Sets the type to be used for creating layout managers for widgets of @widget_class.
The given @type must be a subtype of [class@Gtk.LayoutManager].
This function should only be called from class init functions of widgets.
The object type that implements the GtkLayoutManager for @widget_class
See Implementation
Sets the type to be used for creating layout managers for widgets of @widget_class.
The given @type must be a subtype of [class@Gtk.LayoutManager].
This function should only be called from class init functions of widgets.