Retrieves the type of the [class@Gtk.LayoutManager] used by the GtkWidget class.
See also: gtk_widget_class_set_layout_manager_type()
type of a GtkLayoutManager subclass, or %G_TYPE_INVALID
See Implementation
Retrieves the type of the [class@Gtk.LayoutManager] used by the GtkWidget class.
See also: gtk_widget_class_set_layout_manager_type()