KCMs can be individually disabled by KIOSK if desired but wallpaper configuration cannot (unless you lock down Plasma completely). Hence, at least honoring the ghns restriction here, until we have a proper solution (that is a QtQuick equivalent of KNS3::Button).
Also, KNS3::DownloadDialog refuses to open when ghns is restricted *but* this applies only to using open() or exec() but not a blatant show() we do from QML.

Placed the following in kdeglobals

[KDE Action Restrictions]
ghns=false

Button did no longer show up.