Default background schema override is ignored

[Rudra Saraswat]

This package ships a schema override to set the default background for Ubuntu Unity users. gnome-shell and unity (unity-settings-daemon to be precise) share the same schema and key for the background, picture-uri under org.gnome.desktop.background). The schema override (with a priority of 30) thus overrides the value of that key set by ubuntu-settings to set Ubuntu Unity's wallpaper as the default, and there haven't been any issues with this in the past. However, in this release, the schema seems to be ignored/overridden, something that's rather unexpected as it has the highest priority (above ubuntu-settings, which also sets the picture-uri key and has a priority of 10).

This bug can be reproduced by downloading the daily ISO of Ubuntu Unity from 1st or 2nd April.

`gsettings get org.gnome.desktop.background picture-uri` and `gsettings get org.gnome.desktop.background picture-uri-dark` return 'warty-final-ubuntu.png' despite the override, so setting 'picture-uri-dark' (as suggested by jbicha) didn't make any difference (u-s-d doesn't use the key iirc). jbicha also suggested moving the override file to 'debian/gsettings-override' and using `dh_installgsettings --priority 30` (something I wasn't aware of earlier, since this package has traditionally depended on the glib-2.0 package hook) to install the override, but that didn't help either.

TLDR the gschema override shipped by this package seems to somehow be overridden or ignored (still not certain), resulting in Ubuntu Unity using the default wallpaper from Ubuntu, and this could be a potential release blocker.

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Ubuntu Unity "Lunar" daily ISOs from 1st and 2nd April in VirtualBox VMs, up-to-date packages, in live session (2nd April ISO) as well as installation (1st April ISO).

[Jeremy Bícha (jbicha)]

Set the top line of your gsettings override file to
[org.gnome.desktop.background:Unity]

You may need to use that :Unity suffix for any other overrides you have.

Background
----------
$XDG_CURRENT_DESKTOP on Ubuntu Unity is Unity:Unity7:ubuntu
On Ubuntu Desktop, it is ubuntu:GNOME

ubuntu-settings installs an override with
[org.gnome.desktop.background:ubuntu]
That matches one of the values in Ubuntu Unity's $XDG_CURRENT_DESKTOP and is more specific than just org.gnome.desktop.background

Other Suggestions
-----------------
1. As we discussed earlier, I recommend setting both picture-uri and picture-uri-dark
2. If you name your override file debian/gsettings-override, then dh_installgsettings will install it and run the required glib-compile-schemas step for you.\
https://manpages.debian.org/unstable/dh_installgsettings
3. To use the priority level 30, just override dh_installgsettings with dh_installgsettings --priority 30
4. Please drop ${shlibs:Depends} . That is used for shared C libraries which this package does not have.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ubuntu-unity-backgrounds - 23.04.1-0ubuntu1

---------------
ubuntu-unity-backgrounds (23.04.1-0ubuntu1) lunar; urgency=high

  * 30_background.gschema.override: set org.gnome.desktop.background for Unity
    (LP: #2015118)

 -- Rudra Saraswat <email address hidden> Thu, 13 Apr 2023 20:30:50 +0530