Force dark mode for the application installed with Snap

I have a Snap configured on my system to install a specific app - Lunatask. It has it’s dark mode, but the context menu appears in light mode.

To force the application to dark mode, I’ve edited .desktop file for the app.

1. .desktop files for Snap are located in the /var/lib/snapd/desktop/applications/ directory. ls this dir to find the file you need to edit. For me it was /var/lib/snapd/desktop/applications/lunatask_lunatask.desktop. Copy this file to ~/.local/share/applications:

cp /var/lib/snapd/desktop/applications/lunatask_lunatask.desktop ~/.local/share/applications/lunatask_lunatask.desktop

2. Add GTK_THEME=Adwaita-dark to the Exec. Example:

[Desktop Entry]
X-SnapInstanceName=lunatask
Name=Lunatask
Exec=env GTK_THEME=Adwaita-dark BAMF_DESKTOP_FILE_HINT=/var/lib/snapd/desktop/applications/lunatask_lunatask.desktop /var/lib/snapd/snap/bin/lunatask %U
Terminal=false
Type=Application
Icon=/var/lib/snapd/snap/lunatask/51/meta/gui/icon.png
StartupWMClass=Lunatask
Comment=Encrypted to-do list, habit and mood tracker, journaling and notes app
Categories=Office;

3. Open/restart the application.

References

• https://askubuntu.com/a/1177094
• https://askubuntu.com/a/117342