GtkContainerClasshandle_border_width

Modifies a subclass of GtkContainerClass to automatically add and remove the border-width setting on GtkContainer. This allows the subclass to ignore the border width in its size request and allocate methods. The intent is for a subclass to invoke this in its class_init function.

gtk_container_class_handle_border_width() is necessary because it would break API too badly to make this behavior the default. So subclasses must “opt in” to the parent class handling border_width for them.