QT apps have differing scaling on dual monitor setup

[Matthias]

I have a dual monitor setup with Nvidia Geforce GT1030. The card has a HDMI and a Display port output. Both displays are attached to different monitor brands with the same resolution. Gnome apps scale the same on both displays, but some QT apps like Backintime 1.2.1 or rstudio 1.2.1 have different scales on both displays.
Scaling changes when apps are moved on the desktop from one screen to the other.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu7.1
ProcVersionSignature: Ubuntu 5.0.0-32.34~18.04.2-generic 5.0.21
Uname: Linux 5.0.0-32-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair nvidia_modeset nvidia
.proc.driver.nvidia.gpus.0000.03.00.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0000:03:00.0'
.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 430.26 Tue Jun 4 17:40:52 CDT 2019
 GCC version: gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)
ApportVersion: 2.20.9-0ubuntu7.8
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Fri Nov 1 11:51:46 2019
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
DkmsStatus:
 nvidia, 430.26, 4.15.0-66-generic, x86_64: installed
 nvidia, 430.26, 5.0.0-31-generic, x86_64: installed
 nvidia, 430.26, 5.0.0-32-generic, x86_64: installed
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 NVIDIA Corporation GP108 [GeForce GT 1030] [10de:1d01] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. GP108 [GeForce GT 1030] [1043:8621]
InstallationDate: Installed on 2019-09-06 (55 days ago)
InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
MachineType: Dell Inc. OptiPlex 790
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.0.0-32-generic root=UUID=d079c1c3-6df2-4c44-89d8-a5b8462e9eeb ro quiet splash vt.handoff=1
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/30/2011
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A11
dmi.board.name: 0HY9JP
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 6
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA11:bd12/30/2011:svnDellInc.:pnOptiPlex790:pvr01:rvnDellInc.:rn0HY9JP:rvrA01:cvnDellInc.:ct6:cvr:
dmi.product.name: OptiPlex 790
dmi.product.version: 01
dmi.sys.vendor: Dell Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.97-1ubuntu1~18.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 19.0.8-0ubuntu0~18.04.3
version.libgl1-mesa-glx: libgl1-mesa-glx 19.0.8-0ubuntu0~18.04.3
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
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

[Daniel van Vugt (vanvugt)]

Sounds like Qt bug 1824753