06fdf2fdc8
Since 5b3fb024be, the main window is only shown when not launched with a valid UUID. As GtkDialog isn't meant to be used standalone, we currently trigger a (harmless but annoying) warning in case the main window isn't shown; we can avoid the warning by setting up the preference dialog manually instead of using the GtkDialog convenience class. https://bugzilla.gnome.org/show_bug.cgi?id=781545