Base interface for container specific state for child actors.
A child data is meant to be used when you need to keep track of information about each individual child added to a container.
In order to use it you should create your own subclass of ChildMeta and set the Container child_meta_type interface member to your subclass type, like:
static void
my_container_iface_init (ClutterContainerIface *iface)
{
// set the rest of the #ClutterContainer vtable
container_iface->child_meta_type = MY_TYPE_CHILD_META;
}This will automatically create a ChildMeta of type `MY_TYPE_CHILD_META` for every actor that is added to the container.
The child data for an actor can be retrieved using the get_child_meta function.
The properties of the data and your subclass can be manipulated with child_set and child_get which act like @set and @get.
You can provide hooks for your own storage as well as control the instantiation by overriding the Container virtual functions create_child_meta, destroy_child_meta, and get_child_meta.