What theme to install for Flatpak for Ubuntu Cinnamon 24.04?

Support and Help
1

Ubuntu Version:
24.04

Desktop Environment (if applicable):
Cinnamon

Problem Description:
Observing light theme in Flatpak gThumb (instead of Yaru-Cinnamon-dark) in Cinnamon.

Example:
Keep Ubuntu Cinnamon 24.04 default theme (no theme changes).

  1. Install org.gtk.Gtk3theme.Yaru-Cinnamon-dark in Flatpak.
  2. Install gThumb flatpak install flathub org.gnome.gThumb.

Observe light theme in gThumb (instead of Yaru-Cinnamon-dark).

Relevant System Information:
Radeon 660M.

Screenshots or Error Messages:

Only if run in terminal as:

/usr/bin/flatpak run --branch=stable --arch=x86_64 --command=gthumb --file-forwarding org.gnome.gThumb
Gtk-Message: 
Failed to load module "xapp-gtk3-module"

What I’ve Tried:
Installed org.gtk.Gtk3theme.Yaru-Cinnamon-dark in Flatpak.

gThumb v3.12.6 (non-Flatpak, apt version) supports Yaru-Cinnamon-dark out of the box.
I’ve read several articles on Flatpak, installing a Flatpak theme is all they basically advise.

Yaru theme packages are default:

yaru-cinnamon-theme-gtk/noble,noble,now 24.04.3 all [installed,automatic]
yaru-cinnamon-theme-icon/noble,noble,now 24.04.3 all [installed,automatic]
yaru-theme-gtk/noble,noble,now 24.04.2-0ubuntu1 all [installed,automatic]
yaru-theme-icon/noble,noble,now 24.04.2-0ubuntu1 all [installed,automatic]
yaru-theme-sound/noble,noble,now 24.04.2-0ubuntu1 all [installed,automatic]

flatpak list| grep theme
Yaru-Cinnamon-dark GTK theme    org.gtk.Gtk3theme.Yaru-Cinnamon-dark    21.10.3ubuntu5  stable  system

Thank you.

2

The latest version of that theme in Flathub is 21.10.3ubuntu5, and the last update was in Jan 2022, so it may not work in 24.04 releases. That’s just a guess on my part. I suggest you remove gthumb Flatpak, and use the .deb version of gthumb.

3

You can always copy the theme from your /usr/share/themes to your home folder hit ctrl+h to show hidden folder and create .themes folder and copy it there or download the theme and put it in that folder and then in terminal:

sudo flatpak override --filesystem=$HOME/.themes
sudo flatpak override --env=GTK_THEME=my-theme
where it says my theme erase that and put the exact name of the theme in your .themes folder you created that should fix the issue because it's going to make flatpak use that theme.
4

.deb is older than Flatpak, which is especially important e.g. for filing a bug (GNOME usually don’t accept bug reports with older versions).

5

Thanks, but with what permissions?
In $HOME?

6

it’s to give permission to flatpak to have access to folder and use the theme