It was referencing the wrong source, namely the main list box instead of
the treeview. Also, the callback should return TRUE, otherwise GTK tries
to load the empty invalid URI.

Fixes #1184


(cherry picked from commit 9f238c09)

So that we can use the Portal.

Fixes #3161

(cherry picked from commit 0e57c018)

Clicking on a color device row expands it and shows the buttons.
However, expanding it with the arrow does not. This is confusing. Also,
unexpanding it with the arrow again does not hide the buttons.

We can fix this by having an expanding row select itself, and an
unexpanding row unselect itself.

Fixes #11


(cherry picked from commit a1c9ba80)

Let's append ".desktop" to its app ID before launching GNOME Software.

Fixes #1022


(cherry picked from commit f1f36405)

Previously, the names of the backgrounds were read. Likely with the
accessible name computation refactor, this broke and nobody noticed.
Fix it, and properly present the selected background as well.


(cherry picked from commit bdd60e9b)