If you wonder how to properly test portals support you can use my testing application [1]. It has usage for everything, now including also test for printing portal.
[1] - https://github.com/grulja/flatpak-portal-test-kde. On středa 19. dubna 2017 14:08:52 CEST Jan Grulich wrote: > Hi, > > I would like to request/discuss inclusion of xdg-desktop-portal-kde [1] into > Plasma to have it released with Plasma 5.10 and so on. > > What is xdg-desktop-portal-kde: > It's a KDE implementation of Flatpak portals backend [2], currently with > support of AppChooser, FileChooser, Notification and Print portals. > > How it works: > An app running in sandbox communicates with outside world using > org.freedesktop.portal.Foo interfaces (each of them is one portal). These > interfaces are registered by xdg-desktop-portal (on DBus as > org.freedesktop.portal.Desktop service). This requires support in library to > make widgets etc. do calls to o.f.p.Foo interfaces instead of doing what > they usually do. This is already implemented in KNotifications and for Qt > part we have flatpak platform plugin. Then xdg-desktop-portal calls desktop > specific implementations to present native dialogs and have proper > integration. That's where xdg-desktop-portal-kde takes place. It exposes > it's implementation on DBus as org.freedesktop.impl.portal.desktop.kde > service. Then in case of KDE when user requests a file dialog from a > sandboxed application, Qt platform plugin does a dbus call to > xdg-desktop-portal instead of showing a dialog and xdg-desktop-portal > forwards this to our backend implementation and we show a native dialog to > the user, this time this dialog is not running in sandbox and user can open > a file which is outside the sandboxed application. Same way it works with > opening URLs, notifications etc. > > What do you think? > > [1] - https://cgit.kde.org/xdg-desktop-portal-kde.git/ > [2] - > http://flatpak.org/xdg-desktop-portal/portal-docs.html#idm140258860052032 > > Regards, > Jan