Sets or unsets the GtkApplication associated with the window.
The application will be kept alive for at least as long as it has
any windows associated with it (see g_application_hold() for a way
to keep it alive without windows).
Normally, the connection between the application and the window will
remain until the window is destroyed, but you can explicitly remove
it by setting the @application to %NULL.
This is equivalent to calling [method@Gtk.Application.remove_window]
and/or [method@Gtk.Application.add_window] on the old/new applications
as relevant.
Sets or unsets the GtkApplication associated with the window.
The application will be kept alive for at least as long as it has any windows associated with it (see g_application_hold() for a way to keep it alive without windows).
Normally, the connection between the application and the window will remain until the window is destroyed, but you can explicitly remove it by setting the @application to %NULL.
This is equivalent to calling [method@Gtk.Application.remove_window] and/or [method@Gtk.Application.add_window] on the old/new applications as relevant.