Upstream: https://gitlab.gnome.org/GNOME/gnome-control-center/issues/17
I have a system that was upgraded from 16.04 -> 16.10 -> 17.04 -> 17.10. So now running on 17.10.
I upgraded to 17.10 because I hoped for better HiDPI scaling support.
My laptop is Dell Precision 5520 with 4k 3840x2160 15" screen, with Intel graphics (it has nvidia too, but disabled).
Additionally, I have an external Dell U3011 2560x1600 30" display connected to it.
When I logged into graphical session (selected the default Ubuntu session), I confirmed wayland is running by checking loginctl:
loginctl show-session 2 -p Type
Type=wayland
With external display connected, display settings show that the high DPI laptop screen got scaling set automatically to 200%, and the external low DPI display got scaling set to 100%. So far, looks good - automatic detection of hi dpi screens did the right thing.
The built-in Ubuntu applications like terminal, file browser or setting window work fine. When I start e.g. the terminal, it appears first on the laptop screen - it is scaled properly, then I drag it to the external screen and once I release the mouse button, the window shrinks to 2x smaller, so it adapts to lower DPI of that screen. Everything is sharp and crispy and the sizes are ok.
Problems:
* Firefox, Chrome, Chromium, Intellij IDEA all do not scale correctly on the external screen. Everything is twice too big. When started, they appear first on the built-in hiDPI screen with the correct size, but after dragging to the external screen, they remain scaled by 200%.
* When I enabled dock to be displayed on all screens, the dock icons are twice too big on the external screen. So, 200% scaling seems to be applied to the dock on both screens.
* Sometimes the mouse pointer is twice as large. Sometimes it is twice too small. I didn't figure out yet when it happens. Sometimes it is only twice too large when over the desktop background, but ok when over an application window. This is a very minor issue, but looks funny.
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What I tried so far:
Resetting dconf to factory settings with:
dconf reset -f /org/gnome/
did not help.
Then I tried enabling experimental fractional scaling, with 200% / 100% scales set (I do not really need fractional scaling, but I hoped it changes how things are rendered and where scaling is applied). This actually helped for both scaling issues - including the dock scaling problem. Windows get even properly scaled in the *middle of dragging* between displays. Everything is the right size with this setting on. Really cool.
Unfortunately now the image on the builtin display for the non-native applications like Firefox, Chrome or Idea is severely blurred. And it is blurred even if I disconnect the external display. It looks as if it rendered these apps at half the resolution (I noticed xrandr shows 1920x1080 for that screen, but ubuntu display settings window shows 3840x2160) and then upscaled twice the bitmap to reach higher 4k real screen resolution. The blur does not happen for native Ubuntu apps like terminal.
Unfortunately the blurring effect is much stronger than if I just manually force the builtin screen to 1920x1080. In this case everything is a bit lower resolution, but still sharp enough.
Therefore so far, Ubuntu 17.10 and Wayland did not improve hi dpi support for me at all, despite some rumours it should have. I still have to switch to lower resolution on the builtin display to get everything crisp and the right size.
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ApportVersion: 2.20.7-0ubuntu3.5
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
DistributionChannelDescriptor:
# This is a distribution channel descriptor
# For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
canonical-oem-somerville-xenial-amd64-20160624-2
DistroRelease: Ubuntu 17.10
InstallationDate: Installed on 2017-04-12 (234 days ago)
InstallationMedia: Ubuntu 16.04 "Xenial" - Build amd64 LIVE Binary 20160624-10:47
Package: gnome-control-center 1:3.26.2-0ubuntu0.1
PackageArchitecture: amd64
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=pl_PL.UTF-8
SHELL=/bin/bash
Tags: artful wayland-session
Uname: Linux 4.14.3-041403-generic x86_64
UpgradeStatus: Upgraded to artful on 2017-12-02 (0 days ago)
UserGroups: adm cdrom dip kvm libvirt lpadmin plugdev sambashare sudo
_MarkForUpload: True
apport information