Application windows can only be added after the application has been started.
https://bugzilla.gnome.org/show_bug.cgi?id=755954
707a071 app: Warn when trying to add windows on an inert instance
gtk/gtkapplication.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
Upstream: git.gnome.org