Allow setting the layout manager type for a widget class
If we add something like:
void
gtk_widget_class_set_layout_manager_type (GtkWidgetClass *klass,
GType layout_manager);
GType
gtk_widget_class_get_layout_manager_type (GtkWidgetClass *klass);
Then we can:
- create a
GtkLayoutManager
instance automatically ingtk_widget_init()
- inspect the type of layout manager used by a
GtkWidget
subclass without instantiating it