When using gtk.application.Application, it is not necessary to call funcGtk.init
manually. It is called as soon as the application gets registered as
the primary instance.
Concretely, funcGtk.init is called in the default handler for the
GApplication::startup signal. Therefore, gtk.application.Application subclasses should
always chain up in their GApplication::startup handler before using any GTK
API.
Note that commandline arguments are not passed to funcGtk.init.
If application_id is not null, then it must be valid. See
[gio.application.Application.idIsValid].
If no application ID is given then some features (most notably application
uniqueness) will be disabled.
Creates a new gtk.application.Application instance.
When using gtk.application.Application, it is not necessary to call funcGtk.init manually. It is called as soon as the application gets registered as the primary instance.
Concretely, funcGtk.init is called in the default handler for the GApplication::startup signal. Therefore, gtk.application.Application subclasses should always chain up in their GApplication::startup handler before using any GTK API.
Note that commandline arguments are not passed to funcGtk.init.
If application_id is not null, then it must be valid. See [gio.application.Application.idIsValid].
If no application ID is given then some features (most notably application uniqueness) will be disabled.