GIMP icon sizes small on large and huge setting

[Anonymous Anonymous]

Description:
Increasing the icon size setting increases the size on some UI elements, while decreasing the size of others. Sizes appear to increase up to a point, but once that point is reached, the size reverts to small. This occurs at large for most elements, but some get larger and revert at huge instead.

Reproduce:
$ gimp
click: Edit -> Preferences -> Icon theme (under Interface section) -> Custom icon size (drop-down menu)
then the toolbar icons of "Large" and "Huge" settings on the icon size slider are smaller than "Medium", being the same size as "Small" instead.

Where I've reproduced it:
Short: gimp 2.10.6 and 2.10.8 on Ubuntu 18.10 and Ubuntu 19.
Long: I've reproduced it in an Ubuntu 18.10 fresh install and a qemu-kvm virtual machine. I've reproduced the problem in gimp 2.10.8 (apt) on Ubuntu 19 (development branch), so it doesn't look like it is fixed in newer versions.

Where I couldn't reproduce it:
When I tried to replicate it on Ubuntu 19 (development branch) with the flatpak from the gimp website, the bug did not occur. Same for 18.10. Gimp version must also be new enough to have icon size setting.

NOTE:
I've reported it on https://gitlab.gnome.org/GNOME/gimp/issues/2313 but thought that this bug would benefit from the attention of the Ubuntu Community/Canonical, given that the bug was reproduced on Ubuntu, but not on Debian, where gimp is an earlier version, or using flatpak. The problem may be with the apt installation, since flatpak works, and which the GIMP team might not be able to fix as easily as Ubuntu.

$ lsb_release -rd
Description: Ubuntu 18.10
Release: 18.10

$ apt-cache policy gimp
gimp:
  Installed: 2.10.6-3
  Candidate: 2.10.6-3
  Version table:
 *** 2.10.6-3 500
        500 http://us.archive.ubuntu.com/ubuntu cosmic/universe amd64 Packages
        100 /var/lib/dpkg/status

What I expected to happen:
Icon size increases as slider increases through small, medium, large, and huge

What happened instead:
Icon sizes revert to small at large setting, other elements change in unexpected ways at huge setting.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: gimp 2.10.6-3
ProcVersionSignature: Ubuntu 4.18.0-15.16-generic 4.18.20
Uname: Linux 4.18.0-15-generic x86_64
ApportVersion: 2.20.10-0ubuntu13.2
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Fri Feb 22 19:48:01 2019
ExecutablePath: /usr/bin/gimp-2.10
InstallationDate: Installed on 2019-02-11 (11 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
 TERM=screen-256color
 XDG_RUNTIME_DIR=<set>
 PATH=(custom, no user)
SourcePackage: gimp
UpgradeStatus: No upgrade log present (probably fresh install)

[Anonymous Anonymous (6cb0036a99998a7eb6fc812ca9b70ea1)]

I believe these settings are stored at '~/.config/GIMP/2.10/gimprc', although bug occurs before setting is saved when "OK" is pressed in Preferences.

[Launchpad Janitor (janitor)]

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

[Andrew Kornilov (akornilov)]

I can confirm that issue on the latest development version of Ubuntu 20, on HiDPI 15" display (3840x2160)
flatpak version looks less or more correct (still not very usable) and icon size setting works.
repository version has tiny icons and icon size settings does not work.

[Philippe Alff (almghandi)]

I have the same issue on a freshly installed Ubuntu 20.04, using the apt package of gimp.
The laptop is a X270 12" with 1920x1080.
I noticed that the problem only occurs at fractional scaling (125%, 150%), at 100% scaling the icon sizes behave normal.

[Robert Oswald (robert-oswald)]

I have the same issue on Ubuntu 20.04 on a Macbook 13" Retina and a PC with 4K 27" Monitor, both scaling at 200%.
Im using an AppImage of Gimp 2.10.*, actual 2.10.20.

[Kevin Barry (barryk)]

I was able to work around the issue by changing the theme in Gnome Tweaks from Yaru to Adwaita or sticking with Yaru and removing the gtk-icon-sizes defintion (note it spans multiple lines) in the gtk2 rc at /usr/share/themes/Yaru/gtk-2.0/gtkrc

This may break the look of other gtk2 applications

--- /usr/share/themes/Yaru/gtk-2.0/gtkrc.orig 2020-09-09 16:46:30.332864005 -0500
+++ /usr/share/themes/Yaru/gtk-2.0/gtkrc 2020-09-09 16:47:25.297208691 -0500
@@ -34,12 +34,7 @@
 # Set GTK settings
 gtk-auto-mnemonics = 1
 gtk-primary-button-warps-slider = 1
-gtk-icon-sizes="gtk-menu=16,16:
-gtk-button=16,16:
-gtk-small-toolbar=16,16:

-gtk-dnd=16,16:
-gtk-dialog=16,16"
 gtk-toolbar-style = GTK_TOOLBAR_ICONS
 gtk-menu-images = 0
 gtk-menu-popup-delay = 0

[Petter Sundlöf (petter-sundlof)]

This is still happening on GIMP 2.10.18 on Ubuntu 20.04, and renders GIMP pretty unusable on a 4K display

[Sarmad Siddiqui (iuqiddis)]

I just wanted to add a temporary workaround for those who stumbled upon this bug report, building off Kevin Barry(barryk)'s post and Archwiki's Gimp 2.10 section from the HiDPI article (https://wiki.archlinux.org/index.php/HiDPI#Gimp_2.10)

I'm using a 15.6" 4k screen, so you should adjust your values to best work for your case.

I followed these steps from archwiki:

"To fix toolbar icon sizes, update Preferences->Interface->Icon Theme->Custom icon size to huge or other value (This is the bug here--this bit doesn't work as intended. For now move the scale up to huge and get to the next section)

If menu fonts are still too small you can update an existing theme by copying it from /usr/share/gimp/2.0/themes into ~/.config/GIMP/2.10/themes/ and changing gtk-font-name and font_name in gtkrc into something bigger like Sans 16. Then select the new theme from Preferences > Interface > Theme. When copying make sure to rename the new directory into something different from the original name (example Dark > DarkHighDPI)"

Once you've made the theme copy, paste the edits that Kevin Barry has proposed into the ~/.config/GIMP/2.10/themes/DarkHighDPI/gtkrc text file in the # Set GTK settings section, but with the following values:

gtk-icon-sizes="gtk-menu=48,48:
gtk-button=48,48:
gtk-small-toolbar=48,48:

gtk-dnd=48,48:
gtk-dialog=48,48"

In my case of a 4k 15.6" screen, changing the font size to 16 and the various gtk sizes to 48,48 worked to make the huge setting the biggest. If you have a different ppi, try playing with multiples of 16 and see if you get a setting that works for you. The benefit of this approach over Kevin Barry's above approach is that no other application is affected