Binary package “xdg-desktop-portal-gtk” in ubuntu xenial

GTK+/GNOME portal backend for xdg-desktop-portal

 xdg-desktop-portal-gtk provides a GTK+/GNOME implementation for the
 desktop-agnostic xdg-desktop-portal service. This allows sandboxed
 applications to request services from outside the sandbox using
 GTK+ GUIs (app chooser, file chooser, print dialog) or using GNOME
 services (session manager, screenshot provider).

Published versions