Setting qt icon theme to "Papirus-Maia" causes apps to use Adwaita icons

[ParadaCarleton]

Describe the bug
Setting the qt icon theme to "Papirus-Maia" causes apps to use Adwaita icons.

To Reproduce
Steps to reproduce the behavior:

1. Go to qt6conf
2. Click on "Icon Theme"
3. Switch to "Papirus-Maia"

Expected behavior
Theme should use Papirus icons. (Unsure what makes Papirus-Maia different from Papirus; the name made me assume it would just incorporate the Maia accent color, but apparently not?)

Environment:

• Desktop Environment: GNOME
• Kernel Version: 6.12.63-1-MANJARO
• Manjaro Version: 25.10 Zetar
• Graphics Driver: NVIDIA
• Device: Laptop

Additional context
Add any other context about the problem here (e.g., logs).

[yochananmarqos]

Have you verified the icon theme is actually being set?

cat ~/.config/qt6ct/qt6ct.conf | grep icon_theme

What apps have you noticed are affected?

[ParadaCarleton]

Have you verified the icon theme is actually being set?

Looks like it is:

❱ cat ~/.config/qt6ct/qt6ct.conf | grep icon_theme
icon_theme=Papirus-Maia

This seems to affect all apps—setting the icon theme to "Papirus-Maia" and then restarting Qt6ct is enough to make the window decorations switch back to LibAdwaita. (Is a separate Papirus-Maia theme actually necessary? I can't work out what makes it different from the regular Papirus theme, other than the broken window controls.)

[yochananmarqos]

Any setting in the Qt6 Configuration Tool (aka Qt6 Settings) does not affect "all apps"--only Qt 6 applications.

Either way, setting the icon theme does not change window decorations. Do you have the Style set to kvantum under Appearance? What theme do you have set in Kvantum Manager?

The Papirus Maia icon theme colors the folder icons, otherwise all the application icons are the same as Papirus.

[ParadaCarleton]

Any setting in the Qt6 Configuration Tool (aka Qt6 Settings) does not affect "all apps"--only Qt 6 applications.

All Qt6 apps, I meant.

Either way, setting the icon theme does not change window decorations.

Definitely does for me.

Do you have the Style set to kvantum under Appearance? What theme do you have set in Kvantum Manager?

Yes; Libadwaita-Maia.

The Papirus Maia icon theme colors the folder icons, otherwise all the application icons are the same as Papirus.

Hmm, would that have any effect on GNOME? I'm guessing not.

[yochananmarqos]

Something else is going on here. Qt6 itself (via qt6-base) is what controls the window decorations no matter what Kvantum theme one is using.

would that have any effect on GNOME?

Yes, it colors the folder icons in Nautilus (aka Files).

What icon theme are you using globally? Papirus-Maia?

gsettings get org.gnome.desktop.interface icon-theme

[ParadaCarleton]

What icon theme are you using globally? Papirus-Maia?

Yes.

Yes, it colors the folder icons in Nautilus (aka Files).

But Nautilus doesn't use Qt6, as far as I know, so setting this in Qt6 shouldn't have any effect. Maybe if a Qt app opens a filepicker?

Something else is going on here. Qt6 itself (via qt6-base) is what controls the window decorations no matter what Kvantum theme one is using.

Right; I'm describing the Qt6 icon theme (which is set in qt6ct, under "icon theme"), not any Kvantum theme.