme4
dmi.board.vendor: ASRock
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP3.80:bd04/06/2018:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnX99Extreme4:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.family: To Be Filled By O.E.M.
dmi.product.name: To Be Filled By O.E.M.
dmi.product.sku: To Be Filled By O.E.M.
dmi.product.version: To Be Filled By O.E.M.
dmi.sys.vendor: To Be Filled By O.E.M.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.101-2
version.libgl1-mesa-dri: libgl1-mesa-dri 20.0.8-0ubuntu1~20.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx 20.0.8-0ubuntu1~20.04.1
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.8-2ubuntu2.4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200226-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1

[Allan Bogh (ajbogh)]

I've attached an image of Netflix showing on the Dell monitor after I changed the zoom level back to 1.5x for the Samsung monitor. The image shows Firefox without the window border. Netflix was not in fullscreen mode.

[Daniel van Vugt (vanvugt)]

If the problem is just the window decorations then this is an Xwayland bug (source package 'xorg-server').

But I can't tell right now if parts of Firefox itself are also missing. And either way, the problem could be triggered by Firefox itself.

[Allan Bogh (ajbogh)]

@vanvugt Can you describe which parts of Firefox you can't tell are missing? I can update the information if necessary.

Regarding which parts are missing here's a list:

- titlebar/tabs
- minimize, maximize, close buttons
- Back/forward/refresh/home buttons, address bar, add-on buttons, settings hamburger menu
- Bookmark bar
- Scrollbar

Navigation with escape button works.

Mouse works.

Scrolling with mouse works.

Initial right-click of the mouse shows the context menu offset from the mouse (showed up on Primary display instead of Secondary where the mouse was clicked). Other right clicks of the mouse show the context menu in the correct place.

The dev console shows with all of the buttons and options present.

Other applications in windowed or fullscreen mode display on the monitor in the correct resolution and with the window chrome.

[Allan Bogh (ajbogh)]

Here's another image with the windows showing in alt-tab mode (whatever that's called - pressed Super button once).

[Daniel van Vugt (vanvugt)]

Thanks. It looks like your Firefox is configured to use client-side decorations. That makes this a pure Firefox bug since it would be responsible for rendering everything.

[Olivier Tilloy (osomon)]

Thank you for the report Allan. Would you mind filing an upstream bug at https://bugzilla.mozilla.org/enter_bug.cgi#h=dupes%7CFirefox, and sharing the link to it here?
Thanks!