main-window: use g_app_info_launch() instead of gdk_spawn_on_screen() (#637854)
main-window: use g_app_info_launch() instead of gdk_spawn_on_screen() (#637854)

GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets