This is useful when accessing portal APIs when not sandboxed as it allows the portal to display info which app is making the request. For example the dialog that will be shown when QScreenCapture goes through the portal can show the app name. We need to do this as it can only be set before making any call to the portal at all which are done here for color picking or by the relevant platformthemes for settings. See the paragraph at the top of https://flatpak.github.io/xdg-desktop-portal/docs/api-reference.html and https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.host.portal.Registry.html Fixes: QTBUG-133401 Pick-to: 6.10 Change-Id: Ie55c371c6a19b3197f7798ee6233c2f19b18a6f6 Reviewed-by: David Edmundson <davidedmundson@kde.org>