Retrieves the type of the [class@Gtk.LayoutManager] used by widgets of class @widget_class.
See also: [method@Gtk.WidgetClass.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 widgets of class @widget_class.
See also: [method@Gtk.WidgetClass.set_layout_manager_type].