GTK and Qt Applications

This guide covers theming applications built with GTK, Qt, and KDE Plasma toolkits.

GTK 3/4 Applications

GTK applications include most GNOME apps and many Linux applications. Noctalia can automatically theme them using the adw-gtk3 theme.

Setup

Install required packages:

# Arch Linux / Manjaro
paru -S adw-gtk-theme nwg-look
   
# Other distributions
# Install adw-gtk-theme and nwg-look from your package manager

Apply the GTK theme:
- Using nwg-look (recommended):
  
  GTK4 Theming In nwg-look, make sure to uncheck the GTK4 option. Leaving GTK4 checked can prevent GTK4 applications from using Noctalia’s color scheme.
  
  If you previously applied a custom GTK4 theme, you may need to hit “Clear” (found in the Preference tab) in nwg-look before reapplying and regenerating the color scheme. This ensures the new colors are accepted by GTK4 apps.
  - Open nwg-look
  - Select adw-gtk3 from the theme list
  - Click “Apply”

Using command line:

 gsettings set org.gnome.desktop.interface gtk-theme 'adw-gtk3'

Enable GTK theming in Noctalia:
- Open Settings → Color Scheme → Templates
- Toggle on GTK

Troubleshooting

Theme not applying: Completely restart GTK applications (close and reopen)

Some apps still look wrong: Some GTK apps may need GTK 4 theme separately:

gsettings set org.gnome.desktop.interface gtk-theme 'adw-gtk3'
gsettings set org.gnome.desktop.interface color-scheme 'prefer-dark'  # or 'prefer-light'

Flatpak apps: Flatpak apps may need the theme installed in their sandbox:

flatpak install org.gtk.Gtk3theme.adw-gtk3-dark
flatpak install org.gtk.Gtk3theme.adw-gtk3

Qt Applications

Qt applications include KDE apps and many cross-platform applications. Noctalia themes them through qt6ct.

Setup

Install qt6ct:

# Arch Linux / Manjaro
paru -S qt6ct
   
# Other distributions
# Install qt6ct from your package manager

Better Integration with -kde variants For better integration with KDE-specific applications, you can use the -kde variants of qtct:

qt6ct-kde: Patched version of qt6ct for better integration with KDE Qt6 applications.

qt5ct-kde: Patched version of qt5ct for better integration with KDE Qt5 applications. This may also help with theming Chromium-based browsers like Brave when they are set to use the Qt theme.

Set environment variable: Add this to your window manager configuration or shell profile:

For Niri (config.kdl):
```
environment {
  QT_QPA_PLATFORMTHEME "qt6ct"
}
```
For Hyprland (hyprland.conf):
```
env = QT_QPA_PLATFORMTHEME,qt6ct
```
For Sway (config):
```
setenv QT_QPA_PLATFORMTHEME qt6ct
```
For shell profile (~/.bashrc or ~/.zshrc):
```
export QT_QPA_PLATFORMTHEME=qt6ct
```
Enable Qt theming in Noctalia:
- Open Settings → Color Scheme → Templates
- Toggle on Qt
Configure qt6ct:
- Run qt6ct from terminal
- Go to Color Scheme tab
- Select noctalia from the dropdown
- Click Apply and OK

KDE File Picker If you use the KDE file picker, go to the Settings tab in qt6ct and set Standard dialogs to KDE (note that this needs plasma-workspace to be installed to appear as a dropdown option)..

Troubleshooting

Qt apps not themed: Ensure the environment variable is set before launching applications
qt6ct not found: Make sure qt6ct is installed and in your PATH
Theme not updating: Restart Qt applications after changing color schemes

KDE Plasma (KColorScheme)

If you’re using KDE Plasma, Noctalia can apply colors through the native KColorScheme system.

Setup

Enable KColorScheme in Noctalia:
- Open Settings → Color Scheme → Templates
- Toggle on KColorScheme
Apply in KDE System Settings:
- Open System Settings → Appearance → Colors
- Select the noctalia color scheme
- The scheme will update automatically when you change colors in Noctalia

Troubleshooting

Scheme not appearing: Restart KDE Plasma or log out and back in
Colors not updating: Ensure KColorScheme toggle is enabled in Noctalia settings