We explicitly include NoDisplay applications in the ShellAppSystem because
we want app tracking for them, but we explicitly filter NoDisplay applications
out when showing them to the user because we don't want to show them to the
user. We also based our "All" apps view on a flattened list of apps. While
we did check for NoDisplay on the app item itself, we didn't check against
its parents. Refactor the app display view to not use a separate flat list
of applications, but instead a concatenation of all the applications in all
the loaded categories.
https://bugzilla.gnome.org/show_bug.cgi?id=658176
196f6c241a