UI scaling broken after last update in Xenial

[Andre Brait]

After an update that went live a few days ago, Unity's fractional scaling is misbehaving for some scaling values.

It's something I had already noticed in Unity that shipped in Zesty some time ago. With this update, this now affects Xenial as well.

For scaling values up to 1.38x it behaves as it should, but when the scaling hits the 1.5x mark, the UI elements resize as though I had selected a much higher scaling. Text resizes to 1.5x, but the UI itself scales to a much higher number.

It wasn't like that until this last round of updates to Xenial.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: unity 7.4.5+16.04.20171201.3
ProcVersionSignature: Ubuntu 4.13.0-32.35~16.04.1-generic 4.13.13
Uname: Linux 4.13.0-32-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.1-0ubuntu2.15
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Sun Feb 18 15:08:20 2018
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
DkmsStatus:
 bbswitch, 0.8, 4.13.0-32-generic, x86_64: installed
 bbswitch, 0.8, 4.4.0-112-generic, x86_64: installed
 nvidia-384, 384.111, 4.13.0-32-generic, x86_64: installed
 nvidia-384, 384.111, 4.4.0-112-generic, x86_64: installed
GraphicsCard:
 Intel Corporation Device [8086:5916] (rev 02) (prog-if 00 [VGA controller])
   Subsystem: Dell Device [1028:0781]
InstallationDate: Installed on 2017-07-28 (205 days ago)
InstallationMedia: Ubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.2)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 004: ID 0cf3:e007 Atheros Communications, Inc.
 Bus 001 Device 003: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card Reader Controller
 Bus 001 Device 002: ID 0bda:5769 Realtek Semiconductor Corp.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. Inspiron 7460
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.13.0-32-generic root=/dev/mapper/ubuntu--vg-root ro quiet splash vt.handoff=7
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/13/2017
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.4.2
dmi.board.name: 0V736W
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.4.2:bd12/13/2017:svnDellInc.:pnInspiron7460:pvr:rvnDellInc.:rn0V736W:rvrA01:cvnDellInc.:ct10:cvr:
dmi.product.family: Inspiron
dmi.product.name: Inspiron 7460
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.12.3+16.04.20171116-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.83-1~16.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 17.2.8-0ubuntu0~16.04.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 17.2.8-0ubuntu0~16.04.1
version.xserver-xorg-core: xserver-xorg-core N/A
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A

[Andre Brait (andrebrait)]

Adding two screenshots highlighting the issue.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Tobias Quinn (tobias-quinn)]

I can confirm that this also broke on my system where I have scaling set to 1.62

[plum (plumerlis)]

confirmed
set to 1.5 will make my UI to 2X
too big for WQHD screen

[Peter Newcomb (peter-petesbox)]

In my case, the update broke scaling of window and menu contents but not title and menu bars, and it made the window and menu contents appear smaller at 1.5 than at 1.38, while the title and menu bars continue to appear larger. The problem manifests with scaling >= 1.5, but also appears to have some interesting behavior between 2.38 and 2.5, kind of like there's some kind of truncation/quantization that's phase-shifted by 0.5. Basically window and menu contents at 2.38 appear to be the same size as they are at 1.38, and same for 2.5 and 1.5.

[fletch (richard-artumi)]

In my case I have 2 displays one at 1920x1080 (Display A) and another at 3840x2160 (Display B). When I have (A) and (B) active or just (A) active, zoom behaves normally at <=1.38 but at >=1.5 it goes much larger than it should. When only (B) is active, then the behaviour of the zoom at <=1.38 is different, it is far too. small.

[Steve Kevin (gjzh666-gr)]

In my case, the newest update (unity 7.4.5+16.04.20171201.3) broke scaling levels larger than 1.38; when scale for menu and title bars is set as values larger or equal to 1.5 in Displays setting, window text displays *way* smaller than it is set as 1.38.

[macat (attila-maczak)]

This has been a really annoying bug for me. I was trying to downgrade the package without much success. Is it possible to figure out when a bugfix lands in the repo?

[plum (plumerlis)]

You can downgrade your Unity and Compiz to older version
this may help
https://askubuntu.com/questions/59443/how-can-i-revert-back-from-an-upgrade-to-the-proposed-repository

and don't forget to hold your unity version

sudo apt-mark hold unity

then you can upgrade to newest again(except unity and compiz).

Another way is cancel this patch
https://launchpad.net/ubuntu/+source/unity/7.5.0+17.04.20161130-0ubuntu1

and build a new package.I tried ,but fail.

Anyone would try to do this?

[Marco Trevisan (Treviño) (3v1n0)]

This is a tricky issue...

Probably having a setting for this is just the way to go, since the fact is that we can't scale x11 toolkits in a fractional way. While using xrandr might have performance impacts.

So, now we scale the UI at 2 and text down when 1.5 is reached. And it works better in some cases.
While I see it's not the best in others.

As workaround (works only temporary) calling
 gsettings set org.gnome.desktop.interface scaling-factor 1

So we could go back to previous revision, or maybe set a gsettings for changing this threshold.