Display Scaling / Border issues

Hello All,

I'm having wierd display application scaling issues. I'm running KDE Plasma. The issue only happens when using the internal and external display on the laptop, the external display is connected over HDMI. If I only use the internal laptop display I have no issues.

Scaling is turned up globally to 1.6.

Example 1: When trying to take a screenshot with spectacle, the screen "shifts" upward:

Example 2: Virtualbox displays of manager / VMs don't resize correctly:


Any and all pointers would be greatly appreciated.

inxi -Fxxx:

System:
  Host: xxxx Kernel: 5.4.0-2-MANJARO x86_64 bits: 64 
  compiler: gcc v: 9.2.0 Desktop: KDE Plasma 5.17.2 
  tk: Qt 5.13.1 wm: kwin_x11 dm: SDDM Distro: Manjaro Linux 
Machine:
  Type: Laptop System: LENOVO product: 20QNCTO1WW 
  v: ThinkPad P53 serial: <root required> Chassis: type: 10 
  serial: <root required> 
  Mobo: LENOVO model: 20QNCTO1WW v: SDK0R32862 WIN 
  serial: <root required> UEFI: LENOVO v: N2NET30W (1.15 ) 
  date: 09/26/2019 
Battery:
  ID-1: BAT0 charge: 92.7 Wh condition: 96.6/90.0 Wh (107%) 
  volts: 12.7/11.2 model: SMP 02DL028 type: Li-poly 
  serial:   774 status: Unknown cycles: 6 
CPU:
  Topology: 6-Core model: Intel Core i7-9850H bits: 64 
  type: MT MCP arch: Kaby Lake rev: D L2 cache: 12.0 MiB 
  flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 
  vmx 
  bogomips: 62431 
  Speed: 1185 MHz min/max: 800/4600 MHz Core speeds (MHz): 
  1: 1185 2: 910 3: 962 4: 873 5: 1065 6: 1054 7: 861 8: 1192 
  9: 1750 10: 1128 11: 2707 12: 1753 
Graphics:
  Device-1: Intel UHD Graphics 630 vendor: Lenovo 
  driver: i915 v: kernel bus ID: 00:02.0 chip ID: 8086:3e9b 
  Device-2: NVIDIA TU117GLM [Quadro T2000 Mobile / Max-Q] 
  vendor: Lenovo driver: nvidia v: 440.26 bus ID: 01:00.0 
  chip ID: 10de:1fb8 
  Display: x11 server: X.Org 1.20.5 
  driver: modesetting,nvidia compositor: kwin_x11 
  resolution: 2560x1440~60Hz 
  OpenGL: renderer: Quadro T2000/PCIe/SSE2 
  v: 4.6.0 NVIDIA 440.26 direct render: Yes 
Audio:
  Device-1: Intel Cannon Lake PCH cAVS vendor: Lenovo 
  driver: snd_hda_intel v: kernel bus ID: 00:1f.3 
  chip ID: 8086:a348 
  Device-2: NVIDIA vendor: Lenovo driver: snd_hda_intel 
  v: kernel bus ID: 01:00.1 chip ID: 10de:10fa 
  Sound Server: ALSA v: k5.4.0-2-MANJARO 
Network:
  Device-1: Intel Ethernet I219-LM vendor: Lenovo 
  driver: e1000e v: 3.2.6-k port: efa0 bus ID: 00:1f.6 
  chip ID: 8086:15bb 
  IF: enp0s31f6 state: down mac: 98:fa:9b:cc:cb:fc 
  Device-2: Intel Wi-Fi 6 AX200 driver: iwlwifi v: kernel 
  port: 2000 bus ID: 52:00.0 chip ID: 8086:2723 
  IF: wlp82s0 state: up mac: 04:ed:33:11:7a:b0 
  IF-ID-1: vboxnet0 state: up speed: 10 Mbps duplex: full 
  mac: 0a:00:27:00:00:00 
  IF-ID-2: virbr0 state: down mac: 4a:88:31:f0:ed:64 
  IF-ID-3: virbr0-nic state: down mac: 52:54:00:6b:58:11 
Drives:
  Local Storage: total: 953.87 GiB used: 281.83 GiB (29.5%) 
  ID-1: /dev/nvme0n1 vendor: Samsung 
  model: MZVLB1T0HBLR-000L7 size: 953.87 GiB speed: 31.6 Gb/s 
  lanes: 4 serial: S4EMNF0M909221 rev: 4M2QEXF7 scheme: GPT 
  ID-2: /dev/nvme1n1 vendor: Samsung 
  model: MZVLB1T0HBLR-000L7 size: 953.87 GiB speed: 31.6 Gb/s 
  lanes: 4 serial: S4EMNF0M909225 rev: 4M2QEXF7 scheme: GPT 
Partition:
  ID-1: / size: 903.99 GiB used: 281.83 GiB (31.2%) fs: ext4 
  dev: /dev/nvme0n1p2 
  ID-2: swap-1 size: 34.15 GiB used: 0 KiB (0.0%) fs: swap 
  dev: /dev/nvme0n1p3 
Sensors:
  System Temperatures: cpu: 60.0 C mobo: 41.0 C gpu: nvidia 
  temp: 41 C 
  Fan Speeds (RPM): cpu: 1957 
Info:
  Processes: 289 Uptime: 20m Memory: 30.98 GiB 
  used: 2.48 GiB (8.0%) Init: systemd v: 242 Compilers: 
  gcc: 9.2.0 Shell: bash v: 5.0.11 running in: konsole 
  inxi: 3.0.36

Welcome to Manjaro!

I regret to inform you that double posting is not adding more on your issue.

Nevertheless, on your issue, there are currently several bugs on Plasma monitors (like this), so you might have to wait for Plasma developers to do something.
About VirtualBox, maybe review your GPU settings and alter the used driver.

With Plasma scaling, AFAIK it uses monitor names in this setting. I suggest you clear Plasma cache, to make sure your setup is clean and try again.

For scaling it is best to keep things in increments of ~.25 .. so maybe 1.5 is good for your case ?
But I should mention that plasma scaling (and especially 'fractional scaling') isnt exactly perfect. I find setting a number of options manually to provide a better experience. If you want to try - I wrote a script for it.

Thanks for your replies!
I'll check out your script and will also test without scaling and a second monitor, just to confirm that the scaling is in fact the problem.
Yesterday I also noticed that VLC won't display any video and also shows similar scaling artifacts when resizing the UI. Maybe this is a hint, do VLC and Virtualbox use the same UI-Technology to display perhaps?

For your exact issue using plasma and fractional scaling - I have no idea - but VirtualBox - to my experience - works best when you set the display adapter to VBoxSVGA - preferably before installing the guest OS.

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