Issue with Arc-Lighter and Firefox

[tupo2]

• Distribution and version: Ubuntu 22.04
• Versions for the affected applications/desktops/toolkits: GTK 3.24.33
• Installation method (package or compiled manually): Package
• Arc-theme version: 20220405

I encounter an issue with Arc-Lighter and Firefox, the windows decorations are incorrect:

On the other hand, no problem with Arc, Arc-Dark and Arc-Darker:

[jnsh]

I can't reproduce this on my system, and didn't immediately see anything wrong with the Ubuntu package.

-Does every other application work without issues using Arc-Lighter? -Are there any warnings/errors when using Arc-Lighter, if you start firefox from command line, that aren't there when using the other variants?

[tupo2]

-Does every other application work without issues using Arc-Lighter?

No, Ubuntu Software has the same issue, which comes from a Snap package like Firefox (but with the other variants, no problem).

-Are there any warnings/errors when using Arc-Lighter, if you start firefox from command line, that aren't there when using the other variants?

This displays: Failed to load module "canberra-gtk-module". Same for other variants. I did: sudo apt install libcanberra-gtk-module libcanberra-gtk3-module but it didn't help.

[tupo2]

I found 2 workaround:

Unclear why changing directory name of the theme works:

sudo mv /usr/share/themes/Arc /usr/share/themes/Arc-Light
sudo mv /usr/share/themes/Arc-Lighter /usr/share/themes/Arc
or
sudo mv /usr/share/themes/Arc-Lighter /usr/share/themes/Arc-Dark
or
sudo mv /usr/share/themes/Arc-Lighter /usr/share/themes/Arc-Darker

2nd workaround:

sudo snap remove firefox
sudo add-apt-repository ppa:mozillateam/ppa
sudo apt install firefox=102.0.1+build1-0ubuntu0.22.04.1~mt1

[jnsh]

So the problem exists only with snap packages. I'm not too familiar with snap, but at least with flatpak, you need Arc-theme installed as flatpak package to work with flatpak applications. Maybe there's an Arc-theme snap package on your system, that the snap applications are using, and is missing the lighter variant?

Since this is a problem with snap packages, that I don't have anything to do with, I doubt that I can help much further. I'd suggest seeking for help from ubuntu/snap support channels. However please report back if you find a solution, since others may be looking for a fix for this here.